We went from 50s yesterday to seasonal temperatures today and a light to moderate winter storm that has its eyes set on the forecast area for late tonight through early afternoon tomorrow, most of the wintry weather will be focused well north and west of the I95 corridor
A cold front that came through last night has stalled just to the south of NJ as it hit the southeast ridge with an area of low pressure forming along it, this low pressure will ride the front along the NJ coastal waters, just west of the benchmark and will travel east-northeast from there
This storm track will initially cause an easterly wind off of the above normal Atlantic ocean which will once again mean coastal areas will be all rain , however to the west of I95 where cold air is entrenched this will turn out to be a wintry mess for the morning commute, areas along and just west of I95 will be in the battle zone
The models still differ a little but the latest observations point to the colder NAM model guidance being more correct
We see as of right now the snow line (the 0C line at 850 mb) would currently be over NW NJ
We see the latest NAM initialized right where it is , the GFS has been initlizing over NE PA about 50 miles NW , while it doesnt seem to be much of a difference, but its crucial to who gets what
Whats expected to happen is as heavy precipitation comes in it will cool the upper atmosphere and bring that snow line south to Central NJ for a time before retreating back north to just about where it is now as the low approaches an brigs in warmer air aloft again
When precipitation moves in the snow line comes south
The heavy preciitation p late tonight brings it even further south with NYC (especialy west) and central NJ getting in on a heavy burst of snow and sleet
Then it starts to slowly go back north as warm air comes in aloft BUT cold air remains at the surface, for areas like Union , Hunterian and Somerset counties , this would be sleet and freezing rain and quite an icing after the snow with surface temps around or below 32 and 850 mb temperatures above freezing , im a bit skeptical of this with lack of high pressure to our north but its something to watch for , im thinking the icing is a bit further north in the mountains and higher elevations.
Anyway after that warmer air begins to win out and most of the area slowly turns over to all rain besides extreme NW NJ and NE PA where snow turns to light sleet and freezing rain at the end of the storm
My final call
Green – Heavy rain , some sleet may mix in , 1/2 -1 inch of rain , locally higher amounts
Pink – Start as rain , transition to rain , snow , sleet mix than back to soaking rain , Trace south up to 1 inch of snow and sleet north
Light Blue – Start as rain or rain/sleet mix go over to mainly snow (could be heavy) then over the sleet and freezing rain, finally changing to all rain general slushy 1-2 inches of snow and sleet with a coating of ice (0.05 south – 0.10 north) , locally up to 3 inches of snow north .
Dark Blue – Snow to snow sleet mix, some freezing rain south 2-4 inches with up to 0.10-0.15 of ice south , 3-5 inches of snow north locally 6 inches possible
I expect precipitation to move from SW to NE overspreading the area between 9 pm south to midnight north ending tomorrow between 11am and 2 pm as mainly rain for mostly everyone.