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.