Tuesday Night Technical Discussion

Synopsis:

Low pressure will make it's was off the coast leaving a westerly flow for the region in it's wake for Tuesday night through Thursday, bringing cold temperatures. High pressure will move over the Mid Atlantic Region Friday and bring a southerly component to the wind and allow for some slight warm advection. Another system will affect the region Saturday morning through the rest of the weekend bringing a chance for mixed precipitation across the state.

Short Term: (Tuesday night through Thursday night)

A mean westerly flow Tuesday night through Thursday will produce frigid temperatures. The highest temperatures will only reach the mid to upper 20's for the entire state both Wednesday and Thursday and low temperatures could reach single digits Thursday night for higher elevations in western portions of the state indicated by the 18Z 12km NAM. The potential for lake effect snow Tuesday night and Thursday night will be limited to the extreme northern and northwestern portions of the state or even north of the state due to a mean westerly wind with a southerly component at times. Some lake effect snow showers are possible for northwestern counties Wednesday night due to a slight northerly component to the mean westerly flow.

Long Term: (Friday into the weekend)

High pressure passing to the south of the state will introduce a south westerly wind to the region and help advect some warmer temperatures into the state. The southern half of the state could reach high temperatures in the low 30's on Friday as indicated by the 18Z 12km NAM. A system will approach the region from the southwest and begin to impact the state Saturday morning with light snow showers but a changeover to mixed precipitation is possible as warm flow off the ocean is pushed inland. The system looks to have two centers of low pressure, thus a Miller Type B storm, and the coastal low will be most dominant indicated by the 18Z GFS. This will keep most of the heavy precipitation to the south and east of PA. The system will move off the coast Sunday and leave behind cold advection, and a north to northwesterly flow providing a chance for lake effect snow showers Sunday night for northwestern counties.

~ A.J. Herbert

Technical Discussion for Wednesday Night Shift (12/4)

Synopsis:

A tricky winter weather pattern will be set up across Pennsylvania for the next several days. A warm front will bring unseasonably mild temperatures to the state Thursday, while a cold front entering Thursday afternoon will start a two-day period of precipitation, as the front will hang across the state. Saturday is a dry, partly sunny day, while Sunday and Monday we could see another shot at a mixed bag of precipitation across much of the Commonwealth.

Short Term: through Friday morning

As of 0300z, the WPC surface analysis placed the warm front associated with a deepening low in the upper Midwest was just starting to cross into southwestern PA. It will continue to move northeast throughout the night, thus overnight low temperatures are expected as the front crosses. After the frontal passage, mild air will push in quickly (Wheeling, WV is at 57 degrees directly behind the front).

This means that temperatures will warm up significantly on Thursday, despite lingering clouds once again. Most locations will make it at least to the upper 50s, with some locations in southern PA pressing towards the mid-60s for a high, more than 20 degrees above normal. The cold front should sweep into western PA by mid-afternoon, as indicated by a general model consensus. Light precipitation falls ahead of the front, but the bulk will follow behind the front, according to model guidance. As the front gets hung up across the state, rain will persist overnight Thursday night into Friday morning.

Long Term: Friday – Monday

A shot of arctic air will come in during the day on Friday, cooling temperatures aloft first. While some locations could see a brief amount of mixed precipitation, most soundings for late Friday afternoon show a quick changeover to all snow. Most of the snow showers we see across the state Friday night will be the result of shortwave disturbances along the deep trough set up across the US, and their strength and track are not exactly certain yet, thus accumulation amounts vary widely across the different models, including among SREF members. It does seem likely that much of the state will wake up with at least a coating of new snow Saturday morning.

The stalled front will finally move away early Saturday, leading to much of the state seeing the first significant sunlight all week. The cold air will remain in place, however, so temperatures will stay at or below seasonal normals and will dip quite low overnight. For Sunday models indicate warmer air beginning to overrun into Pennsylvania by the afternoon hours. As the atmosphere moistens, there becomes great concern for significant ice accretion in parts of the state Sunday night into Monday. Soundings from the 0z GFS show the greatest likelihood for sleet changing to freezing rain around midnight on Monday. As temperatures continue to warm, the precipitation changes over to all rain Monday morning before ending Monday afternoon. Although the exact temperature profile (and therefore precipitation type) is not nailed down yet, the forecast beyond Monday's storm becomes a bit less active and much colder.

-Devin Boyer

Synopsis: 

A warm front will lift north into Pennsylvania today, bringing along above average temperatures throughout the state.  A cold front from the west will move through Pennsylvania late Thursday afternoon into late Thursday night, before it becomes nearly stationary in the Mid-Atlantic region Friday.  Waves will accompany the stationary front, which is set to bring mix precipitation into the central regions of the state, and light snow accumulations for the western regions of the Commonwealth Friday afternoon into Friday evening.

Short Term:  (Wednesday night through Thursday night)

The fog and the low clouds in the central region have scoured out in the warm sector.  The warm sector has made its way into the area, bringing temperatures 5-10 degrees above normal.  Drizzle and fog will appear tonight due to warm air advection from the south ahead of the cold front.  High temperatures tomorrow could range from 10-20 degrees above normal.  The cold front will arrive into Western Pennsylvania around 18z tomorrow.  Scattered rain showers will arrive ahead of the cold front tomorrow afternoon.

Long Term:  (Friday into the weekend)

An arctic cold front will push eastward toward Pennsylvania Friday night, and bringing artic cold air for Saturday.  This would be the first out of the two mixed precipitation events.  A mild southwest air flow will support rain for most of area Friday, with a changeover to frozen precipitation   from Northwest Pennsylvania to Southeastern Pennsylvania Friday night.  As the frontal boundary moves eastward, colder air will overtake the warm air.  As shortwaves ride northward along the front Friday, air columns will be cold enough to support all snow, which could create accumulations of 3 – 5 inches Friday night.  Another mixed wintry precipitation event will occur on Sunday afternoon.  Medium range models and ensemble guidances depicts a low pressure developoing in the Tennessee valley, and lifting northward during late Saturday into Sunday.  On Sunday, deep moisture and warm air advection aloft over a sub-freezing surface temperature will support frozen precipitation for the area.  GFS and ECMWF guidance shows that freezing rain accumulations could occur early Sunday afternoon into Sunday evening for the central regions of Pennsylvania.  As the models update overtime, the confidence level of the storms track & precipitation type will increase.

~ Chad

Tuesday Night Technical Discussion

Synopsis:

High pressure will move off the coast as a low-pressure system to our west will move north of the region. The state will be in the warm sector of the system and temperatures will be warm for the middle of the week. The low-pressure's associated cold front will stall across the state Thursday and Friday, as well as into the weekend, bringing widespread precipitation. A second system will swiftly make its way from the gulf and provide a chance for mixed precipitation for the end of the weekend and for the beginning of next week.

Short Term: (Tuesday night through Wednesday night)

Tuesday night there will be a slight chance for some light freezing rain or drizzle for extreme northern PA, otherwise cloudy conditions will persist overnight and low temperatures will remain in the 30's for the majority of the state as indicated by the 18Z 12km NAM. As the low pressure and it's associated cold front to our west slowly approaches the region, temperatures will begin to warm for Wednesday, as we will be located in the warm sector with a southeasterly flow. This southeasterly flow could provide enough moisture to produce a few scattered rain showers for higher elevations located in the eastern counties as the moist air ascends the mountains.

Long Term: (Thursday into the weekend)

Temperatures will continue to warm Thursday with high temperatures ranging from the low to mid 50's for northern counties to low 60's for southern PA indicated by the 18Z 12km NAM. The 18Z NAM, as well as the 18Z HI-RES 4km NAM and the 21Z SREF Mean, have the frontal precipitation reaching southeastern portions of the state by 18Z Thursday, but the 18Z GFS is a bit slower with the precipitation not reaching southern counties until 03Z Friday. Pieces of energy will make their way from the southwest and move northeasterly along the stalled cold front across the state beginning Thursday night. This will create bands of precipitation to be oriented from the southwest to the northeast from Thursday night into the weekend, as pieces of energy continue to move northeast along the cold front and bring widespread rain showers across the state. As the stalled cold front finally makes its way off the coast, cold air will move into the state and provide a chance for some snow showers in northwestern counties Friday night as the precipitation exits the state to the southeast. A quick moving system from the gulf will move just west of the state and bring a chance for some mixed precipitation Sunday night through Monday. 

 ~ A.J. Herbert

Tuesday Night Technical Discussion

Synopsis:

High pressure will continue to make its way east and sit over New England until Thursday night. A cold front will traverse the state Friday and produce scattered rain showers across the region. Artic air will move into the region behind this system, along with scattered lake effect snow showers, especially for northwestern portions of the state, during the weekend.

Short Term: (Tuesday night through Thursday night)

High pressure will dominate the weather pattern for the northeastern states Tuesday night through Thursday night. Low temperatures for Tuesday night will be in the low to mid 20's statewide, indicated by the 18Z 12km NAM. As the flow become more southerly and skies remain mostly clear, high temperatures will moderate, with the entire state at least reaching the low 40's and southwestern PA reaching low 50's by Thursday. Clouds will begin to move in Thursday afternoon and, along with a southerly flow, will keep low temperatures for Thursday from dropping.

Long Term: (Friday into the weekend)

A mean southerly flow will allow temperatures to rise Friday just ahead of the cold front. The 12z GFS has the pre frontal precipitation reaching northwestern PA by 18Z Friday, but the 12Z NAM is a bit quicker and has the precipitation reaching the state by 12Z on Friday. GFS is currently slow and the NAM is doing much better with the timing. Expect some precipitation in the northwestern counties on Friday between 10Z and 12Z. The low pressure associated with the frontal passage will move north over Canada and sit for the weekend. A northerly flow behind the front will allow for cold air advection, which will usher in a cold air mass for the weekend. The flow will shift northwesterly and lake effect snow showers are possible for the northern and western portions of PA for Saturday night through Monday. High pressure will begin to make its way towards the state for the beginning of the workweek and the northwesterly flow will subside, cutting off the lake effect activity.

~ A.J. Herbert

Tuesday Afternoon Discussion

Synopsis:

The remainder of the week looks to be standard fall weather across Pennsylvania. Mostly cloudy skies and cool temperatures are what you can expect for Wednesday and Thursday. Highs in the 40's and lows in the upper 20's should be the norm across the state. Things change on Friday when we warm up a bit ahead of an approaching front. Temperatures should get back into the 50's for at least some the area on Friday. A blast of arctic air will slam into the region on Saturday bringing the coldest temperatures of the fall so far and a few snow showers are likely as the front pushes through.

Outlook:

An area of steady, high pressure and associated subsidence will dominate PA weather today and tomorrow.  Northerly winds and mostly clear skies will lead to below-normal temps and large diurnal temp swings.  Our next system develops in the wake of the high and closes off ~18Z Friday afternoon over the Great Lakes.  Yesterday, the ECMWF had this storm moving up the east coast with Nor'easter potential, but the current solution brings it up into Canada to our NW.  Consequently, instead of feeling the direct effects of the low, we will experience an Arctic cold front Saturday morning.  The precipitation might clear out by gametime, but so will the warm air.  With the 510 line in southern PA, we will likely experience the coldest air of the season so far, with highs Sunday and Monday struggling to rise above freezing.

Tuesday Night Technical Discussion

Synopsis:

High pressure will continue to dominate over the Mid-Atlantic Region for the first half of the week. A low-pressure system to our west will track over the great lakes and eventually to the north of us, and it's associated cold front will bring scattered rain showers across PA Wednesday night into early Thursday morning. Behind the front a northwest flow will provide cold air advection and a chance for scattered lake effect showers for northwestern counties Thursday night through Friday. High pressure will return to the area and provide mostly clear skies and slightly warmer conditions for the weekend.

Short Term: (Tuesday night through Wednesday night)

Cloud cover tonight should moderate temperatures, with the 18Z 12km NAM indicating mid to upper 30's for the western half of the state and low to mid 40's for the eastern half of the state due to low-level clouds associated with the southeasterly flow off the ocean. The mean southerly flow will persist during the day Wednesday providing warmer temps ahead of the cold front associated with the low-pressure system to our west. This low pressure will slowly make its way toward the great lakes and begin to push the high pressure currently over the region off the coast. The system will pass north of the region and its associated cold front will cross the state. The 18Z GFS and NAM, as well as the 21Z SREFMEAN, agree with the timing of the cold front to reach western counties by Thursday around 06Z and the pre-frontal precipitation to reach northwestern counties by Thursday at 03Z.

Long Term: (Thursday into the weekend)

As the cold front crosses the region it will bring widespread scattered rain showers for the entire state. A northwesterly flow will follow behind the front and initiate cold air advection as the 540dm line dips just south of the state Thursday night into early Friday, indicated by the 18Z NAM and GFS. The northwesterly flow will also provide a chance for scattered lake effect rain/snow showers Thursday night through Friday morning, mainly for the higher elevations in the northwestern portion of the state. High pressure will return to the region Friday night, but quickly move off the coast by Saturday evening. Another low pressure will move well north of PA and an associated shortwave will traverse New England on Sunday. Precipitation is not likely anywhere in the state and high pressure will follow in the wake of the shortwave passage for the beginning of the workweek.

~ A.J. Herbert

Monday Afternoon Technical Discussion

Monday Afternoon Technical Discussion

Synopsis:

Clear skies and average temperatures will dominate out forecast for much of this week with the exception of Thursday when some precipitation will move into the area. Friday looks to be a nice day as well

Short Term: (Monday night through Tuesday night)

A high pressure system located off the Maine coast will dominate our forecast during this time period. Associated with this high pressure system is a ridge going down the spine of the Appalachian Mountains, so much of the eastern seaboard is experiencing tranquil weather during this time period. Our sjies will be mostly sunny during this time period. Temperatures are expected to be climatology average during this time period with highs in the 50s and lows in the 30s. 

Long Term: (Wednesday through Friday)

The same pattern dominated by the short term forecast will dominate the long term forecast too until Thursday when a cold ! front will approach the area. As of right now, the timing of t! his cold front looks to be that is will arrive in the area by Thursday morning. Once this cold front moves through, high pressure will approach from the southwest and skies will clear out for Friday. 

Tuesday Night Technical Discussion

Synopsis:

High pressure will continue to dominate over New England for the middle of the week. A warm front associated with a low-pressure system to the west will begin to push north through the state Wednesday night into Thursday and bring a chance for scattered rain showers for the northern half of the state. A cold front will follow in the wake of the warm front and make its way east across the state, early Friday, which will provide wide spread rain showers for the entire region before high pressure returns for the end of the weekend.

Short Term: (Tuesday night through Wednesday night)

Short waves just to the north and south of the state will provide a slight chance for scattered showers tonight in those respective areas of the state, as well as eastern counties. Lows will be warmer than previous nights with temperatures ranging from mid 30's in northern counties to mid to upper 40's in the extreme southern portions of the commonwealth, indicated by the 18Z 12km NAM. A chance for fog in the lower Susquehanna valley will be present Wednesday morning. High-pressure remains over the region Wednesday before it moves off the coast and a warm front approaches from the south late Wednesday night.

Long Term: (Thursday into the weekend)

As the warm front makes its way north across the state, scattered showers will be possible Thursday morning, especially for the northern and northwestern counties. The low-pressure system associated with this warm front will move to our north late Thursday night into Friday and the attached cold front will bring rain showers for the entire state. The 18Z NAM gets the precipitation in the far western counties by 3Z, while the 18Z GFS and the 21Z SREF keep light precipitation over the majority of the state after the passage of the warm front and before the cold front passage. The front will move quickly and exit the state by the afternoon, providing clear skies and cooler air via cold air advection in the wake of the cold front. A secondary cold front and trough will move into the region Saturday evening bringing colder air and a northwest flow off the lakes. This will provide scattered lake effect rain and snow showers for the northwestern counties Saturday evening into Sunday. High pressure will return for the beginning of the workweek and warmer air will follow.

~ A.J. Herbert

Forecast Discussion 10/28 Afternoon

High pressure is creating some cooler and clearer conditions to start the week, but a cold front will make its way to Pennsylvania later this week for a wet start to the weekend.

Short-Term: Mon-Wed
High pressure sitting over the Gulf will bar any clouds from building in over PA for Monday and Tuesday. Clear skies and cool temperatures can be expected for Tuesday. Moist air from the south may interact and mix with cooler air from the north to create some cloud cover or potential showers for Tuesday night heading into Wednesday. Although, any showers produced from this will likely be short-lived, and skies appear to clear out by Wednesday morning.

Long-Term: Wed-Fri
Another day of clear skies is expected for Wednesday, but with warmer temperatures due to warm air being funneled northward from the Gulf into Pennsylvania ahead of a front. Wednesday night and early Thursday morning will be greeted with a cold front making its way across the country, with rain dominating the forecast for the next 2 days. Temperatures remain warmer as surface heating will be trapped due to cloud cover, and little chance for evaporational cooling due to the sheer predicted size of the oncoming front. Rain is expected to break Saturday morning as the front finally moves out of Pennsylvania.

Tuesday Night Technical Discussion

Synopsis:

In the wake of the cold front, the associated low pressure system will move off the coast and provide a northwesterly flow off the great lakes. This will set up a lake effect snow event for northwestern counties and the Laurel Highlands through Friday. High pressure will approach the region Saturday and the northwesterly flow will weaken. However, a second low pressure system will pass to the north of the state, providing a chance for more lake effect snow showers for the northern portions of the state for the end of the weekend due to a mean westerly wind off the lakes. High pressure and a more zonal flow will dominate for the beginning of the work week.

Short Term: (Tuesday night through Wednesday night)

Cold air advection will continue to drop temperatures across the state for the majority of the week. Much of the state is expected to have low temperatures in the mid to upper 30's Tuesday night with high temperatures on Wednesday only reaching the mid to upper 40's with a few low 50's in southeastern counties according to the 18Z 12km NAM. The northwesterly flow will also provide northwestern PA and the Laurel Highlands with a chance for lake effect snow showers Tuesday night through Wednesday night. The 20Z HRRR is showing some rain showers in the southeastern portions of the state Tuesday night and into Wednesday morning.

Long Term: (Thursday into the weekend)

The northwesterly flow and the associated lake effect snow will persist through Friday. Overnight Friday, high pressure will begin to approach the state and the northwesterly flow will weaken. A low pressure system to the north will approach the region but remain north and the associated cold front will prove a mean westerly flow off the lakes. This will lead to a chance for lake effect snow for northern counties. High pressure will move into the region Sunday night and lead to a drier start to the workweek.

~ A.J. Herbert

Tuesday Afternoon Discussion

Clouds and much cooler temperatures are set to take over Pennsylvania over the course of this week. A strong cold front will move in on Tuesday and bring us a major shot of cold air. Temperatures will fail to get out of the 40's across parts of the state and overnight lows could easily fall below freezing especially in the northern portions of the state. Wednesday and Thursday also bring us the first chance for a few snow flakes as rain and snow showers will push across the state.

A massive, upper-level trough will continue to dig through the eastern half of the country through the rest of the work week.  Shortwave impulses eastward across the Great Lakes will be the primary mechanism for any small disturbances we see in PA.  These pockets of energy will excite fast-moving clipper lows sweeping through the northeast.  With high pressure building in from the SW behind these lows, this pattern will be conducive for the continued strengthening of an isabollaric wind in PA.  Ultimately, the upper-level trough exits after the weekend while another trough stretches down to AZ out west and spins up its attendant surface low in the Plains.  A significant cold air damming event also seems possible with a slowly departing high in the NE circulating cold air into the eastern Appalachians.  Fortunately, the surface low looks to head up through the Lakes and into Canada and only affect the NE with the trailing cold front.  Should it shift farther east, though, we could see the setup for some snow accumulation on Halloween in the NE.  This warrants further monitoring.

Forecast Discussion 10/21 Afternoon Shift

The sunny skies from Monday will quickly become a thing of the past as a cold front brings colder, wetter weather to the commonwealth. Showers, chilly temperatures, and potentially even some snow flurries can be expected this week.

Short Term
A cold front will move through the state Monday night into Tuesday, bringing some scattered showers to the western portions of the state for Tuesday morning. Skies should otherwise remain mostly cloudy for Tuesday afternoon and evening as showers will likely dissipate as they move eastward. Temperatures should remain in the mid-40s for the State College area, with areas around Pittsburgh and Philadelphia reaching slightly above 50 degrees. Tuesday night into Wednesday sees the approach of more showers, which may produce some mixed precipitation by Wednesday morning.

Long Term
With the 540-line dipping south into Virginia, some snow flurries are possible for Wednesday morning. By noon, however, it will creep back up into Pennsylvania and any flurries will turn to rain. Showers will persist until Wednesday evening, leaving mostly cloudy skies. Temperature patterns again remain around the mid-40s to low 50s for Pennsylvania for this time. Thursday morning has the potential for a few scattered showers, although not likely. Mostly cloudy skies and chilly temperatures similar to those of Wednesday look to be the pattern for Thursday and Friday, with a little less cloud cover on Friday, as a more zonal pattern takes over and pushes the cold front further east.

Monday Morning Technical Discussion

Synopsis

A series of small disturbances will affect the Commonwealth throughout the week.  The first, a cold front passing through the state on Tuesday, will bring light rain mostly to the western third of the state.  On Wednesday, a system tracking up the coast will bring rain to the Southeast while a less organized system moves in from the west, bringing more light rain and possibly even snow showers.  Lake-effect rain and snow showers are likely on Thursday and into Friday in the Northeast.  Temperatures will drop after Monday, hanging mostly in the low 50s and 40s throughout the week, although highs in the Southeast will likely stay in the mid-50s.

Short-Term (Through 0z Thursday)

A cold front passing through the region on Tuesday will bring the Commonwealth its first prolonged stretch of chilly air, with highs in the low 50s and high 40s.  Precipitation is likely to remain in the western third of the country as the system looks to be deteriorating as it approaches the mountains.  The GFS and NAM both expect a coastal low to affect the Southeast on Wednesday, although the NAM is a bit more robust with its QPF amounts.  Some snow is possible in the northern and western parts of the state and at higher elevations, but accumulation is unlikely.

Long-Term (Past 0z Thursday)

Following the two systems on Wednesday, no organized precipitation is likely.  The only likely precipitation will be in the northwestern part of the state, where lake-effect rain and snow showers will affect the region.  Temperatures will remain in the low-50s and high 40s late in the week, with Philadelphia in the mid- to high-50s.

~Patrick Higgins

Tuesday Night Technical Discussion

Synopsis:

High pressure will continue to drop off through Wednesday as a cold front reaches the state Wednesday night. The front will stall over the state Wednesday night into Thursday and bring showers to the region Wednesday night through late Thursday night. High pressure will follow the passage of the front and provide clear and dry conditions with cooler temperatures for the end of the week into the weekend. A deep trough will dig into the region Saturday night into Sunday along with a cold front passing north of the region and provide a chance for scattered showers along with colder air.

 

Short Term: (Tuesday night through Wednesday night)

Pressure will continue to drop as a cold front approaches the area. High dew point temperatures and light winds indicated by the 10m winds on the 18Z 4km NAM will provide a chance for low-level clouds and fog. The 18Z NAM and GFS, as well as the 18Z 3km HRRR, agree with the front reaching northwestern counties by around 9Z. The showers will be spotty across the state as the front stalls and weakens Wednesday night.

 

Long Term: (Thursday into the weekend)

A separate low-pressure system to the south will move along the stalled front northeasterly across the state Thursday night. Behind this disturbance, high pressure will follow, bringing clear and dry conditions with cooler air. The 18Z 12km NAM has low temperatures reaching the upper 30's for the extreme western portions of the state. These cool and clear conditions will persist into Saturday, when a deep trough will approach the state from the west along with a cold front. The front will pass near the state and provide a scattered chance of showers, especially for northwestern counties Saturday night. Cold air advection will follow behind the passage of the low-pressure system to the northeast, which will be amplified by the deep trough of 500mb heights. High pressure will build over the region for the beginning of the workweek.

 

~ A.J. Herbert

Synopsis:

Relatively warm and cloudy weather will be the story across the state for Tuesday and Wednesday. Showers and some steady rain will move in for Thursday and Friday looks to be mostly a washout. All is not lost however as things will clear up for Saturday. A blast of cold air will then move into the region towards the end of the weekend.

A pair of pesky upper-level shortwave troughs will be the source of the rain showers moving through the region on Thursday and Friday.  Afterward, a persistent, upper-level trough will settle over the eastern US and feed colder, Canadian air right over the Northeast into next week.

Forecast Discussion 10/14

The scattered showers that came through State College on Monday morning look to be setting the tone for most of the week ahead. Cloudy skies and occasional showers can be expected up until the weekend.

Short Term (Mon-Wed)

High pressure building in from the south looks to be creating some clearer conditions after the cloudy skies and occasional showers experienced on Monday. Tuseday looks to be a more pleasant day with temperatures ranging from the low 60s to about 70 degrees for most of the state. A large low pressure system up in Canada then takes control of the overall synoptic pattern for the northeast United States, bringing cloudy skies and rain for the next few days.

Long Term (Wed-Fri)

The forecasted weather pattern for earlier in the week looks to be repeating again for Wednesday - Friday. Rain, which may be heavy at times, is in the forecast for Wednesday due to a strong trough extending down from a low pressure center in Canada. After showers move out Wednesday, Thursday has a brief break in rain, but cloudy skies remain as atmospheric moisture content remains rather high. Another band of clouds and rain will be moving through Thursday night heading into Friday. On Friday, high pressure takes over again, and creates some more pleasant weather for the start of the weekend.

Tuesday Night Technical Discussion

Synopsis:

High pressure will continue to build over the northeast for the rest of the week. A coastal low will slowly make its way up the coast and its associated bands of rain will approach the region and provide a chance for showers Wednesday night through Friday night. A cold front will approach the region Sunday from the west and push the coastal low east and provide a slight chance for scattered showers.

                                                      

Short Term (Tuesday night through Wednesday):

High pressure will sit over the northeastern states dry air, and calm winds will provide clear skies and cool temperatures overnight Tuesday with some areas of frost. Lows could get to the mid to upper 30's for the northern counties and higher elevations but mid to upper 50's for low temperatures in the southwestern counties indicated by the 18Z 12km NAM. Wednesday looks to be another clear day with an easterly flow, which will usher in clouds for the afternoon and evening hours.

 

Long Term (Wednesday night into the weekend):

A coastal low-pressure system will slowly creep up the coast throughout the week and the high pressure over the northeast provide an easterly flow to enhance the regions chance for precipitation Wednesday night through Friday night. The 18Z NAM is indicating a significant event for much of the state; however, the 18Z GFS keeps the majority of the precipitation to our east, as do the majority of the 21Z SREF members. Expect the best chance for precipitation for the southeastern counties. The low pressure will sit on the coast for the weekend but the chance for precipitation is miniscule, as the easterly flow will diminish and the high pressure will provide dry air aloft. A cold front will approach the state from the west on Sunday, which will push the coastal low out to sea and provide a chance for some scattered showers across the state during the day.

 

~ A.J. Herbert

Monday Afternoon Technical Discussion

The cold front dropping down from a low pressure system centered in Northern Quebec will be moving out of the area Monday evening which means an end to the rain and thunderstorms. Skies will clear up as the front moves eastward out to sea. A high pressures system will then approach from the southwest and this will give us very pleasant and sunny weather. The passage of this front means cooler temperatures are on the way too. The above average temperatures we have been seeing over the past few days will be no more as temperatures will return to what they should be for this time of year. This temperature trend will continue for the whole week. Wednesday night, a weak piece of energy will move northward out of the Piedmont region towards Pennsylvania and has the chance to bring some showers to Pennsylvania, especially for southeastern portions of the state. This piece of energy will keep skies cloudy for Thursday. This disturbance will move out of the region come Friday as skies will return to Partly Cloudy. The southeastern part of the state has the chance to see a shower come Friday night though. 

Tuesday Night Technical Discussion

Synopsis:

High pressure will continue to build over the region through Thursday bringing warm and dry conditions. A warm front will threaten to bring scattered showers across the state for Thursday night and Friday. A low-pressure system to the west will move northeast as its cold front will stall on the east coast and affect the region Sunday afternoon into the beginning of next week bringing more widespread showers.

Short Term: (Tuesday night through Thursday night)

High pressure along the east coast will continue to dominate and bring beautiful fall weather across PA. High temperatures could reach the mid 80's on Wednesday in southern portions of the state and low temperatures are likely to remain in the 50's for much of the state Wednesday night, indicated by the 18Z 12km NAM. Expect a chance for some fog in the valleys. A warm front will approach the region Thursday night and bring scattered showers throughout the day Thursday. Both 18Z NAM and GFS are spotty with the showers, especially on Friday.

Long Term: (Friday into the weekend)

Scattered showers will be widespread Friday and exit the state by late Friday night. The state will remain in the warm sector and warm air advection should keep temperatures warm on Saturday. The low-pressure system to our west will make its way northeast into Canada and the associated cold front will move east across the state. The 18Z GFS has the frontal precipitation reaching the western counties by 18Z Sunday. The front will make its way across the state but stalls on the east coast, which could enhance the total amount of precipitation we get from the system from Sunday night into the beginning of next week.

~ A.J. Herbert

Technical Discussion 9/30 Afternoon Shift

Another pattern of clear, sunny skies and above-average temperatures appears to be in store for the week ahead. A look at the weekend, however, appears to show some wetter weather on its way.

Short Term (Mon-Wed)
A mix of sun and clouds Monday sets the tone for the week ahead. A weak cold front ahead of a weak trough may bring some clouds to the western portions of the state Monday evening heading into Tuesday, but this front will likely dissipate. High pressure-air then takes over for the majority of the week ahead. Temperatures are predicted to climb into the mid-70s for most of Pennsylvania. The urban heat island effects around Pittsburgh and Philadelphia will cause temperatures in the southern corners of Pennsylvania to reach the low-to-mid-80s.

Long Term (Wed-Fri)
A pattern of warm, low humidity air looks to hold its ground for the latter portion of the week. As Friday approaches, however, a high pressure system over the southeastern US looks to change this. Circulation around the high appears to send some moist air from the Gulf of Mexico up to Pennsylvania, which could create some cloudier and wetter conditions. Clouds and rain can be expected for Friday, and are possible throughout the weekend ahead as well. Temperatures are expected to cool down a bit with the arrival of this moist air as well.

Monday Morning Technical Discussion

Synopsis

Another week of dry, mostly sunny weather awaits the Commonwealth.  With the exception of a weak disturbance that could bring showers to western half of the state, mostly sunny skies and temperatures steadily rising from the high 60s to low 80s will affect Pennsylvania throughout the week.   A weak warm front will move through the region on Friday, bringing with it a chance of showers, but significant precipitation is not expected until the passage of a cold front on Sunday.

Short-Term (Through 0z Thursday)

Both the GFS and NAM agree that mostly sunny skies and temperatures in the high-60s and low-70s will affect the state on Monday.  Though both models are indicating cloudier conditions on Tuesday due to a low pressure system passing to the north, only the NAM (particularly 06z Hi-Res NAM) is indicating showers for the western half of the state.  Temperatures will be mostly in the 70s on Wednesday, with skies clearing once again.

Long-Term (Past 0z Thursday)

Thursday and Friday will again see generally clear skies and temperatures in the high 70s and low 80s.  A weak warm front is predicted by the GFS to pass through the state Friday evening, but little rainfall is associated with this front.  Skies will begin to cloud on Saturday as a result of an incoming cold front, which is predicted to pass through the state on Sunday, bringing with it widespread showers and more seasonally cool air.

 

~Patrick Higgins

Friday PM Technical Discussion

Synopsis:

With the exception of a cold front approaching from the west and a coastal system expected to remain well off-shore, the next six days will be relatively quiet across the Commonwealth. Clear skies, light winds, warm days and cool nights greet the end of September & start of October.

Models Used: 12z GFS, 12z ECMWF, 9z & 15z SREF, 12z NAM, and 12z Hi-Res NAM

Models are in general agreement with the overall synoptic pattern this week & precipitation probabilities for Sunday Night & Monday, with the SREFs best handling the precip. timing since only a few hundredths are expected to fall over the Allegheny Plateau on Monday, which are not being picked up by the deterministic models (NAM & Hi-Res NAM). Most of the rain (around a tenth-inch) will occur in Erie and Crawford counties Sunday night into Monday morning, and the coastal system will only affect coastal states.

-Jaron

Tuesday Night Technical Discussion

Synopsis:

High pressure will build over the region for the remainder of the week into the first half of the weekend providing pleasant fall weather with cool nights and normal high temperatures. A coastal low could possibly threaten the far eastern portions of the state with scattered showers on Sunday into Monday, and a cold front from the west will make its way across the region bringing scattered showers Monday evening into early Tuesday.

 

Short Term (Tuesday night through Wednesday night):

Calm winds at night and clear skies will provide cool temperatures in the low to mid 30's for higher elevations allowing for some widespread frost to form Tuesday Night. Also expect fog to form Wednesday and Thursday morning as temperatures cool to their dew points. Wednesday will be another day of beautiful fall weather after a cool night as high pressure sits over PA. Temperatures are likely to reach the low to mid 70's in southern counties of the state and mid to upper 60's elsewhere Wednesday indicated by the 18Z 12km NAM.

 

Long Term (Thursday into the weekend):

High pressure will continue to sit over the state Thursday through Saturday providing more pleasant weather with clear skies and calm winds. A coastal low will attempt to throw some moisture towards eastern portions of PA late Sunday into Monday but the 18Z GFS is not showing a chance of it reaching the state. A slow moving cold front will finally make its way across the state Monday into Tuesday bringing some wide spread showers as the long-lived ridge of high pressure finally moves off the coast.

 

~ A.J. Herbert

Forecast Discussion 9/23 Afternoon Shift

A cold front has left temperatures in Pennsylvania cool and autumn-like, and high pressure is set to take over and create very pleasant and sunny conditions for the week ahead.

Short term (Mon-Wed)

Cloudy skies Monday morning have dissipated thanks to a high-pressure ridge moving into Pennsylvania. This high-pressure ridge will bring very little moisture content with it, setting up for low humidity with little to no cloud cover. The absence of clouds will allow for temperatures to steadily climb through the 70s heading later into the week. Low temperatures overnight will be in the low 40s and possibly the 30s for the northern portions of the state, so frost is a possibility.

Long term (Wed-Fri)

Sunny skies will persist through Wednesday. A trough extending down from Canada will begin to make its way east, but will most likely weaken and dissipate when matched against the ridge currently over Pennsylvania, and any low-pressure air will be diverted south, leaving the same weather pattern in place through the weekend. Temperatures will be a bit warmer for September, reaching the mid-70s in most areas of the state, with overnight lows in the 40s.

Monday Morning Technical Discussion

Synopsis

Following Saturday's slow-moving cold front, high pressure will continue to build into the Commonwealth, leading to mostly sunny skies and temperatures in the 60s and low 70s for most of the state.  Some areas may experience patchy frost, particularly Bradford, as low temperatures will often reach down into the 30s and 40s.  Additionally, dew points will be very comfortable, ranging from the low 30s to low 40s.  High pressure will remain entrenched in the region throughout the week, with the only threat of precipitation coming on late Sunday afternoon. 

Short-Term (Through 0z Friday)

Both the GFS and NAM agree that skies will be generally clear and temperatures will rise through the 60s on Monday and Tuesday before plateauing in the low- to mid-70s for Wednesday, Thursday, and Friday.  At times, clouds will pop up overnight, limiting the downward reach of the low temperatures, but models generally agree that most lows will be in the 40s.

Long-Term (Beyond 0z Friday)

The NAM's forecast period ends with temperatures still hanging in the 70s and skies remaining clear.  Over the week, the GFS is indicating that another cold front will pass through the region, bringing with it precipitation and another cool down for next week. 

~Patrick Higgins

Tuesday Night Discussion

Synopsis:

High pressure will continue to build over the state and clear skies and dry conditions will follow. High temperatures will rise throughout the week until a cold front slowly moves across the region Saturday into Sunday morning bringing widespread showers throughout the weekend.

 

Short Term: (Tuesday night through Wednesday night)

As a ridge of high pressure continues to build over PA, comfortable conditions and clear skies will persist. Each day the high temperature will increase owing to the clear skies and lack of any other negative influence on temperature. High temperatures look to reach the upper 70's across the entire state by Friday indicated by the 18Z 12km NAM, with low 80's possible in southwestern counties. Clear skies and calm conditions at night will allow for significant radiative cooling throughout the week with higher elevations reaching the mid 30's Tuesday night. As the high pressure moves off the coast Friday and the low pressure begins to approach the area, a southwesterly flow will develop and help increase the temperatures through advection for the day, along with some moisture advection to provide a few more clouds. A cold front, associated with a low-pressure system in the Northwest progresses east throughout the week.

 

Long Term: (Thursday into the Weekend)

The high pressure that builds over the region throughout the week helps strengthen the low-pressure system to our northwest, which eventually moves northeast into Canada, as the ridge slowly moves off the coast early Friday morning. The low-pressure system looks to eventually become a cutoff low late Friday night indicated by the 18Z GFS. As the warm front associated with the system to the north becomes stagnant Friday afternoon, scattered showers are possible for western portions of the state. Otherwise, the majority of the precipitation will fall between Saturday afternoon and early Sunday morning as the cold front moves across the state. In the wake of the cold front high pressure will once again build over PA for the beginning of the workweek providing slightly lower temperatures attributed to a rather shallow trough.

 

~ A.J. Herbert

Forecast Discussion 9/16/13 Afternoon Shift

A very pleasant week is in store for the commonwealth, with seasonable temperatures and sun lasting until later in the week. A low pressure system lurks north of the border, ready to drag a trough bringing showers and thunderstorms through Pennsylvania.

Short Term (Mon-Wed)

Showers Monday morning effectively drained the atmosphere of any moisture still present, setting up for a dry and sunny forecast for the next couple of days. A high pressure ridge looks to be taking the place of the trough from the previous weekend. Temperatures will steadily climb through the 70s across the state, while southern portions of Pennsylvania may be slightly warmer. Sun and possibly a few passing clouds are the story for the earlier portion of the week, so it looks to be a pleasant forecast.

Long Term (Wed-Fri)

Wednesday evening heading into Thursday sees a slight increase in the relative humidity in the lower levels of the atmosphere. A few clouds are possible throughout the day and night on Thursday for most of the state. Temperatures will reach their peak on Friday, with areas around Philadelphia and Pittsburgh reaching close to 80 degrees. Friday evening sees the progression of a cold front, bringing showers and possibly some strong thunderstorms for Friday heading into Saturday as well.

Monday Morning Technical Discussion

Synopsis

High pressure will dominate weather for the week as a cold front moves passed us. Bring high temperatures in the 60's and 70's to the area.

Short term

Rain possible early on Monday after that the skies clear as the high pressure builds in over the area. This will gives temperatures with highs in the mid to upper 60's and lows in the 40's.

Long term

The high pressure sticks with us and begins to move out at the end of the week giving the possibility of thunderstorms on Friday. This will cause the high temperatures to be in the low to mid 70's and low temperatures to increase to the 50's.

John Anthony (J.W.)

Synopsis:

After a weekend of fall-like temperatures, a weak front will pass through the commonwealth on Monday bringing clouds and a few showers to the majority of the state.  Temperatures will stay in the 60s on Monday as the sun will find trouble breaking the clouds.  Following the passing of the front, winds will turn northerly drawing cool air throughout the whole state on Monday night.  High pressure will then build across the Northeast associated with cool temperatures and sunny skies for the rest of the work week.

Short Term:

Both the 18z NAM and GFS show a weak disturbance crossing the state from Northwest to Southeast on Monday. Rainfall amounts associated with this precipitation will be minimal.  Most of Pennsylvania should expect cloudy skies and a few showers before the front passes.  Temperatures on Monday will hover in the upper 50s and 60s, with cooler temperatures in the Northwest regions of the State.  On Monday night, temperatures will dip into the 40s across the state, and as low as the mid-30s in northern areas of Pennsylvania. 

Long Term:

It will be an uneventful week of weather after Monday as high pressure will build over the Northeast.  Temperatures will hover in the Mid 60s across the state, with warmer temperatures by Thursday and Friday.  Night time temperatures will dip into the upper 30s and 40s for the majority of the state.  Expect sunny conditions and low humidity with dew points in the 40s.

Maximilian Vido

Friday Afternoon

Synopsis:

After the powerful series of cold fronts touched off severe thunderstorms yesterday, cooler weather is on tap for the weekend into early next week as high pressure will settle in. There will be a much weaker front passing through on Monday, which will touch off a few showers.

Models Used: 12z NAM, GFS, ECMWF, SREF; Hi-Res NAM not needed

All the models were all in agreement with the overall synoptic pattern over the next five days. High pressure will settle in overnight, clearing out the clouds and instability-driven, lake-enhanced showers. The high will move offshore Sunday AM and the southerly flow will advect in some warmer air. The GFS, NAM, & Euro each had the timing of this front for a wee hours to late afternoon passage (going from west to east). And high pressure will settle in for next week.

-Jaron Breen

Tuesday Night Technical Discussion

Synopsis:

 

In the wake of a high pressure moving off shore, a southerly flow is advecting warmer and moist air into the region. The unseasonably warm and humid air will remain until Thursday when a cold front will make its way across the state, bringing widespread rain showers. Cooler air will follow the passage of the cold front for the end of the week into the weekend.

 

Short Term: (Tuesday Night through Wednesday Night)

 

The southerly flow associated with the Bermuda high off shore will continue to bring warm and humid air into the region until Thursday. There will potentially be warmer temperatures nearing 90 degrees in many locations after a mild night Tuesday night compared to Monday night, as well as a chance for widespread scattered showers and storms tomorrow afternoon during max heating.

 

Long Term: (Thursday into the Weekend)

 

Both 18Z GFS and NAM are agreeing with the cold front to move into northwestern PA by 12Z Thursday and exiting the Philadelphia area around 03Z Friday. The 21Z SREF also agrees with the timing of this front and all three models agree with significant rainfall and scattered storms accompanying the frontal passage. The 18Z 12km NAM has some scattered showers across northwestern and northern PA associated with the mean northerly flow off the lakes. Cooler and drier air will follow this front and bring temperatures to a seasonable value with highs averaging in the 60's, as high pressure will build over the region for the end of the week into the weekend.

 

~ A.J. Herbert

Monday Evening Forecast

Synopsis:  Pennsylvania will be experiencing warmer temperatures early this week dying down into the 60s on Friday. The majority of days this week will see sun with a chance of rain on Wednesday and a chance for thunderstorms for much of the state on Thursday. Nothing truly exciting is currently happening around the nation except for heavy rains and flash flood warnings in the 4 Corners Region out West.

Outlook: Consistent southerly winds advecting moist, hot air will cause temps and dewpoints to spike well above average tomorrow and Wednesday. This circulation pattern will be associated with a developing low to the west that will move NE over the Great Lakes.  We won't see much in the way of storms from this system as its associated (and weak) fronts move through on Wednesday.  GFS shows it merging with another developing low in Ontario and strengthening as the combined low heads eastward.  The cold front associated with this system WILL impact PA on Thursday, bringing storms (some strong) in the early afternoon.  Afterwards, a NW flow sets up, bringing chilly temperatures with highs in the 60's across much of the commonwealth.

Forecast Discussion 9/9/13 Afternoon Shift

Much warmer temperatures are in store for Wednesday and Thursday, but a cold front is ready and waiting to bring some showers and thunderstorms, and return those temperatures to normal.

Short Term (Mon-Wed):

Cloudy skies Monday will clear up and then set the stage for summer-like temperatures. High temperatures across the state are expected to be in the high 80s, and low 90s around the more urban areas of the state. Skies will remain mostly clear for Tuesday. However, Wednesday sees the approach of a cold front extending down from a low pressure air mass over Canada.

Long Term (Wed-Fri):
Wednesday will bring scattered showers and thunderstorms to the state. Thunderstorms could grow stronger with the presence of high CAPE values in the lower levels of the atmosphere. Thursday brings a continuation of these showers and thunderstorms. Temperatures, however, drop into the high to mid-70s behind the advancing cold front. Friday is set up as a much more seasonable day, with temperatures in the mid-60s and clearer skies. This same pattern of clear, autumn-like weather appears to be the pattern heading into the weekend as well.

Monday Morning Technical Discussion

SYNOPSIS

High pressure will begin to move away from the region as a low pressure system moves through the Midwest.  Following the passage of the warm front on Tuesday afternoon, higher, summerlike temperatures will again affect the state.  Thunderstorms will be possible following this warm front, but the greatest convection will come on Thursday, when a cold front will pass through the region.  High pressure will surge back into the region on Friday and Saturday, bringing with it a return to autumnal temperatures.

Short-Term (Through 0z Thursday)

High pressure is expected to erode throughout the day on Monday as a low pressure system approaches from the west.  The 6z GFS moves the warm front through the region a bit quicker than the 6z NAM, but both models expect warm air advection to propel temperatures into the 80s across the state on Tuesday, with 90s possible in the Southeast.  Both models offer a chance of precipitation as the warm front passes, with the NAM expecting more precipitation, due to the later passage of the front and resulting increased chance of convection; precipitation is unlikely to be widespread, however.  Similar conditions will exist on Wednesday, with a chance of thunderstorms and summerlike temperatures in the 80s and low 90s.  Expect conditions to become stickier on Wednesday as well.

Long-Term (Beyond 0z Thursday)

Temperatures will remain in the 80s for most of the state on Thursday, but will be limited by a strong cold front that is expected to pass through the region in the afternoon and evening.  The GFS is delaying this cold front a bit more than the NAM, allowing for more heating and consequently more convection.  Following Thursday's potentially strong storms, high pressure will again fill into the region.  Clear skies and temperatures in the 60s and 70s can be expected throughout the state on Friday and into the weekend.

~Patrick Higgins

Sunday Night Technical Discussion

Synopsis

 

A warm front pushes upward across the state on Tuesday, creating a southerly flow. This front will cause temperatures to rise back into the mid-80s. The unseasonable temperatures will not last long however, as a cold front follows behind on Thursday. In between the fronts, we should expect to see some storms.

 

Short Term (through 12Z Tuesday)

 

The high pressure system lying over the state on Monday keeps the cool, dry conditions for the beginning of the week. Come midday on Tuesday, the direction of airflow switches direction as a warm front drapes north. We will see a return of the summer-like, humid air for the midweek.

Long Term (through 12Z Friday)

The warm temperatures continue through Tuesday and Wednesday. As a cold front approaches, there should be some storms throughout the state on Wednesday and possibly into Thursday. As the cold front passes, an air mass over Canada drops down into the state and drops temperatures back down. We get back into the comfortable fall-like conditions. Friday should be a pleasant day leading into the weekend.

-Joshua Gugel

Wednesday Night Technical Discussion

SYNOPSIS

A weak cold front will alter Thursday's weather pattern slightly, despite a relatively low risk of precipitation. This will set up for very cold overnight lows into early Friday. High pressure will define the weather picture heading into the first half of the weekend, while the next FROPA on Sunday could bring at least a small amount of rain to most of Pennsylvania.

SHORT-TERM (THROUGH 12Z FRIDAY)

A weak cold front is expected to slide into northern Pennsylvania early Thursday morning. 21z SREF shows the greatest chance of measurable precipitation just crossing the PA/NY border right around sunup on Thursday. Even at that, it seems like a long shot to see measurable precip at any station perhaps besides KBFD.  Temperatures will be moderated by the front on Thursday, though, with highs appearing to be capped in the low 70s across the state at best. Temperatures will also fall to very cold levels Thursday night into Friday morning, with lows dipping into the 30s in parts of Northern PA (GFS MOS gives KBFD a low of 29 Thursday night, while KUNV gets a still chilly 41). The risk of frost seems relatively low, but it will be a chilly start for almost everyone.

LONG-TERM (BEYOND 12Z FRIDAY)

The generally calm weather period continues through the first half of the upcoming weekend with high pressure sliding across the state on Friday and positioning itself off the Delmarva on Saturday. This will usher in some WAA for Saturday boosting temperatures back to the upper 70s across much of the state. The next rain maker, such that it is, enters the picture on early Sunday with a cold front stemming from a low way up in eastern Quebec. The 12z Euro keeps the rain risk around longer, while the 18z GFS seems to present the possibility of higher rainfall amounts. Another large ridge of high pressure along with rising heights should mean the start of next week is pleasant as well.

~Devin Boyer

Tuesday Night Technical Discussion

Synopsis:

 

As the cold front continues to move off the east coast, northwest flow and the associated high pressure will provide lower temperatures and drier air for the rest of the work-week. A weak cold front with little moisture will provide a chance of showers during the weekend before high pressure builds back in on Monday.

 

Short Term: (Tuesday Night through Wednesday Night)

 

Clouds will clear Tuesday night, as the upslope flow of warmer air off the lakes will die down with the winds. High pressure will begin to move into the state from the southwest Wednesday and a westerly flow with more sunshine will allow temperatures to reach the mid to upper 70's across much of the state. During Wednesday night and into Thursday morning a secondary cold front will move southeast across the state with little moisture predicted by both the 18Z NAM and GFS, as they keep most of the precipitation in New York.

 

Long Term: (Thursday through the Weekend)

 

High pressure will dominate with a northwesterly flow for Thursday and into Friday morning. Friday morning will be very cool and with the passage of the weak cold front, low-level moisture may be present and could help provide frost for the northern portion of the state. As the center of high pressure moves southwest and passes over the state on Friday clear and comfortable conditions will follow as the ridge sits over the region into Saturday. The 18Z GFS is showing a weak cold front from Canada dropping down behind the ridge on Sunday and providing the chance for scattered shower or storm. Otherwise, high pressure will begin to build back in from the north on Monday.

 

~ A.J. Herbert

Monday Evening Forecast

Synopsis:

Clearing skies will lead to a much more pleasant Tuesday. High pressure is forecasted to move into the region for the rest of the week and bring ample sunshine and decreasing cloudiness. This pattern will be with us for the rest of the week and weekend with very little chance of precipitation.

Discussion: An upper-level omega block will build over the central US tomorrow and persist through the beginning of the weekend. The only disturbances we will see during the forecast period will come from isolated shortwave pockets of energy ejecting from the Great Lakes.

Monday Morning Technical Discussion

Synopsis:

Skies will remain cloudy throughout most of the Commonwealth as a front approaches from the west.  Showers and thunderstorms may accompany this front, but it appears to be weakening as it moves eastward.  As a result, anything more than light rain will likely be confined to the southeastern quarter of the state.  After the front passes overnight, clearer, warmer, and drier conditions will move into the region.  These conditions will remain in the area throughout the week and into the weekend, bringing temperatures in the 70s, lows in the 50s, and much lower dew points. 

Short Term:

A front approaching from the west will cross the state in the afternoon and evening, pushing the present moist air mass out of the area.  Although storms were previously expected with this front, it appears to be weakening in Ohio, as not much rain or even high clouds are indicated on satellite and radar.  This, combined with the fact that both NAM MOS and GFS MOS are predicting cloudy conditions for all but the southeastern quarter of the Commonwealth, indicates that additional convection will be limited and  rain will either not materialize or will be light as the front moves through the state.  Showers and thunderstorms are possible near Harrisburg and Philadelphia, however.  After the passage of the front, models and MOS agree that high and low temperatures will be fairly steady in the 70s and 50s, respectively.

Long Term:

High pressure will build into the state following the passage of the front, leading to markedly lower temperatures and dew points.  Some clouds will linger on Tuesday, but starting Wednesday, clear skies are expected.  Temperatures will remain relatively steady in the 70s, with State College hanging around 75 and the Southeast approaching 80.

Patrick Higgins

Synopsis:

Unsettled weather will remain in the area on Monday after an eventful day of weather on Sunday.  Strong thunderstorms moved northeast across the state bringing lightning and heavy rain to many areas in the southern and eastern parts of Pennsylvania.  The cold front will linger on Monday sparking more thunderstorms in the same areas as Sunday's storms.  After the front passes there will be a welcomed change in the weather, with low humidity and seasonable temperatures for the rest of the week. 

Short Term:

Thunderstorms will continue to cross the state Sunday night associated with a moist, tropical air mass.  The unsettled weather will remain in the eastern part of the state on Monday before finally moving out in the evening.  Dew points on Monday will range from the mid 60s to 70 signifying the uncomfortable conditions that will be felt across the state.

Long Term:

High pressure will build Tuesday bringing a noticeable change in the weather for the rest of the week.  Cooler and drier air will set in throughout the Northeast with dew points in the lower 50s and temperatures in the mid 70s.  The conditions should be welcomed after a week of above average temperatures and humid conditions.  Abundant sunshine will be felt from Erie to Philadelphia as the high pressure builds over the Ohio Valley.           

Maximilian A. Vido

Thursday Afternoon

Synopsis:

Apart from a few leftover showers in eastern PA, look for partly to mostly cloudy skies under warm and humid conditions for the end of the work week. For the weekend, expect showers and thunderstorms as a cold front slows on approach, finally passing through on Monday night, which will make things cooler and less humid for the middle of next week.

Models Used: 12z GFS, 12z NAM

Short-term:

High pressure at 700 mb & higher will be enough to keep the western two-thirds of the state dry, but high relative humidity throughout the lowest 10,000 ft (3,000 m) due to the weak cold front will keep clouds around for the entire Commonwealth and the weak cold front has slowed offshore, leading to showers for the southeastern parts of the state.

Long-Range:

As a cold front builds strength along the Mississippi River, it will slowly head northeast over the next few days. The offshore cold front hasn't done much to drop humidity, so there's enough moisture for scattered showers during the weekend. When the front gets closer, forcing will enhance the rainfall and lead to thunderstorms.

-Jaron Breen

Tuesday Night Technical Discussion

Synopsis:

The ridge to our west will remain fairly stationary and the short wave energy will continue to produce scattered thunderstorms through the middle of the week. With the return of a northwesterly flow, a clearing will occur for the end of the work week and provide pleasant conditions for Friday and into the weekend. A weak warm front will make its way across the state along with the chance for scattered showers and storms for the weekend.

Short Term (Tuesday Night thru Wednesday Night):

Scattered showers will continue to make their way across central and western PA tonight and into the early morning hours as energy associated with the shortwave aloft will continue provide scattered storms for Wednesday afternoon for the western and central portions of the state. A mean Northerly flow will return late Wednesday night and drier conditions should follow in reference to the 18Z NAM shows dew points in the low 60's for the majority of the state.

Long Term (Thursday thru Weekend):

A northerly flow will begin to bring much more comfortable and drier conditions for the end of the week. High pressure will build over the region and skies will clear ahead of the weak warm front that will move through over the weekend. The weak front associated with a Low in Canada will bring scattered showers across the area for the weekend.

~A.J. Herbert

Tuesday Afternoon Discussion

Synopsis:

The weather will remain fairly active for the Western portion of the state on Wednesday with a decent amount of rain moving through the area. The Eastern part of Pennsylvania will remain mostly dry with the exception of a shower or two in the afternoon Wednesday. Thursday looks to be a day of clearing for most of the state setting up for a very nice day on Friday. The weekend looks to be pleasant but the possibility of a shower or thunderstorm cannot be ruled out.

Discussion:

We will continue to be under the influence of frequent, shortwave disturbances rotating around the dominant high in the central US.  These pockets of energy will eject over the Ohio River Valley from the Great Lakes region, inducing strengthening surface lows and the chance for strong/severe thunderstorms in portions of western PA tomorrow night.  The atmosphere looks to stabilize a bit from Thursday through the beginning of the weekend with some 500mb NVA, low 700mb RH, and general descent.  A shortwave disturbance could bring some scattered showers Friday night, but the weekend will be a great one with a relatively dry, seasonal airmass settling into place.  In the long term, a possible cold front situation is setting up on the ECMWF and GFS for Monday afternoon.  This is definitely something to look at.

A ridge present across the central United States continues to dominate the weather for the country. Several pockets of higher vorticity located on the northern portion of this ridge will affect the Eastern United States. Mesoscale thunderstorm events will be associated with these which could lead to some severe weather especially in the Ohio Valley. The ridge will become less amplified going into the weekend will decrease the chance for any major thunderstorm activity and decrease any significant any positive vorticity advection over the Great Lakes and East Coast.

 

A long region of low pressure will affect the region throughout the next few days. It is a result of the large upper level circulation leading to several pieces of upper level energy moving through the area. This means will see several chances for precipitation to occur as a result of these bits of higher vorticity. 

Thursday Afternoon Technical Discussion

Synopsis:  As we wind down from another beautiful day, expect some increasing clouds overnight with a chance for showers. Tomorrow will be beautiful yet again with mostly sunny skies, but high temperatures will remain well below normal. As we head into the weekend, a gradual warming will occur bringing temperatures back to normal, if not slightly above. For next week, temperatures will continue to hover around normal with some potential for cloudy and rainy conditions, especially in western Pennsylvania.

Short Term:  As the low pressure system swings north into Canada and its associated cold front moves off the coast, a strong area of high pressure will build over the mid-Atlantic.  This high will sit on top of PA bringing gorgeous weather to the area with high temperatures soaring into the 60's.

Long Term:  As next week begins, the high will move out of the area on Sunday night as a weak, slow-moving low pushes through the area.  This disturbance will induce building clouds and some scattered showers throughout Monday and Tuesday.

Michael DiDomizio

Thursday Morning Forecast

Synopsis:  We are starting off today with bright sun, clear skies, and cool temperatures. We can expect tomorrow to be similar today with temperatures starting to moderate a bit. As we head into next week it looks like the current pattern in going to hold steady. Skies should generally remain clear and temperatures will rise a few degrees each day as we head into next week. There are also no real storm threats over the next week, so just expect sun, dry weather, and comfortable temperatures as we head into finals week!

Short Term:  As the low pressure system swings north into Canada and its associated cold front moves off the coast, a strong area of high pressure will build over the mid-Atlantic.  This high will move in from the southwest and induce a southwesterly isallobaric wind, which will keep temperatures from dropping too much in the wake of the cold front.  The high will park itself right over PA for most of the weekend, keeping temps seasonal and skies partly clear.

Long Term:  The high will move out of the area on Sunday night as a weak, slow-moving low pushes through the area.  This disturbance will induce building clouds and some scattered showers throughout Monday and Tuesday.

Monday Night Technical Discussion

Synopsis

 

High pressure will continue to build over the state leading to a stronger southerly flow and warmer temperatures across the state. A low pressure system will pass north of PA on Wednesday and it's associated cold front will cross the state Wednesday afternoon bringing scattered rain showers and potential for storms across the region. High pressure will begin to build over the state behind the cold front for the end of the week resulting in clear skies for much of the state. As the high pressure begins to move off shore Saturday and Sunday a slight chance for scattered rain showers statewide will be present for the weekend.

 

Short Term (Monday night thru Wednesday Night)

 

A mean easterly flow off the Atlantic will provide a chance for increasing clouds overnight for the southern half of the state, thus keeping low temperatures near the mid 30's. Skies should remain clear for the northern counties allowing temperatures to drop into the upper 20's overnight. Clouds will stick around for the eastern and central portions of the state for the beginning of the day keeping temperatures in the mid to upper 50's but high temperatures could reach the upper 60's in western PA. Clouds will once again increase overnight keeping low temperatures in the 40's across the state. The 18Z GFS is a little quicker than the 18Z NAM, as the GFS has the precipitation reaching northwestern PA by 12Z, while the NAM has the bulk of the precipitation reaching the state by 15Z. This leads to a large difference in the high temperature as the GFS keeps most areas in the 60's, while the NAM gets central and eastern PA into the 70's. Given ensemble guidance, am currently favoring a mean of the solutions at the moment with some areas possibly reaching 70 on Wednesday. A chance for thunderstorm development looks unlikely, especially for western and central PA due to the clouds ahead of the precipitation cutting off the potential for convection and minimal CAPE. Low temperatures in the lower 30's will follow the passing of the cold front Wednesday night.

 

Long Term (Thursday into the weekend)

 

High pressure will begin to build over the state Thursday morning and continue to do so through Friday allowing temperatures to approach near normal values. There will be a chance for a scattered rain shower across northern portions of the state Thursday night due to a westerly flow off the lakes. As the high pressure begins to move east of the region Saturday afternoon and Sunday, the 18Z GFS has scattered rain showers across the state Saturday afternoon through Sunday, but confidence remains low. Otherwise, conditions look dry for the weekend. 

~Aaron Herbert