bristolri_wx

That may have compacted overnight. I was in the 6-8” range earlier overnight. Thankful it never really fully changed to rain or sleet here in Bristol. Of course as usual most of the heavy stuff stayed north of here after the first few bands went through.

Area Forecast Discussion National Weather Service Boston/Norton MA 425 AM EST Thu Dec 17 2020 .NEAR TERM /THROUGH TONIGHT/... Winter storm continues to affect Southern New England early this morning. Regional radar shows west to east oriented bands of heavy snow, which have reportedly produced snowfall rates up to 2 inches per hour at times, now beginning to lift north of the Mass Pike. Water vapor imagery shows a dryslot on the southern end of the cyclone`s 700 mb circulation (this feature over east-central PA), and this dry slot is racing northeast from Long Island into a part of southern CT/RI. In a nowcasting sense, this dryslot has led to brief improvement in visibility (1/2 to 1 SM) across Hartford to Willimantic CT to central/southern RI eastward into southeast MA, with sleet at times mixing in. Speaking to temperatures, a coastal front has set up from roughly Beverly to Norwood to North Smithfield with ENE winds. Temps have been very slowly but steadily warming east of this front; with most areas in Norfolk, Plymouth and Bristol Counties hovering around 33-34F; upper 20s to around 30F into the Boston area and up into the North Shore. More northerly winds in the interior on the west side of the front has led to temperatures commonly in the upper teens to low 20s! We continue to have multiple weather-related concerns specific to this winter storm. Accumulating snowfall is one of them. Rapidly falling temperatures and a related flash freeze of snow/slush is looking likely later this morning across South Shore into southeastern MA. This may extend as far north as the Boston metro area, potentially affecting I-95/Route 128 and the Southeast Expressway. Strong northeast winds and minor coastal flooding are other concerns. Our surface low, a sub-1000 mb low just off the NJ coast, will continue to pull NE into the waters near the Islands by late- AM/early-PM, then move into the southern Gulf of Maine later in the day today. The 700 mb cyclone will continue to progress eastward into northern CT/western MA on into interior northern New England. On the snow accumulation forecast: I`ve made only small adjustments. The most significant of these changes was a reduction in snow totals from Windham County CT ENE across much of RI and into eastern and southeast MA by about 1-2". Much of these same areas should still see values nearing 1 foot, but the dryslot moving in may keep these areas from achieving foot-plus levels. On the other side, I`ve boosted snow totals across northwest and northern MA as deformation- zone banding on the northern end of the 700 mb low now across eastern PA looks to advance into these areas. Snow totals here were increased by a couple inches, mainly north and west of a Springfield to Worcester to Bedford line. Some of these areas from the east slopes of the Berkshires into the Route 2 corridor may see accumulations nearing 20". The forecast otherwise remains essentially unchanged. For a large part of Southern New England, snow intensity for today should be more of a steady light to moderate intensity. The exceptions are for the aforementioned northwest/northern MA area, with a secondary local maximum hinted at by the 00z HREF, NAM and GFS across the North Shore, Merrimack Valley into part of Metro Boston mid-morning into the early afternoon. For this secondary area, I am thinking that snow intensity may struggle to get to heavy levels especially by late morning as moisture in the snow growth region becomes unsaturated per NAM/RAP fcst soundings. Snow should taper off in interior MA, CT and RI by around mid-day, and by mid afternoon towards eastern MA. Periods of ocean effect snow showers may continue to affect Cape Cod and parts of coastal Plymouth County until evening, but the heaviest of the snows will have ended. On the flash freeze potential: as winds flip to N and NW by mid to late this morning, upper teens to mid 20s temperatures now in the interior will surge southeast. This leads to the potential for a rapid freeze-up of slush and snow, with highest confidence of this occurring across Bristol, Plymouth and Norfolk Counties where current temperatures are above freezing. Temps are very close to freezing in Suffolk County/Boston area that there is the potential for such even into Boston, but the better potential looks to be just south. On strong/gusty winds: High wind watch continues for the Islands until 10 AM. It is still quite gusty out on the islands, but damaging winds haven`t materialized. There may still be another window of opportunity for gusts to increase. Gusts to 30-45 mph will also continue across coastal MA, with gusts in the interior up to 30 mph. This will lead to blowing and drifting of snow.

Windy down here. Tough to take an actual measurement with drifting but I’m going to estimate 7-8”. Mostly light snow now with some sleet or icy snow mixing at times - can hear it hitting the house.

Radar looks like garbage south of Block Island, but it also looks to be regenerating a little right at the coast... so maybe the "dry slot" will stay off shore... looks like sleet is moving into Westport/Dartmouth and areas east going towards the cape... seems like sleet line is having trouble getting west of that...

RI looks like it's gonna be slammed next hour or two based on OKX and BOS radar...

https://weather.cod.edu/satrad/nexrad/

29 degrees, light snow, but picking up and sticking in the last few...

For the RI & SE/MA folks on the board. Not buying 37 and 38 degree surface temps on the NAM and HRRR that far into RI and SE MA.... 850 temps stays below freezing well off shore... we shall see!

Thanks for painting that yellow mix line literally right over my house. It's greatly appreciated!

I was a senior in 95/96 in RI. Had more snow days that year than in any of the previous 12 I had been attending school. It was glorious!

Yes, people will be pleased just because there hasn't been a widespread 6"+ event in over a year and half, especially for those in the coastal plain. Most of the storms over the last 2 seasons have been more localized for SNE in terms of snow accumulations.

I feel like the NAM has a tendency to bring that coastal front at the surface in a little farther than reality in these types of setups. Move that line about 35 miles SE...

In Cumberland? You're golden there. That is usually jackpot #2 in RI. I'm in the more worrisome area as usual - the bay is never my friend in snow events.

If only he read this forum and knew about the SW trend. His Twitter forecast is 50 pages behind this thread. LOL

The 48HR HRRR is just another map to look at - one thing to consider is that I believe at some point, that the HRRR will be updated and eventually replace the NAM in the future - though I may not be remembering that correctly. So the 48 HR HRRR is kind of the "New HiRes NAM" in testing mode...

18Z HRRR for those interested. It runs out 48 hours every 6.

12Z GFS incoming... I predict cutter up the CT river... bullseye of 36" of snow in Waterbury...

He's probably excited because we haven't had a real snow storm or snow pack down here in over a year and a half...

The DGEX and NGM running on the Commodore 64 in JoeSnowBOS's basement is in agreement. But otherwise, not one other model looks like its in the GFS ballpark at the moment...

GEM looks good.

GFS most consistent? Not really... Also, I believe (but not 100% sure) that the NAM had same full sampling as GFS at this point, so if sampling was a variable there should have been a similar outcome, but they are rather different at this point.

I don't know if that was on air, but it was definitely on their web site, and maybe their Facebook page. I saw a handful of people re-post it last night and this morning on my Facebook feed, and got a few questions about it. Clearly some people thought that was the forecast.

From my eyes, GFS looks even more SE at hour 78/84.