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