Sunday 6PM Update: This afternoon’s NAM and GFS model runs continue with a significant snowstorm for us starting after 1 AM Tuesday and continuing through at least late morning on Tuesday. Total QPF is about 0.80 (NAM) and about 1.00 inch (GFS) for Philadelphia. With a 12:1 ratio, we’re talking about 9-12 inches of snow as a current estimate. It’s expected to be very windy as well. Updates about 10:30 tonight.
Just a quick update:
The NAM has joined the GFS with a slightly more eastern track for the storm, putting us in the cold sector. The storm looks like it will be a faster mover and not linger into Tuesday afternoon.
Current QPF values are about 0.75 inches water for the NAM and about 1.00 inches water for the GFS. With a 12:1 ratio, we’re taking at least 8-10 inches for PHL, mostly occurring before daybreak and very early morning Tuesday. Effects of the March sun through the clouds won’t be a factor for much of the precipitation, but will allow for faster melting on roadways once the snow ends. Temperatures remain below freezing.
The details really can’t be nailed down until Monday evening. I’ll update later tonight. (The updates will be after 10:30 PM and will only be for the NAM, with the GFS data coming out an hour later.)