The potential for a significant snowfall over 5" is improving for Wednesday. Model guidance continues to bring over an inch of liquid equivalent to most of New England. The NAM has become more robust with developing secondary low pressure south of Long Island and moving it northward over southeastern New England. This would allow colder air to be entrenched in the region longer, and as a result, greater snowfall totals. However, the strong secondary low is not a model consensus and there are definitely details to be ironed out.
Temperatures will be fairly isothermal up through 700mb starting as early as Tuesday evening as warm air advection intensifies aloft. However, the column should remain below freezing through the morning hours. This is when the bulk of the precipitation will fall anyway, so the majority of liquid equivalent should fall as snow or sleet.
The next question is the quality of snow growth. The snow growth region will be between 600mb to 450mb in the morning, shrinking to 550mb to 450mb by the early afternoon. The best omega comes right around 14z to 15z between 500mb and 400mb and continues at moderate strength through 18z, before it shuts off for the most part. We should get a decent thump of snow between 14z and 17z. By 18z, count on a change to sleet, maybe some freezing rain, and light rain later in the evening. Showery precipitation may continue behind the storm through Wednesday night, and should change to snow as cold air advection work in after midnight.
Current thoughts on total snow and sleet accumulations in Keene: 4" to 7"
--- Snowday Outlook ---
First real threat of the season is coming up Wednesday. Snow should start to fall by 6am Wednesday morning, and fall heavily between 9am and noon, accumulating to between 4" and 7". By 11am, precipitation will begin to mix and change to sleet and freezing rain, and by 1pm, plain rain. I think the moderate snow accumulations in the morning plus ice potential may be enough for a cancellation, however I'd like to be more confident on higher snow accumulations, and a slightly earlier start time.
2 comments:
Dear Sam,
We miss you here at Keene High, but you are still quite famous and everyone has been checking your website. I was thinking: if you ever wrote a book you would already have a fan base of about 1600 people.
I hope college is going well. Happy Holidays!
Molly Bulger
Sam,
you are still the man. thanks for the great info and predictions. keep us in the loop. what college?
-Dr. J
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