Ok , I’m still up. It’s 11:45 and the GFS has almost identical QPF as the NAM and a bit colder. It’s looking like at least12 inches in PHL and immediate surrounding suburbs north and west.
The latest NAM data has become available and it has reverted back to a somewhat warmer, but more intense storm.
Latest QPF value has increased to 1.30 inches water.
For the Philadelphia area and immediate suburbs, it shows about 6-8 inches by daybreak, BUT it shows that temperatures in the upper atmosphere warm up so that a several hour mix of sleet and freezing rain is possible in PHL and immediate suburbs, from 6 am to 9 am before a return to all snow, ending about 1-2 pm.
The GFS model data won’t be available tonight until after my bedtime 🙂
Still too early to try to pin down storm totals. I’ll be updating tomorrow, so check back.
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.)
Weather… and Other Things 'Up in the Air'
