Winter Storm Update – 12/2 Sunrise Edition

Our forecast for this storm continues to hold steady, so that when all is said and done… the snowfall forecast remains the same.  You can find the storm detailed forecast here:  FINAL STORM FORECAST – 12/1 – 12/2

The question we’ve been trying to answer for the last 24 hours… is how do we get to that forecast.  We know that we are going to see significant upward motion north of the upper level low pressure.  The uncertainty, is where exactly that will be.  We’ve emphasized that there will be very sharp cutoffs between an additional 6 to 12 inches of snow… and an additional 1 to 3 inches.  That is appearing more and more likely to occur within the Hudson Valley.

It seems that those who are further to the east… stand likely to see the least additional snow… and those further west (especially viewers west of the Hudson River), could see the highest amounts.  Here is a computer model simulation of the radar on Monday…

Futurecast Radar : 4am to 9pm Tuesday

You’ll notice the changeover to heavy snow occurs first on the west side of the valley by mid morning, and then the entire Hudson Valley during the afternoon.  The focal point of the snow banding appears likely to occur within the Hudson Valley… or on the west side of the valley.  So that when we talk about ADDITIONAL snowfall amounts, this is what we expect by the time the sun sets on Monday….

Notice how the guidance wants to put the heaviest snow west of the Hudson River.  So much so, that parts of eastern Dutchess county and Putnam county may not see hardly any additional accumulation.  With upper level low pressure, comes very strong vertical motion… which generates heavy precipitation rates (in this case snow).  There is an offset to that, on the east side… where there is significant sinking motion, and that cuts off the precipitation sharply.  We will keep focusing on where that cutoff occurs… but if this guidance is correct.  Danbury CT will see 0″ of snow on Monday, while parts of Orange and Sullivan counties see nearly a foot of snow.  Pretty wild stuff.

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