Snowfall Discussion, Saturday's Winter Event
Winter Storm Warnings and Winter Weather Advisories
Warnings: Poconos
Advisories: North and West of Philadelphia
Warnings: Poconos
Advisories: North and West of Philadelphia
After cautiously getting my hopes up for Philadelphia's snow starved to receive a decent snow event on Saturday we're back to another one of the same old, same old routines. While temperatures will be nice and chilly to start the event in Philadelphia, low pressure is going to track really close to the city as it moves from west to east across the Mid Atlantic. Today's midday computer guidance has inched the storm a bit to the north and closer to us. If these forecasts are right they will have brought warm enough air into the picture as far north as the Philadelphia suburbs to lead to a potential mix and/or changeover to rain. The drawback of such a close track, of course, is that a slight deviation south is going to shift snowfall totals a nudge south and a slight shift north nudges the rain/snow line farther north. In other words, this and most forecasts you see could very well bust badly in a twenty mile range near Philadelphia.
This is a two pronged event, with the first wave being some overrunning snowfall during the morning hours before a lull in the activity before the second wave of precipitation works in during the afternoon. The first wave should be mostly snow although this first wave will likely be from the city on north. The problem is with the second wave, which will be accompanied by low pressure as it tracks eastward. The more northward nudging in the GFS and NAM in the midday run was accompanied by a southward nudge in the EURO, which pretty much all tend to shove the low pressure center across our region whether it be just north or just south of the city.The good news? Philadelphia will get at least SOME snow from this system although the totals will not be that much, with modest accumulations expected across the city ranging from around an inch down by the Airport to 1-3" in Northeast Philly. However, milder air will work in and turn the precipitation to rain or a mixed bag of slop and snow for a time during the latter half of the event on Saturday evening.
The best chances for an all snow event are across the Lehigh Valley, Central Pennsylvania, and the Poconos and several inches of snow will be expected across those areas. Across the far northern and western suburbs (Upper Bucks and Montco) and Central Jersey, mixing may occur late in the second half of the precipitation. If you don't mix with sleet or freezing rain, you could see all snow and get slightly higher totals than what you will see forecast here.The northern suburbs (the PA Turnpike and I-195 corridor) and the northern half of Philly will see more mixing and less of an all snow event. Again, like with Upper Bucks and Montco, no mixing equals more snow.
South Philly, Lower Delco, Wilmington, and South Jersey will probably change over to rain at some point but should see some snow at the onset of the activity to help them get a coating of snow or around an inch of snow before the lull and then the rain that will move in later on.
How much, specifically? Check the map and the graphic below to see your totals.
This system will move out late Saturday night and help reinforce cold air for early in the week, with temperatures in the 30's continuing through Tuesday before the Siberian Surge comes late next week.
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