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Forecast: Weekend Storm Not A Blockbuster — But It Will Be Messy03:13
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Snow will fall heavily before changing to sleet Sunday morning. (Dave Epstein/WBUR)
Snow will fall heavily before changing to sleet Sunday morning. (Dave Epstein/WBUR)

FRIDAY AFTERNOON UPDATE -- The models this afternoon continue to show a front thump of snow late Saturday evening followed by a change to sleet. It looks like the sleet might come an hour or two faster. As I've said, this would lower snow totals somewhat.

Otherwise the forecast remains on track with dry weather overnight and through Saturday during the day.

-- Earlier post -- 

There is a little bit of snow around the area this morning, but it's not going to accumulate. I am expecting temperatures to reach toward the 40-degree mark this afternoon. Aside from today's light snow shower activity, we have dry weather until the weekend storm arrives.

This won't be a blockbuster storm, but it will be a messy one.

At the front of it, after precipitation begins, will be several hours of snow. It could be snowing quite heavily from late in the evening Saturday through the wee hours of the morning Sunday.

During those hours you're not going to want to be out on the roadways. Accumulation rates could go as high as 1 to 2 inches per hour. Driving after 9 p.m. Saturday runs the risk of the roads being slick; after 11 p.m the visibility gets really low.

Snow will be falling heavily by around midnight Saturday. (Courtesy WeatherBell)
Snow will be falling heavily by around midnight Saturday. (Courtesy WeatherBell)

While the snow is falling, warmer air will be riding northward in the middle part of the atmosphere. This means that although it will remain below freezing over much of the area throughout the storm, there will be enough warm air above us so those little snowflakes falling out of the clouds melt and then refreeze as they come closer to the ground. This creates sleet — and it's a lot better than freezing rain.

Sleet will be a big player in the upcoming storm. (Courtesy NOAA)
Sleet will be a big player in the upcoming storm. (Courtesy NOAA)

Sunday A Mixed Bag

You can expect Sunday to be a messy day with rain over Cape Cod and a wintry mix north of the canal all the way up toward the Worcester area. North of there will be mainly a snowstorm, and that's where we could see 18-inch accumulations occur.

Since sleet is so much denser than snow, an hour or two of sleet will lower snowfall amounts by as many inches. If, ultimately, the air is a little bit colder and the sleet moves in earlier, the accumulation will be less than forecast. The converse is also true. I think the weather system winds down a few hours either side of sunset on Sunday, around 4 to 7 p.m.

A period of sleet, noted in orange is likely Sunday. The more mixing we see, the less snow there will be. (Courtesy WeatherBell)
A period of sleet, noted in orange is likely Sunday. The more mixing we see, the less snow there will be. (Courtesy WeatherBell)

There is a coastal flood watch posted, but any flooding with this storm should be minor to moderate; basically, expect what is typical of any winter coastal storm.

NOAA has posted a flood watch for the coastline. (Courtesy NOAA)
NOAA has posted a flood watch for the coastline. (Courtesy NOAA)

There may actually be some clearing to see the lunar eclipse late Sunday night but it's going to be very cold. Monday is the coldest day so far this winter, with temperatures staying in the lower teens and wind chills below zero. The temperature is moderate during the middle part of next week.

A lunar eclipse takes place early Monday morning. (Courtesy TimeandDate.com)
A lunar eclipse takes place early Monday morning. (Courtesy TimeandDate.com)

You can follow my updates here and on Twitter @growingwisdom.


Friday: A flurry; otherwise a lot of clouds and mild for January. Highs 35-40.

Friday Night: Clear to partly cloudy and chilly. Lows 15-20.

Saturday: Chilly and dry, snow at night likely, heavy before midnight. Highs in the 20s.

Sunday: A mixed bag of precipitation likely with a wide range of temperatures: 40 over Cape Cod, 30 in Boston, teens to New Hampshire. Rain over Cape Cod; sleet and some snow around Boston; all snow in northern New England. Hard freeze at night.

Monday: Blustery and very cold. Highs 10-17.

Tuesday: Sun and some clouds. Highs in the mid to upper 20s.

This segment aired on January 18, 2019.

Related:

David Epstein Twitter Meteorologist
David Epstein is WBUR's meteorologist.

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