WED NIGHT

SYNOPSIS: Exiting upper level high tonight will give way to a wave of low pressure. This will set up an elongated area of precipitation tomorrow. A small high pressure system will takes its place on friday bringing tranquil conditions. After some showers pass through this weekend, next week's weather will be dictated by a large upper level ridge. 

 

SHORT TERM: Clouds will increase overnight due to an approaching low pressure system that will move to our south overnight. Widespread showers can be expected for most of the day on Thursday. This system will depart overnight Thursday and amplify over the atlantic ocean. However, the commonwealth will see clearing skies and the return of tranquil condtions on Friday, due to the presence of a weak surface high pressure system. Temperatures on Friday will be much below normal and it will feel even cooler with breezy conditions.

 

LONG TERM: Another storm system will pass to our south this weekend, bringin showers late on saturday. A large upper level ridge will approach the region next week. This will provide an extended period of warming temperatures and tranquil conditions through at least the middle of the work week.

Synopsis:

High pressure will slide off the east coast later tonight, giving way to an area of low pressure which will move through the Mason-Dixon Line during the day tomorrow and spread precipitation throughout the state. A Canadian high pressure will then settle in for Friday into the upcoming weekend, however, another disturbance may slide to our south later Saturday bringing the threat of rain and even snow to the higher elevations. Temperatures will be several degrees below normal before a warm up occurs later next week.

Short Term (Tonight through Thursday Night):

Skies will be mostly clear through the early evening before clouds increase during the overnight ahead of the approaching low. Rain will begin to spread into the western zones during the daybreak hours and into the eastern zones in the late morning. Amounts will generally be between 0.25 to 0.50 inches. All of the rain will end by the evening. The winds will increase later Thursday night as a tight pressure gradient sets up due to the departing low and the arriving high pressure from Canada.

Long Term (Saturday and Sunday):

Canadian High pressure will dominate throughout for the upcoming weekend. With that, temperatures will be several degrees below normal as the flow will be out of the north. A disturbance may slide to our south later Saturday night bringing the threat of rain and possibly snow in the higher elevations. Confidence, however, is low at this time as there is significant spread with the models. Both the NAM and GFS bring some precipitation into the state, while the ECMWF keeps the precipitation suppressed to the south.

Tech Disco 4-23

Synopsis

After some moderate wet snowfall this morning, this week will be mainly damp and cool with a little spike of warmth late, but with a dominant trough aloft, clouds, wind, and showers will dictate the atmosphere for the upcoming week with no signs of change from this within the near future.

Short Term

A large trough at 500mb extending down into the Carolinas will be slow to exit as a weak longwave system works to push the trough off the coast. While this trough lingers, low pressure sitting off to our northeast will casually revolve around itself while deepening the surrounding pressure gradient from continuous PVA. From this low, the western counties will experience on and off rain showers with more snow mixed in at night and in the northern sectors with higher elevations. Thick, dense clouds will remain in place through Tuesday night, and with the low's positioning overnight tonight and Tuesday, moisture draw from the Great Lakes will assist in developing scattered precipitation  in the western counties tonight and throughout Tuesday afternoon. This low will begin to progress northward starting Tuesday night, allowing for a small surface ridge to clear the low and its associated clouds briefly Wednesday afternoon.

Long term

Wednesday afternoon, the massive trough will exit the region and will allow for small ridge in the longwave system to bring some clear conditions for the late afternoon throughout the evening. Thursday, a low pressure system will approach, allowing for WAA ahead of its cold front to warm the state to the near 70s regime before the front crosses sometime during the afternoon. This low will track to our north, and from a NAM perspective, the state will sit in the weakest part of the trough, bringing minmal rain to the state while the front passes on. The GFS, however, maintains the structure of the gradient and scatters precipitation throughout the state.  Strong dry flow behing this system along with a sharp ridge will move in Friday, bringing cold Canadian air into the Northeast to kick off the weekend.    

Wednesday Night

Synopsis: 

An upper level trough will bring scattered rain showers to the southeastern portions of the commonwealth overnight. A high pressure system will move in tomorrow bringing fair and calm conditions through Friday. A storm system will ride up the East Coast over the weekend. The upper level system will move onto the East Coast on Sunday and impact the region for extended period of time. Unsettled weather is slated to be in the forecast into early next week. 

Short-Term:

A weak shortwave is moving through northern Virginia. Ahead of the system are some scattered showers which will impact the southern portions of Pennsylvania. This shortwave will exit off the coast overnight. Behind this weak system a high pressure will build into place. Moist conditions and clear skies will produce patchy frost in the northern mountains along with fog (especially in the valleys). Calmer and clear conditions will be present with the high pressure system which will stay in place through Friday. 

Long-Term: 

High pressure will eventually slide off the coast overnight Friday and during the day Saturday. An upper-level ridge will build into the western Atlantic. This will create a set-up for unsettled weather for several days. A low pressure system will ride up the east coast Saturday and bring lots of rain to the Eastern U.S. The upper-level trough associated system will move onto land and become cut-off. Rainy and unsettled weather will follow well into next week. 

Dakota Smith

Wed. PM: Warm then Wet

Synopsis:

An area of high pressure is heading northeast and a weak warm front will head north through portions of the western and central Great Lakes over the next day or two. To start, temperatures for the rest of the week will head back into the 70s by Friday as an upper level trough and surface cold front approach the area on Friday, influencing the weather for Blue and White Weekend and early next week.

Models Used: 12Z NAM, GFS, ECMWF, & CMC; MOS & Teleconnections also used

Short-term:

Friday will be the peak heating of the weekend as the cold front is right on our doorstep but moving very slowly. 850 mb Temps will be between 8 and 12 degrees Celsius.

Long-range:

Nor'easter could arrive for Monday/ Tuesday (mostly rain) as a long-wave 500 mb trough splits over the Plains, the southern branch then forms a cut-off low, which phases just to our north on Monday. Models are in general agreement with this scenario.

Thicknesses will be too high for snow but the NAO is heading for neutral. When the upper-level CLOSED low heads our way, the thicknesses will be around 534 Dm and the 850 mb temp. will be around -5 to 0 degrees Celsius next week, so wet snow in the higher elevations cannot be ruled out.

-Jaron Breen

Tech Disco 4-16

Synopsis

The record breaking heat that has draped itself across the state is on its way out, and the state will be dropping back into an average temperature regime, with warm advection late in the week  serving as the odd days in the forecast/ otherwise, the daily progression of theweek's weather is like a roller coaster: we start stormy, cool, dry, and clear for the next day, then clouds with storms possible, followed by calmer weather. The weekend outlook will be intriguing, with several different scenarios leaving the possibility for a winter whiteout in the East.

Short term (Monday Night thru Tuesday)

The heat will remain in place for tonight, allowing for convection and synoptic lift along the cold front to bring the potential for thunderstorms within the western and central thirds of the state, with decreasing probabilities from west to east. Although the GFS and NAM back down on activity, the 15z SREF has a 70% POP for western PA around 0z to 3z tonight. After this, high pressure builds in from the northwest to bring drier conditions to the state while CAA from the front cools the state down into the 60s. Although the front is presents, the mean flow behind the front currently remains southwesterly, and temperatures behind the front are about 5 to 8 degrees cooler, not very significant. Tuesday will remain dry with a NW wind allowing for gravity eave cloud formation, hinting at scattered cloud cover for Tuesday afternoon, with a potential convective shower.  CAPE values remain low, and high pressure is contributing to reduced winds along the surface and within the mixed layer.  

Long Term (Wednesday to the weekend)

Wednesday will be interesting due to model disagreement on a shortwave progressing across the Tennessee valley. The NAM indicates an undeveloped shortwave that helps the precip it generates remain in the Carolinas, but the GFS has a develop shortwant that drag rain along the MD border, giving southern areas the potential for clouds and showers in the afternoon. The SREf's leave no chance for rain within the entire state, leaving conern for a dry presence all day Wednesday.  For Thursday, a cold front stemming from a low dragging across Canada will bring clouds during the day with continued WAA under the clouds, allowing for a rather warm but muggy Thursday, and the WAA persists into Friday with a defined warm front heating the state into the 70s and 80s like today, and pushing rain showers along a cold front that is projected to hit overnight Friday into Saturday.

**Note: keep an eye on the forecast for next Monday (4-23), the Euro and CMC hint at a Spring snowstorm for the East, mainly along the Appalachians.**

Sun. PM: Warm & Stormy and then cooler

Synopsis:

Mid-latitude cyclone to bring nasty storms to PA Monday evening into Tuesday AM. High pressure rapidly builds in behind it for the middle of the week. Dry but cooler. Weak system to bring scattered showers to PA on Thursday.

Models used: 12Z NAM & GFS; MOS

Short-term:

The system that brought the severe weather is sliding eastward. Look for sunny skies during the day with temps in the upper 70s -> mid-80s and dew points well into the 60s to provide enough destabilization. Surface-to-1-km SR Helicity values of 150-200+ m^2 per s^2 should provide enough shear to allow multicellular storm clusters and a squall line to develop and trek across western PA. (We need shear to be at least 75% greater for supercells to form.) After hitting the Appalachians, the storms should weaken not only because of the effects of the mountains but also because they will arrive in central PA around midnight with instability decreasing. Heavy rain and gusty winds should spread into central PA and heavy storms will also affect eastern PA overnight.

Long-range:

High pressure will be on the cold front's heels, influencing our weather for Tuesday. Frost is possible north of I-80 and west of I-81 as lows that night reach the mid 30s.

A weak low is forecast to slide by during the later part of the week, bringing showers.

-Jaron Breen

Hope everyone lived through the storms in the Plains states last night and yesterday afternoon. We wish a speedy recovery to all those in the affected areas.

WED NIGHT

Synopsis: A slow moving upper level low pressure system that brought cold weather, breezy conditions, and even a bit of sleet and graupel will continue to move out of the picture on Thursday. In its wake, high pressure will take control for the first half of the weekend with the next chance of wet weather coming by Sunday.

 

Short Term: Showers and wintry weather will come to an end overnight tonight, as the slow upper level low spins its way out of the picture. Skies will clear as the day progresses on Thursday, as an area of high pressure builds into the region for Friday and Saturday. This will bring with it a slight moderation in temperatures along with dry and tranquil conditions.

 

Long Term: Model guidence and ensemble means tend to congerve on an area of prolonged rain setting up late this weekend into early next week. A warm front will pass through the region late on saturday, allowing for a warm and windy day for Sunday. This warm front will become stagnent early next week, setting up the chance of a prolonged period of rainfall, along with a cool down.

Synopsis: The upper-level low that has provided for below-normal temperatures and rain/snow showers across the region will slowly move off towards the east later tonight into Thursday. A large dome of high pressure will settle into the northeast later Thursday night into Friday and provide for fair weather and moderating temperatures. A warm front will move through the state on Saturday producing clouds and some showers. Then as heights rise over the east coast in response to the building southeast ridge later this weekend and into early next week, very warm temperatures will accompany.

Short term (Tonight through Friday):

An upper-level low that is currently over most of the northeast is producing scattered rain/snow showers throughout the region, however, as the upper-level low moves off the east coast later tonight and into Thursday, the showers will diminish. Thursday will see an improvement from today's weather as clouds should break for some sun and temperatures will be about 8-10 degrees warmer. As high pressure settles over the region later tomorrow evening, skies will clear and overnight temperatures will drop to near freezing through most of the state. Friday will turn out to be a nice day with temperatures topping out into the 60s with abundant sunshine as the region will still be under the influence of high pressure.

Long Term (Saturday and Sunday):

A warm front will move through the state later on Saturday, producing some showers, especially along the northern zones. Then as heights rise on Sunday in response to the building southeast ridge, temperatures will warm up into the 70s across most of the state.

Tuesday Midday

Synopsis:  A trough digs through the region for the 1^st 3 days, then we clear out for Friday in time for another shortwave to impact the region on Saturday.

Short-term:  Spotty showers across the state today as the trough to the north start to dig into the region. Put in the possibility for snow in NC with temperatures just above freezing, did not follow MOS on this because of increase cloud cover preventing temperatures from going as low as MOS wants them to go.  The best chance for showers looks to be on Wednesday as the trough digs in and provides scattered showers during the day.

Long-term:  The trough moves out on Thursday, we begin to clear out.  Friday looks to be the best of the 5 days as high pressure takes command, but quickly moves out to sea as another short wave pushes into the region for Saturday, bringing the chance of scattered showers to the region during the day.

Kept temperatures near previous shift, with minor changes.

Sun. PM: A Tale of Two Patterns

Synopsis:

We are between low pressure over Maine and high pressure over Missouri, creating windy conditions until the end of the work week. For tomorrow through Thursday, a series of upper-level disturbances will touch off a few showers (sometimes wintry late-night). On Thursday and Friday, the wind will die down and temperatures will begin to recover as the high heads east throughout the week.

Models Used: 12Z NAM & GFS (watch out for their fast tendencies); MOS is ok, but adjust values a few degrees downward.

Short-term - Windy, Cool and Unsettled:

Advection of upper-level vorticity maxima will be the cause of the wet pattern. The jet stream's trough axis goes through PA and 1000-500-mb thicknesses are well below 540 Dm. Forecast soundings (thickness lines and isotherms will not work) indicate that the freezing altitude at night will be 900 mb (over State College), the surface temperature only 3°C, & Relative humidity will be close to 100% from 625 mb to the surface. The snow should change back to rain after sunrise.

Long-range - Transition to Warmer and Drier:

The jet stream will retreat northward and thicknesses will begin to recover as high pressure builds in from the eastern Plains late-week. The sun will return Thursday late-PM and clear skies appear to dominate through the weekend. The jet stream's ridge axis will be over PA on Saturday; the 540-Dm thickness line will be in southern Canada again. Temperatures should return to the 60s on Friday.

- Jaron Breen

WED NIGHT

Synopsis: High pressure will settle in and last until at least early next week. Dry and tranquil conditions are expected for the entire forecast period.

Short Term: Sub-freeezing temperatures are expected over night tonight, especially in the upper elevations of the western zones. High pressure will move in and provide an excellent spring day on Thursday and Friday with seasonable temperatures.

Long Term: Due to an approaching upper level ridge, development of a southwest flow, and the lingering of a high pressure system, warm and dry conditions are expected for the weekend. A ridge will drop into the region late sunday, passing a cold front through. This will be the next chance at precipitation and a cool down.

Wed. PM: Quiet & Comfortable

Synopsis:

A weak cold front is bringing a few showers to New England and a westerly flow aloft is bringing storms to the Carolinas from the same upper-level low that brought the severe weather and destructive tornadoes to parts of Texas yesterday. Today and tonight, the Commonwealth will be spared from any wet weather thanks to a ridge of high pressure centered in north-central Canada (yes, I said Canada). This high will slid south and east, controlling our weather for the rest of the week into the weekend.

Models used: 15Z SREFs, 12Z NAM & GFS

Short-term:

The ridge in Canada is unusually large, large enough to influence our weather from afar. There's also a vorticity minima stretching from International Falls, MNto the Atlantic Ocean east of New Jersey. Under clear skies and diminishing winds, the temperature should drop substantially overnight with more days of frost for those that make it into the 30s.

Long-range:

The high slides south then east and temperatures start to climb this weekend as a result of changing flow patterns and advection.

-Jaron Breen

P.S. We all hope that those folks in northeast Texas survived the destructive tornadoes that hit yesterday.

Tuesday Midday

Synopsis:  High pressure today before it moves out tonight as a cold front pushes through tonight (back-door).  A trough tries to dig into New England, ridge of high pressure builds in for the end of the week.

Short-term:  Clear conditions will last for most of Tuesday, all the models are in agreement.  Clouds will start to increase Tuesday night in advance of a frontal system, nothing should really spark from this front, still put a chance for scattered showers overnight and early Wednesday morning.  Western PA stands to see a better chance of a shower Wednesday Morning then the rest of the state.  Wednesday morning the state should clear out, it will be breezy with winds from the N/NW but partly sunny rest of the day.

Long-term:  A trough will try to dig into Northern New England, this combined with the passing of the front will keep Thursday as the coolest day of the 5 days.  But a ridge of high pressure will try to push this trough to the east as we progress into the Easter Weekend.  High pressure dominates/builds as we push into the Easter Weekend.  Next shot for rain will be late Easter Sunday, early Easter Monday.

Kept temperatures near previous shift, with minor changes.

Sun. PM

I used the 12Z GFS and NAM Models on AccuWx Pro and NWS MOS Tables. Frost possible Monday night. The general discussion pretty much says what will happen this week fairly well:

General Discussion: A weak cold front will move across the Commonwealth this evening. Look for cloudy skies and a passing shower through at least midnight. High pressure will build in during the wee hours tonight and bring sunny skies through Tuesday evening. A weak cold front will bring mainly clouds overnight Tuesday into the wee hours Thursday. A few showers falling on Wednesday and Thursday cannot be ruled out. High pressure sets up over the Eastern Great Lakes while a weak disturbance passes to the south during the second half of the work week. Partial sunshine and dry conditions will prevail from Thursday onward. High temperatures will be in the 50s and 60s this week while lows vary in the upper 20s to the north and mid-40s to the south. This week's trend is a steady increase in temperatures each day despite the passing systems. Have a great week!

-Jaron Breen