March Cold Brings March Snow and Ice

This is impressive March cold. Temperatures in the valley and shoreline struggled out of the mid 30s with quite a bit of slow and gusty downslope winds. That’s hard to do this time of year.

It’s also pretty unusual that we’re talking about a winter storm bringing snow AND ice around the vernal equinox. More often than not the question in late March is “snow or rain?” and now “how much freezing rain will we get?” But alas, with strong high pressure anchored to our north and an anomalously cold airmass we’re setting the stage for a pretty impressive late season winter storm.

WVIT Forecast Snow SNE to CT - new

 

This storm will really go to town once it’s past our latitude. Northern New England is really going to get clobbered by this thing.  Still, the initial thump of precipitation will come down in the form of snow before transitioning to a wintry mix.

chart_3 (1)

 

This won’t wind up being a huge storm here in CT but it will be a much more significant storm to our north. It’s not because we lack the cold it’s because the storm really fires up once it passes Connecticut. Here’s the 12z European model which shows the low rapidly deepening to the northeast of us.

ecmwf_apcp_f54_us

 

By the time the storm’s comma head/cold conveyorbelt really organizes it will be to our north. For the brunt of the storm we’ll have to rely on the “front end thump”.

So what will that thump bring? Here’s the 18z GFS BUFKIT sounding for Windsor Locks at 5 a.m. tomorrow morning.

bdlbufkit

 

At 5 a.m. the GFS (which is on the warmer side of the guidance suite) is all snow at Bradley. What I want you to note, however, is that the best “lift” in the atmosphere is relatively low – centered around 800mb (see the white line on the left – that’s omega or vertical motion – the farther left the stronger the upward vertical motion). This is well below the dendritic growth zone. While it will be snowing dendrite production may be ugly.  This is not a sounding that makes me particularly bullish.

The 21z SREF guidance seems reasonable and fairly close to my thoughts with the odds of >4″ of snow better than 50/50 from BDL posint north and west.

f12s36

 

The SREFs have been horrific this winter – but it’s nice to see them on the same page as my thoughts. The NAM as usual is spitting out huge snowfall numbers as is the WSI RPM (their 12km WRF model). A GFS/European consensus brings a solid 3″-5″ of snow away from the shore and that’s what I’m going with. It’s possible places like New Haven may wind up with 3″ or 4″ too before getting washed away my rain.

This also looks like it will be a BIG storm for ski country in VT. I’m expecting 10″-20″ of snow on the spine of the Greens from Jay Peak down to Mount Snow Tuesday and Wednesday. The southern Greens get the bulk from synoptic snows and the northern Greens get the bulk from upslope. Everyone’s a winner in Vermont for a ski season that will be going very strong into April.

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