Forecast discussion: A weak area of low pressure off the Gulf of Maine helped bring some scattered snow showers over eastern Massachusetts on Thursday. A coating to a half inch of snowfall fell, as some areas had sunshine for parts of the day. We may see another half inch of snow before the precipitation ends later tonight. However, we will be bracing for another blast of polar air the next 48 hours, making for bitterly cold temperatures.
During the overnight, skies will begin to clear, and winds may increase, due to the pressure gradient between the departing low and the high pressure ridge to our west. The mercury will plunge below zero north and west of Boston, and wind chill temperatures will make it feel like 15 to 20 below zero to exposed skin. There is a Wind Chill Advisory in effect from 3 a.m. until 10 a.m. Despite the bright sunshine, strong west-northwest winds will make it feel like 15 below zero, as temperatures only reach the middle teens.
The polar air remains over us Friday night, but winds will be diminishing through the overnight. So, it will still be cold, with highs in the lower single digits. We will begin to see increasing clouds heading into dawn on Saturday, as two weather systems approach the east. A weak low over the Great Lakes will keep the colder air over us for Saturday afternoon. So, any precipitation we see my 5 p.m. will be in the form of snow. As we head into Saturday evening, a low pressure system out of eastern Texas will slowly intensify, and help to pump more moisture in from the Gulf of Mexico. However, this low will also bring north some warmer air. At this time, it appears during early Sunday morning moderate snow will begin to change over or mix with some freezing rain, moving south to north. By the mid-morning, temperatures will be warm enough to mix with or change it to rain. I am expecting almost a half inch to inch of rain, so this will make any snowpack much heavier. So, if you still have a lot of snow on a flat roof, I suggest taking it off before the weekend. The heavier weight will create more stress on roofs. Also, patchy fog is possible, as the warmer air moves over the colder ground, especially with the high snow packs.
As we had into Sunday evening, the cold front associated with the low will begin to push through eastern Massachusetts. This will change the rain back to a wintry mix and back to snow before all precipitation ends early Sunday evening. High pressure will bring mostly sunny skies on Monday, but another blast of polar air returns Monday night, with temperatures falling back into the single digits. Temperatures will be slightly cooler on Tuesday, with overnight lows Tuesday night in the lower single digits. It will be warmer than Monday night, based on the fact we will see increasing cloud cover entering Tuesday.
Tuesday will remain dry, despite the cloud cover in the evening. However, I am a little unsure about the forecast after this time period. When I was looking over the American model today, it is showing a very quiet weather pattern for Wednesday. A series of weak low pressure systems passes through the region, giving us scattered snow showers. However, when I look at the United Kingdom, European, and Canadian models, I am seeing a totally different scenario. The other models show a low pressure system in the Great Lakes diving into the Mid-Atlantic States late Tuesday, before intensifying off the coastline for Wednesday. So, the other models feel a possible Nor’Easter will bring some substantial snowfall. At this time, my confidence is poor, due to the time period being five days away, and that the American model is not showing any type of developing low. For now, I will put moderate snow in the forecast, until I see more consistency in all of the models the next few days.
We end the forecast period with dry weather next Thursday, after the possible storm moves out to sea. Temperatures will struggle to reach the lower 20’s for high temperatures.
72 hour forecast:
Tonight: Passing snow showers end by midnight with clearing skies. It will remain breezy. We will see a low of 0 with wind chill temperatures falling to 15 to 20 below zero. A coating to an inch is possible.
Friday: Mostly sunny, breezy, and colder with a high of 17. Winds will come from the west-northwest at 16-20 mph. Wind chill temperatures will make it feel like 15 to 20 below.
Friday night: Partly cloudy and bitterly cold again with a low of 6. Winds will diminish to 7-10 mph from the west-southwest. Increasing clouds expected before dawn.
Saturday: Mostly cloudy skies with light snow developing by 5 p.m. and a high of 28.
Saturday night: Moderate snow with a low of 27.
Sunday: Snow will change to freezing rain by 7 a.m., and then changing to rain. We will see a high of 40. Patchy fog is possible during the afternoon.
Sunday night: Precipitation changes back to snow around 5 p.m. before ending at 9 p.m. We will see a low of 20.
Monday: Mostly sunny. Highs 24-27, lows 1-4.
Tuesday: Mostly sunny during the day, with increasing clouds by the early evening. Highs 22-25, lows 12-15.
Wednesday: Overcast with moderate snow possible. Highs 29-32, lows 15-18.
Thursday: Mostly sunny. Highs 23-26, lows 9-12.