1-18-2019 Midday Update

Good afternoon!

Before I update the storm, let’s take a quick look at the other elements of the next five days. Tonight will be around 14 degrees with mostly cloudy skies and a calm wind, and tomorrow will be 25 and mostly cloudy, with a light north wind.

weather 2019-01-18.001.jpeg

Beyond the Sunday storm, a very cold airmass makes a visit for a few days, with a high of 9 on Monday after a morning low somewhere around 0. Tuesday morning will be around -1, and then get to around 23 degrees with mostly sunny skies. There is a chance of snow and rain on Wednesday.

weather 2019-01-18.002.jpeg

Now, for the Sunday storm.

Timing and Precipitation Type
Snow begins during the 7-9 PM timeframe tomorrow (Saturday) evening. This could pose a few travel issues, but the serious problems don’t begin until later in the evening. Expect the heaviest snowfall to start after 9 or 10 PM. Heavy snow continues until mid-morning Sunday, when mixing with sleet will likely begin. A mix of snow and sleet – along with perhaps some freezing rain, though freezing rain is more likely to our south – continues until late afternoon, when all snow is once again likely for an additional light accumulation before precipitation ends during the evening.

2019-01-18 1330 PT.png

Uncertainty
The exact time of mixing beginning may result in some changes to the snowfall amount. I still think we will get walloped during the overnight and early morning regardless, but it could just add even more to the final number if colder air holds serve for a little while longer aloft. The exact positioning of the freezing point aloft is waffling on guidance, and we are very close to the freezing line aloft; where we are in relation to this will dictate exactly how much snow we get, but I still think a foot or more is very likely. It’s just a matter of exactly how much.

Snowfall Amounts
DISCLAIMER – The amounts below are subject to change!
I am expecting a widespread 12-20 inches of snow in northern Massachusetts, Vermont, New Hampshire, and Maine; this includes Dracut, as I feel that even if mixing is significant, we are in for enough snowfall – with high enough snowfall ratios, as cold air predominates overnight in this setup – to cross the one foot marker. I would not be surprised to see a few spots approach 2 feet, most likely in central and southwest New Hampshire and into southern Vermont. That said, the precise. location of the 12″ line could waffle a bit. Most of the accumulation in this zone is from snowfall overnight Saturday night and Sunday morning, with a little bit of it coming from sleet – and some light snowfall at the end – in southern sections of this area.

To the south is where this forecast gets a lot trickier, as there will likely be a somewhat sharp gradient between nearly a foot of snow and a few inches. I’m currently going with 7-12 inches of snow for the Springfield and Worcester areas, MetroWest, and much of the North Shore. Sleet will be a bigger problem here, and freezing rain is a serious concern for large parts of this zone. I have the 7″ line running directly through Boston, which brings us to the 3-7″ zone, covering the southern suburbs of Boston and northern parts of southeastern Massachusetts as well as northern Rhode Island. The 3-7″ and 7-12″ zones are low confidence, and a sharp gradient is likely in this area.

Further south, up to 3″ can be expected as freezing rain, rain, and sleet will be much more predominant in the south coast area after the initial snowfall, which will be much shorter.

2019-01-18 1330 SN.png

In the freezing rain department, I’m expecting this to be a bigger problem south of the Mass Pike, but a light icing is possible around here nonetheless. This event could pose some significant icing issues to our south.

2019-01-18 1330 ZR.png

I will update this no later than tomorrow morning!
-Nathan

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