April 4th, 2008 Forecast
Now: Skies are cloudy across the region with temperatures in the low 50's, with upper 40's along the coastline with winds coming off of the ocean. Temperatures will move little for the next few hours until rain moves in later this evening.Tonight: Rain will spread in from southwest to northeast, moving into Philadelphia later this evening. Temperatures will drop at the onset of the rain to the low 40's in Philadelphia and then hold throughout the remainder of the evening. Rainfall will be steadiest initially along and south of the PA Turnpike and I-195 corridor tonight, with rain becoming steadier later in the evening farther north. It is possible that some sleet pellets fall with the rain north of the city tonight at the start of the event as the lower atmosphere cools from evaporative cooling, with a period of snow and rain mixed possible across the Poconos' highest elevations before becoming all rain.
Temperatures will slowly climb on Friday with rainfall continuing through the morning, tapering to showers during the PM as the first low pressure center associated with this storm system moves to our northwest. Temperatures will reach their highest point during the early evening hours across Philadelphia and points northwest, with temperatures in the mid 50's in Allentown to 60 in Philadelphia.Round #2 of the precipitation comes through on Friday night and early Saturday with a wave of low pressure developing along the cold front. This wave of low pressure will ride northeast and bring a round of moderate rainfall to Philadelphia late Friday night through at least midday Saturday.
Computer guidance is suggesting significant rainfall for the region, with the NAM suggesting over four inches of rain for parts of South Jersey. While the computer models may be overplaying the amount of rain that is forecast to fall through Saturday night, the potential for one to two inches of rain south of I-78 across Southeast Pennsylvania and Central and Southern New Jersey is certainly real. Some areas could see more rain than that with the upcoming storm system.
Round #2 should end Saturday afternoon and we might see some sunshine before the end of the day. Some model guidance (among them, the EURO) is suggesting more rainfall south and east of I-95 for Saturday night and Sunday morning before skies clear. We should squeak out a pretty nice afternoon Sunday before an onshore flow develops, possibly as soon as Monday, as high pressure strengthens over Canada, pushing a northeast wind regime down the coast and keeping temperatures across the Mid Atlantic cooler than initially thought. Right now, computer guidance is holding the onshore flow and cool-air damming in place until Wednesday before we see things warm up Thursday. This is subject to change but as of now computer guidance is in pretty good agreement about as not being as warm as it looked earlier.
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