One Two Punch Today...Is There a Knockout?
We've been painstakingly tracking this Norlun trough for days now it seems and it is finally moving through this morning. What a night is SW Connecticut I-95, I-84, the Merritt parkway at a standstill during the evening rush as 12-16" of snow fell from Bridgeport to New Haven! Hundreds of motorists stranded and delayed. At times snow falling at 2-3" an hour...while in New York City...only a few inches in the Park. The extremes of the haves and the have nots of Norlun trough on full display last night.
It has been hard to communicate this forecast. I know a lot of people were waking up wondering where is the snow? The shift came midday yesterday when we realized we were not dealing with two troughs...but actually one trough and a deepening ocean storm off the coast. This changed the timing and placement of everything...if you have not been closely paying attention to the weather...you may be wondering what is going on?
Round one( the Norlun Trough) is moving through Metrowest in a weakened state this morning. It is still providing moderate bursts of snowfall, reducing visibility down to mile at times...and enough for a general coating to 1" of snow. Roads are mostly wet on main well treated roads...but a slushy accumulation is gathering in spots. Also cold temps are stuck in the 20's. Any sort of light snow or moisture is freezing making for areas of black ice on any untreated roadways. Use caution this morning! This band of snow will continue to push north through Boston then up into Essex county to Cape Ann...where the band will weaken and fizzle as it loses it's upper level support and lift. Still scattered snow showers and flurries will resume...especially north of the pike into the afternoon. There may even be a few breaks of sun! The Cape is sitting pretty in the sunshine. Drier air will try to penetrate inland during an afternoon lull...temps climb to near 40 in spots.
The trough may weaken...but it is going nowhere. In fact it will play a role in tonight's weather. We turn our attention to round 2 coming out of the mid-atlantic. There is a huge upper low (cool pool of air aloft) sitting back towards Pennsylvania. This is steering more energy off the coast today which will turn into a deepening storm south of New England tonight. It will approach the benchmark and then quickly accelerate east by sunrise tomorrow.
I expect the snow to fill in quickly tonight and become heavier later tonight through the overnight hours tomorrow. The heaviest snow will be south of Boston. Judging by the track of the 850mb low the heaviest snow should track across Southeast MA. This is where the National Weather service has issued a winter weather advisory. The Energy off the coast will help to re-ignite the Norlun trough which will be stalled over southern New England...this could help to enhance surface convergence and produce some banding of snowfall right at the coast. Still even at this point of the forecast...we will still have to keep a close eye on the track of the low...just a few miles to the east or west could have major impacts on overall snow totals. The best chance of substantial snow will be from New Bedford to Plymouth to the Cape and the Islands. The Cape and Islands could exceed over 6" in spots...The Vineyard, Nantucket, Buzzards Bay and Outer Cape have the best chance. Boston snowfall will be lighter a general 2-3", with amounts dropping off North and west to a coating-2"...Some areas will get zilch.
The Upper low will slide south of New England and drag in cooler drier air behind it with gusty NW winds for Sunday which will feature a thinning cloud cover and partly sunny skies with temps in the Lwr mid-30's. Fair weather to start the week.....
So this quick one-two...nothing we can not handle...But is there a knockout waiting in the wings? I can tell you the atmosphere is loaded! Energy will continue to spill in from the Northwest US to reinforce a trough in the Northeast. The sub tropical jet will continue to steer in moisture from the Pacific and the Gulf. If this will all come together remains the big question.
Our next chance comes Tuesday night and Wednesday. This will be a quick moving storm...but have a more "classic" winter look. A low will come out of the Gulf and track up the east coast. Energy from the Northern stream will link up with this moisture and form a deepening storm south of New England. This should become a Nor'easter for us will the potential for significant snow accumulation...but we wait on that for now. Most guidance is calling for this storm to hit...but all vary on the track and amount of snow possible. This has the potential to be a major storm from the Mid-Atlantic to New England. Something to watch in the coming days.
The cold from NW Canada will continue the press into the Continental US...so by the time we get to the 20th...we could be in the heart of the coldest air we will likely see this winter.
