Winter Storm Warning Tomorrow- Little To No Impact Until Evening

A *Winter Storm Warning* is in effect from 8 AM Wednesday to 8 AM Thursday for Southern New England mostly SOUTH of the Mass Pike.

NWS PM Headlines

That said, I expect LITTLE TO NO IMPACT until tomorrow evening.  Especially when compared to the past 3 systems, this one has an unimpressive structure and will not be organized nor strong enough to generate heavy snow bands during the daylight hours.  The storm will also have to overcome dry air.  Tomorrow night is a different story.  The low will be closer, a little stronger, and won’t have to deal with the hazardous effects of the March sun angle.  The one exception is likely the South Coast. Cape, and Islands where snow will be able to accumulate tomorrow afternoon.  So if schools start dismissing early tomorrow, I may have to write a strongly worded letter (and offer a consulting fee).

General Overview

Here is the system on satellite tonight.  It looks pretty good, but it’s not as consolidated as we’d like it to be (for a big snowstorm anyway) with multiple areas of convection.

GOES 16 Upper-Level Water Vapor (image College of DuPage NEXLAB)

What I mean by that is look at the various zones of precipitation across the Eastern US.  Snow or some sort of wintry precipitation is falling in PA/NJ and just south of NYC.  Thunderstorms are moving off the Southeast coast while another piece of energy rotates through the lower Ohio Valley.

WSI Intellicast USA radar

On the surface chart, we can see this starting to come together by 8 PM.  But it really won’t be able to because there are too many moving parts competing for energy.  So the low closest to Southern New England gets shunted out to sea.  So even though it looks like the snow is close, it will not make it into Southern New England tonight.

WPC Surface Fronts/Precipitation Tuesday 8 PM

The projected surface chart for tomorrow morning shows the low well to our east while the southern lows consolidate near the Mid-Atlantic coast.

WPC Surface Fronts/Precipitation Wednesday 8 AM

Although this says some light snow is possible at 8 AM, I don’t buy it.  The air mass is very dry.  It will take most of the day for the atmosphere to saturate.  But enough with the technical talk.  I generally try to avoid it but I want to explain why my forecast may be different than the one on your cell phone.

Timing and Impacts

The first true snow band will not arrive in Northern RI/Southern Worcester County/Greater Boston until around 5 PM.  It will start earlier in Bristol/Plymouth/Barnstable counties as well as Southern RI and the islands.

18z NAM hires Simulated Radar Wednesday 5 PM (image

I will admit this is the part I am most uncertain about.  If the storm tracks a bit closer to the coast accumulations could start around 3-5 PM.  I’ll be watching the high-resolution guidance tomorrow AM.   But after 9 PM or so, its game on with heavy snow bands rotating in off the ocean.

18z NAM hires Simulated Radar Wednesday 10 PM (image

In these bands, snow will fall 1-2″/hr.  The snow will continue to fall until 6-8 AM in Southern New England.  Its basically a Wednesday evening commute to Thursday morning commute storm.  Surface temperatures will in the upper 20’s across Worcester County and Eastern MA.  But temperatures above the surface will be relatively warm so the snow consistency will be closer to the storm two weeks ago than the storm last week.  Given the weakened state of our trees, more power outages are possible even though winds will be less than the first 3 storms.  As for totals, here is what the National Weather Service is thinking.

NWS Storm Total Forecast

I would drop the totals a bit near Hyannis and increase them a bit in Northern Worcester County and Northeast Middlesex County.  I also think Springfield will be closer to 8″.  Generally speaking, a large area of 6-10″ is what I am going for.  That would mean delays and yes cancellations are in play on Thursday.  I’ll do the best I can to update tomorrow AM but certainly tomorrow late afternoon/early evening.

Where could this go wrong?  The consolidation of energy could happen too far south and east for any substantial snow in Southern New England away from the Cape and Islands.  I have to mention that possibility.

-Zack Green

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