Technical Forecast Discussion
Synopsis:
Scattered showers and thunderstorms will continue to affect our region. Large and vigorous low pressure systems situated over the lower Midwest will continue to provide the necessary instability for convective rain developments. The high pressure ridge located over the Atlantic Ocean will also continue to pump in moist air from the south. Expect scattered or isolated thunderstorms to develop later in the day on Tuesday and continue into Tuesday night, some of the storms could be on the strong side. Expect a similar weather pattern for Wednesday. However as the low pressure's cold front approaches, the showers and thunderstorms will gradually organize into lines late Wednesday night. The line of showers and thunderstorms should sweep through some time Thursday morning. Behind the cold front, the skies will gradually clear and temperatures will fall back to seasonal. Expect sunny skies on Friday and a nice weather to start the weekend.
Short-term (Tuesday – Wednesday):
The short-term synoptic setup favors the development of scattered showers and thunderstorms over the region, especially in the afternoon hours when day-time heating provides the atmosphere some extra instability. A vigorous low pressure system will continue to strengthen over the Midwest as a very strong jet-stream pushes eastward across the Rockies. Ahead of the storm system, high octane moist air will overspread the Midwest, Southeast, and Northeast. Combined with very strong jet-stream and high CAPE instability, severe thunderstorms will continue to develop across the Midwest on Tuesday just like past couple of days. Also expect some scattered showers and thunderstorms to develop here in the Northeast as day-time heating combined with high dewpoint temperatures, will create some instability in the atmosphere. We still can't rule out the possibility for severe thunderstorms as the CAPE will be marginal for supercell developments.
Looking elsewhere in the nation, the aforementioned low pressure system will spin northward into upper-Midwest. The 500-mb low will cut itself off from the main jet-stream. However, another area of PVA and jet-streak will cross the Rockies early Wednesday morning; these will generate another strong low pressure over lower-Midwest. Unlike the first low pressure system, this new storm system will slowly push towards the northeast. Its associated cold front will finally sweep the moisture eastward. Expect lines of showers and thunderstorms to slowly migrate eastward on Wednesday. However here in the Northeast, we are still going to see scattered showers and storms to develop later in the day on Wednesday.
Mid-term (Wednesday night – Thursday night):
The lines of showers and thunderstorms will finally approach the state late Wednesday night as the cold front nears. The timing of this frontal passage differs among the model guidance. The GFS, ETA, and RSM are all on the faster side of the spread, suggesting the cold front should sweep through the western and central portions of the state sometime early Thursday morning. On the other hand, the WRF is delays the progression of the jet-streak crossing the Rockies, thus suggesting the lines of storms should pass later in the day on Thursday. If the front shall pass the central portions early in the day, only expect the possibly of some strong thunderstorms for eastern PA as day-time heating initiates. However if the storms shall pass later in the day as the WRF suggests, central and eastern PA may see some strong storms in the afternoon. The skies should gradually clear out Thursday night across the state after the front passes through.
Long-term (Friday – Saturday):
After the front sweeps through, some much needed drier air will finally filter into the region. The temperatures will fall back down to seasonal. However, the winds will also quiet strong behind the storm system. Expect partly cloudy skies and breeze conditions on Friday. As the storm system pulls away, the winds will gradually die down. Overall, it looks like we will have a nice start to the weekend.
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