Tonight’s NAM has a QPF of 0.14 inches water. There is a sharp drop off of precipitation in areas north of the turnpike (as an good approximate northern extent.). For tonight, 1-2 inches of snow in areas south of the turnpike, ending about 8 AM.
Areas further south of the city may have up to 3 inches and the snow will end later.
Light snow returns late in the afternoon Monday and increases in intensity late in the evening.
The second storm Monday night into Tuesday will be complex and I’ll be tackling that tomorrow. Stay tuned.
Still away on vacation 🌴, but I thought I’d chime in on the weather for Tuesday.
An upper air disturbance will move across the area on Tuesday. The latest NAM model has moved up the QPF to about 0.20 inches water. Upper air temperature profiles marginally support the precipitation falling as snow, BUT near surface air temperatures will likely be above freezing for much of the time. Additionally, ground temperatures have been above freezing for awhile.
As a result, a very wet snow is expected with very little accumulation — likely just a coating, more on grassy surfaces.
The 1 AM NAM model run has extended the duration of the light snow to about 10-11 AM. Expect possibly an additional 1/2 inch of snow after sunrise in PHL and immediate surrounding suburbs.
Temperatures are expected to drop below freezing, causing icy conditions.
Tonight’s NAM data just rolled in. QPF values are again very low in the immediate PHL area, about 0.09 inches water. With some of that falling before surface air temperatures fall to 32, it would appear that the best guess is a coating to 1 inch in PHL and the immediate suburbs.
Areas farther north and west may have 2, possibly 3 inches.
The biggest issue, regardless of accumulation, will be that any wet accumulations will become icy in the morning, with temperatures dropping below freezing for a time. Stay safe!
This afternoon’s GFS and NAM have maintained a low QPF of less than 0.10 inches water in the immediate PHL area and south. Under ideal conditions, we would have about an inch or so of snow. HOWEVER, the surface temperatures have been above freezing today and won’t drop below 32 until 4 AM. While the heaviest QPF is expected between 4 and 7 AM, the warm surface temps will likely cut into accumulations.
So…still going with about 1 inch of snow in the immediate PHL area an adjacent suburbs. Area north and west (Doylestown, Allentown) may have closer to 3 inches. Again, a difficult forecast, since warmer surface temperatures will be reducing accumulations.
Whatever falls, there is agreement that temperatures drop below freezing for the morning rush hour. So icy conditions will be an issue.
Tonight’s NAM data first becomes available about 9 PM or so. I’ll update then.