High pressure will move off to our east on Saturday.   Sunny skies and very mild temperatures for Saturday, with highs near 60 as the jet stream retreats well north of our area.

Some mid level cloudiness moves in late Saturday afternoon as a weak front moves through Saturday evening. There’s a chance of a brief sprinkle.  Strictly speaking, it’s a cold front, but temperatures will actually be higher on Sunday due to the fact that the air mass moving in is a continental airmass instead of an airmass from Canada.

Sunday will be mostly sunny and unseasonably mild.  High temperatures in the low 60s.

A warm front moves over the area and stalls just to our north on Saturday, giving us cloudy skies and milder temperatures . High about 49. (Average high is 42 for this time of year.)

The warm front hangs to our north on Sunday because the jet stream flattens and runs parallel to the front.  A wave of low pressure develops on the stalled front and moves east over Pennsylvania, giving us clouds and rain on Sunday. An easterly flow will keep temps cooler on Sunday, with a high of 45.

The low intensifies rapidly off the New England coast on Monday giving us very windy conditions.

The big focus of this impending snow has been on the QPF and the duration of the precipitation.

One thing that seems to have escaped higher scrutiny are the warm temperatures.  Looking at the current short range GFS LAMPS forecast, it has surface temperatures well above freezing past the peak precipitation time.

While the current models show the upper atmosphere cooling down to support snow by about 4-5 AM the big unanswered question, will it be cold enough for the snow to accumulate to the levels being forecast?

Reviewing the current short range MOS and LAMPS, I’m beginning to think that the temperatures may not drop soon enough for as much accumulation to occur as being forecast.

So what is being forecast as a major snowstorm of 6-8 inches may actually only accumulate 3-4 inches if the cold surface temperatures arrive too late in the morning.   (In that case, ice under the snow. will be a bigger issue with this storm.)

I wanted to share this concern that the current forecast may not be correct.  Indeed, that’s why many of you read this blog. 

The next NAM data will be available within the hour.  I’ll update then.