Watch CBS News

From Spring to Snow - Friday Flakes Expected

Near 60F Wednesday night, snow by Friday morning? Sure why not. New England weather has to live up to its reputation, right? The same front that's pushing warm air up the East Coast will help snow move back into the area to end the week. It's a tricky forecast and another 'on the edge' type of setup that will lead to some getting snow and others getting nothing at all. Remember last winter when these forecasts were so much easier? "Blizzard for all, enjoy."

Thursday is another incredibly mild day in the 50s (record high in Boston is 64F and that looks safe). But by Thursday night, a push of colder air will start funneling down from the north and west. Slowly we'll fall through the 40s and into the 30s, and that's when some precipitation starts coming back our way. This setup is called an 'Ana-front' - where precipitation falls on the cold side of it instead of out ahead in the warmer air. All this is aided by a ripple of low pressure that forms along our stalled front and helps to throw moisture back on southern New England.

eurotroughgfstrough

So what are the question marks with this forecast? One is a subtle difference in the tilt of the trough digging down into the east. The ECMWF is slightly more amplified and goes negative, which in turns brings the wave of low pressure farther west and the heavier precip along with it. The GFS and NAM are less amplified and more progressive...swinging an open wave up along the front and out to sea with minor impact. In my mind the ECMWF is the outlier here, because all of our higher-resolution and short term guidance is in the GFS camp. The NAM is farther east, the RPM is mainly out to sea, and the 4km WRF is reasonably positioned in the middle. It's a little alarming to see the Euro throw out some larger snow numbers and can't be entirely ruled out, but I didn't weigh it as heavily in the forecast.

temps

Temperatures early Friday morning a little above freezing, which should make for a wet snow. Source: Weatherbell

The other thing for us to watch is the temperature story. When this shield of precipitation works back west, it should initially fall as rain since temps will still be well above freezing. But after a few hours the air should cool down enough to flip to snow - and a heavy wet snow at that. It will fall on a warm and unfrozen ground that previously had rain falling on it, so that may temper accumulations a bit. The wet snow type also means snow ratios will probably be in the 6:1 to 9:1 range (meaning 6" of snow per 1" of liquid). That too may hold down totals some.

And finally, the back edge of these types of systems is always a royal pain. They disappoint more often than over-achieve, but that's not a foolproof bet. The most difficult part of this storm will be figuring out exactly where that back edge will be - because like the last storm the line will likely be very sharp between accumulating snow and nothing.

friday

Now that all those thoughts are out there...here's what I'm thinking based on region. The timing would be for this to begin shortly after midnight Thursday, and continue until about midday Friday before exiting the Cape.

Western Mass, New Hampshire, and northern Worcester County -

Likely not getting much of anything out of this. Maybe some coatings to an inch. As you were!

North Shore to Boston, Metro West, and southern Worcester County -

The potential is there for this line to shift a little either northwest or southeast, so these are the areas that should be most on guard for forecast changes over the next 24 hours. The bullish guidance brings some significant plowable snow into these areas, but my gut is that it will be on the lighter side, meaning a coating to 2"...possibly 3" of snowfall. Still something that could cause issues for the Friday morning drive.

South Shore to Mid-Cape, Martha's Vineyard, and the South Coast -

Best bet for significant snow is in these locations, which also means the highest impact on the Friday morning commute. Right now I'm thinking 2-5" of heavy wet snowfall.

Lower/Outer Cape and Nantucket -

Rain should hold on longer in these locations with warmer temperatures, and the flip to snow should take the longest. Considering that, totals should be lower in the coating to 2" range.

Find Eric Fisher on Twitter and Facebook

View CBS News In
CBS News App Open
Chrome Safari Continue
Be the first to know
Get browser notifications for breaking news, live events, and exclusive reporting.