Brief Meteorological Look
An innocent clipper system will be tracking southeast from central Canada and move right over southern New England. As this clipper system moves off-shore, rapid cyclogenesis (strengthening) is expected to occur. As the system begins to rapidly intensify, moisture will get drawn into the system and this will eventually lead to snowfall breaking out across the region. In response to the system rapidly strengthening, this will increase the pressure gradient across the region and this will yield to very strong to perhaps damaging winds developing, especially across eastern MA and the Cape area. With the wind component mainly from the north and northeast, this will reinforce brutal Arctic cold into the region with temperatures mainly in the single digits and teens throughout the duration of the storm. This coupled with the potential for very strong winds will yield to some dangerous wind chill values.
We will now do a breakdown of each associated hazard expected with this system and what we can expect with each associated hazard:
Snow
We will first look at the snowfall potential associated with this system. This will be an all snow event...no worries about any sleet, freezing rain, or rain mixing in as temperatures throughout the atmospheric column are more than supportive for snow. One thing with this system is, the precipitation really doesn't get cranking until the system is strengthening off-shore. This will lead to reduced snowfall totals the further west you go, however, the further east you go, this could yield to some significant snowfall accumulations (>12'').
During the day on Saturday we will see periods of light snow region wide, these snows will be associated with the clipper as it moves overhead towards the coast. Snowfall accumulations during the afternoon hours should be on the light side, perhaps a few inches in spots but the periods of heavier snow don't begin until we near the evening hours.
As we approach the evening hours and the clipper and energy aloft associated with the clipper begin to move off-shore, the strengthening process will rapidly begin to occur. As this happens stronger lift will develop across the region and more moisture will work into the system. This is when we will begin to see periods of moderate to heavier snowfall break out across some spots.
Due to the fact that this system will be strengthening off to our east instead of off to our southwest, this means the majority of the heaviest snows will be on the backside of the system associated with what is called the cold-conveyor belt (or CCB). It is this which will be key as to where the heaviest snowfall sets-up and where the highest snowfall totals occur. The big question with regards to the CCB is when does it begin to develop and take shape. This is something that needs to be watched, especially for CT and central MA as if this develops later as opposed to earlier it will mean reduced snowfall totals, however, if it develops earlier, that would lead to increased snowfall totals so this will be closely monitored over the next 24-hours.
We are looking at the time period from late overnight Saturday (roughly 2-3 AM) through late morning to about noon time on Sunday as the timeframe for the heaviest snows to occur. Across western and central MA down to western and central CT, snows should begin to taper off mid-Sunday AM.
Under the heaviest banding of snows, snowfall rates could approach as much as 4-5''/HR but this will not be the norm region wide...these totals will only be confined to the heaviest banding and where thundersnow is possible which is more likely to occur out across eastern MA. Elsewhere expect snowfall rates of up to 1''/HR at times.
Here are my initial snowfall projections but this will be further fine tuned tomorrow:
Wind will be a major issue with this system, especially out across eastern MA thanks to a very tight pressure gradient that will be in place with the near 970mb low just to our east. The combination of very strong winds and snow will yield to blizzard conditions at times, especially out across eastern MA and will also lead to very dangerous wind chill values. Winds out across eastern MA towards the Cape could gust upwards of 70-80 mph! These are gusts which will rival category 1 hurricane strength and would lead to widespread power outages along with big time drifting blowing and drifting of snow. As you move further west across southern New England the magnitude of the winds won't be as severe, however, we are still looking at winds gusting potentially upwards of 65 mph. These values are still strong enough to yield scattered power outages along with blowing and drifting snow. We will actually see winds becoming gusty during the day today and continue right through Monday with the peak intensity of the winds from tomorrow night through much of Sunday. If the higher end of these values are realized across eastern MA not only would we be looking at widespread power outages but outages lasting several days or longer. Here is a map showing the potential wind gusts:
Temperatures
Temperatures will be down right COLD. We are only looking at temperatures to be in the single digits to perhaps the low teens throughout the duration of this event as brutally cold Arctic air is transported southward thanks to strong northerly to northeasterly winds.
Wind Chill Values
The combination of temperatures only in the single digits to perhaps low teens and winds sustained between 20-30 mph (higher further east) with potential for gusts 60+ mph will yield very dangerous values at times. We could see wind chills range anywhere from -15F to as low as -25F during the storm. Those are very dangerous values and pose a high risk for frostbite in a very short amount of time. It is this reason, along with the accumulating snows that travel should not be done unless absolutely necessary. If you are out traveling and get caught this will pose a life threatening situation given the degree of cold we are dealing with.
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