Nice discussion from Mount Holly. Mention of blizzard conditions for coastal DE.
Spectacular satellite imagery over the East this morning as a strong area of low pressure comes together to our southwest. Just a classic eastern US winter storm presentation. A blossoming shield of precipitation is now overspreading the local area. A major winter storm will affect southern portions of the area over the next 18 hours. The main change to the forecast overnight was an increase in QPF, and by association, snowfall, for areas previously within and that were just north of the previous Winter Storm Warning. The QPF increase is almost unanimously supported by the last two cycles of global and hi res guidance, and translates to an increase in snow totals. The most difficult portion of the forecast remains the northward extent of precipitation shield. Even many of the recent model runs which increased QPF across the south generally didn`t move the precipitation shield north much. The latest blend does bring amounts up somewhat in the I-95 corridor. However, there is likely to be an exceptionally sharp northern cutoff to accumulating snow, probably even sharper than the latest forecast, which as it is has a much sharper than normal gradient. Even across, for example, Philadelphia County, it would not be surprising to see a significant difference in totals. And for northern portions of the area, it will simply be a cloudy and cold day with perhaps some flurries. Confidence in snowfall is much greater for southern areas. It is clear now that a swath of heavy precipitation will overspread the region. Extreme frontogenetic forcing is allowing precipitation to expand in coverage and intensity to our southwest, and this will only continue today. While precipitation is beginning as rain in some places, temperatures are continuing to cool behind yesterday`s front, and a flip to snow will occur. One possible exception is far southeast Delaware, where rain or mix could hold on for longer. Amounts were reduced a bit there. Otherwise, a large stripe of 8 to 12 inches of snow is now forecast, and can`t rule out some localized amounts a little over 12 inches. Snowfall to our southwest has generally been over-performing, and this trend could continue into our area. Snowfall rates could easily exceed 1 inch per hour at times this morning, perhaps 2 inches per hour. While snow ratios overall will be less than 10:1, these rates will quickly overwhelm the warm ground conditions left by recent near record warmth. These snowfall rates could persist for several hours this morning and early afternoon. Banding features are certainly possible within the heavy snow shield, leading to some local variations. Eventually, precipitation will end from west to east late this afternoon and this evening as the area of low pressure moves out to sea. Northeast winds will become strong near the coast today, gusting in the 30 to 40 mph range for several hours. With heavy snow occurring through this period, a period of near blizzard conditions is possible for areas such as Sussex County DE and portions of Cape May and Atlantic Counties. A Blizzard Warning was contemplated, but am not confident enough in criteria being met for more than brief periods.
