Boy what looked like a pretty simple forecast has quickly turned into a fairly difficult one.  The computer guidance over the last few runs has been trending towards the south and east with our storm.  Meaning that there is a better chance that many of us start as snow before switching over to rain.

But the real trouble arises when we try to figure out who starts as snow and how long does it take for the snow to change to rain!!!

What do we know for sure?

Currently our storm is taking shape over the Carolina’s (see image below), moving to the ENE offshore.  Offshore is where our storm will begin to intensify and it is here where it will phase with a piece of energy from the Polar Jet Stream (which is the dark shaded area over Missouri).  This phasing of the jets will allow for a fairly strong storm to develop.  (As a precaution, the National Weather Service at Tuanton has issued a High Wind Watch for all coastal communities along with Bristol and Plymouth Counties.)

We also know that this will be a particularly long duration event as precipitation looks to begin falling sometime after supper on Wednesday lasting through the day Thursday and wrapping up possibly overnight Thursday night.

But who will see some snow? Who will see all rain?  Who could see a mixed bag of everything?

Right now I believe that everyone outside of 495 will START as snow, but with time the temperature will slowly rise and we will turn over to rain for most.  Those who live in the higher elevations furthest away from the coast; western Worcester Hills and Berkshire could potentially stay all snow.  Those who stay all snow could be looking at 2-3″ possibly.  Those of us who start as snow can expect a coating at most.

One thing that we will have to watch for (and I believe this will happen) is that as we change from snow to rain there will be a time of freezing rain or sleet.  Reason for this is that the mid-levels of the atmosphere are forecast to warm before the surface does.  Let me explain:  Precipitation high up in the clouds starts as snow crystals.  As it falls it will remain as snow until the temperature rises above 32 F.  When it does, the snow crystal will begin to melt becoming a water droplet, where it will usually reach the ground as rain.  But there could be a time period where the ground is still below freezing, while the atmosphere is above freezing.  When this occurs, the snow flake that has melted does not have enough time to turn back into snow.  It either freezes enough to become sleet or it reaches the ground as a rain droplet and freezes on contact.

Again I expect there to be a small window where we will either see freezing rain or sleet, meaning that the roads and sidewalks could be a little slippery during this time frame.  Hopefully, this window will not occur during the morning commute, but there is always the chance that it will.

We all love pictures right, so here is my crudely drawn map of what the precipitation forecast could look like.

 

It’s pretty simple actually.  Places that stay all snow could get as much as 3 inches.  Places that fall in the mix category should look to start as snow (a coating for the lower elevations, possibly an inch or two in the Worcester Hills) but transition from snow to sleet/freezing rain to all rain.  And obviously those in the rain category will be all rain.

Again I would like to remind everyone that this will be a strong nor’easter and that winds at times could be quite strong.  We are looking at sustained winds of 20-30 mph with gusts as high as 50 mph inland; 60 at the coast, so scattered power outages (especially near the coastline) are possible.

One final remark…….we can only hope that this is the pattern that carries us through the winter. (If you like snow)

-Chris


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