What has started as a cool and active week will continue being so as we have a powerful negative NAO block in the northern Atlantic, you can see a trough dominating the NE US , some changes are on the way for this weekend as the ridge in the west comes east but this trough will be sticking around through Saturday
Theres an upper level low circulating and stalled to the east of Maine off of the NE US coast , which is causing upper level disturbances to circulate through our area from the north and northwest leading to constant chace of showers and storms, this will be the case from tomorrow through Friday with a chance of showers and storms every day, especially in the afternoon.
So the next 3 days will be relatively uniform with partly sunny to mostly cloudy skies, a chance of scattered showers and storms everyday, best chance in the afternoon and early evening with the peak of daytime heating mixing with cold air aloft causing the most instability of the day. Storms may contain small hail with such cold air aloft
Highs will remain below average through Saturday , but will moderate a tad every day
Wednesday and Thursday highs will be in the mid to upper 60s for most of the area, around 70 in the Philadelphia metro, and Thursday more widespread upper 60s to low 70s as our trough begins to exit to the east, with again the chance of showers and storms
Friday we really start to moderate as the block starts breaking down and the ridge to our west begins to fill in , highs will range from the low 70s interior to the mid to upper 7os at the coast, the final disturbance will come through with scattered showers and storms in the afternoon
This weekend will be very nice and relatively seasonable to slightly above
Images off Penn State EWALL
On Saturday (above) , our trough responsible for all the cool and rainy weather exits east and ridging from the west builds east, which means rising heights over the east, so clearing skies along with warmer conditions with highs in the upper 70s interior to low to mid 80s for the rest of the area.
Sunday a trough will really begin to drop south and that will really raise heights along the east coast and ridging will really build in with sunny skies and highs in the low 80s interior to mid to upper 80s elsewhere
This ridge will remain in control through early next week where temperatures will remain warm in the mid to upper 80s to low 90s through Tuesday before a cold front comes through Wednesday and flattens the ridge out. The flow will become more SW by Tuesday so there will be a gradient along the coast where highs may only top in the 70s from Cape May NJ through the southern shore of Long Island.
By midweek a new trough will build into the east leading to dropping temperatures to or slightly below average. The cold front on Tuesday will be our next shot at severe thunderstorms