Weekend Snow!

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Another snow event is on the way and it looks like this one will deliver! At this point I’m expecting 4″-8″ of snow with the possibility of a bit less at the coast. For 48 hours out this is a fairly high confidence forecast.

This storm isn’t going to be particularly intense as the polar and subtropical jet streams never really phase. It’s when the 2 jet stream branches come together that you really get fun weather! Nonetheless, a juicy (lots of moisture) disturbance in the southern branch of the jet streak will fly toward us while a cold, Canadian high pressure remains anchored over southern Quebec.

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Because the storm never really phases and the mid level low (between 5,000 and 10,000 feet or so) never really gets going until the system gets into the Gulf of Maine the upward limit for these kinds of events for Connecticut is generally about 10″.

I expect some light snow during the day Saturday that may put down a fluffy inch or two in some towns. The atmosphere will be saturated and quite cold! Cold enough that there’s actually favorable dendritic growth during the day Saturday. By Saturday night we get plenty of lift thanks to strong isentropic lift/warm advection. It peaks right around midnight when we should really be ripping snow for at least an hour or two.

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While snow growth during the day Saturday looks good the signal is much more muted Saturday night as milder air races in and the best lift is centered in the lower part of the atmosphere. I’m thinking a 15:1 or even 20:1 snow/liquid ratio during the day Saturday followed by 10:1 Saturday night. Depending on the surface low track a change to rain is possible along the shoreline and a mix with and change to sleet pellets before the snow winds down is possible all the way to the Massachusetts border (especially northeastern Connecticut).

A few things about these “front end thumps” of snow. They tend to come in faster than forecast and also leave earlier than forecast. If that turns out to be the case this time most of the meaningful snow should be out of here by daybreak Sunday. A relatively low impact event since the heaviest will fall on a Saturday night.

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