After an eventful start to the weekend, we’re back underneath high pressure today which means the skies will once again be quiet. Look for mostly sunny skies with just a few clouds up in the north and mountains especially midday into the afternoon. Temps will be seasonably cool, ranging from the high 10s up north to mid 20s in the south.
For those curious, our storm chase to Cape Cod was a great success as we saw strong winds over 60mph, heavy snow of 1-3″/hr, and significant storm surge flooding all while remaining (mostly) warm and dry. Perhaps my favorite picture from the event is included below and shows me watching the ocean as snow, sand, and sea spray drifted past at 60-75mph.
It is, for those of us who love snow especially in large quantities, Christmas Eve. Anticipation will be building today as high clouds thicken up, winds start to flip around to the north, and a few appetizer flakes begin to fly. Mostly though it will just be quiet as a cold front slips through. High temps will range from around 20 up in the north to the low/mid 30s right along the coast.
The rest of this update will go into fairly great detail regarding the forecast for tomorrow’s blizzard.
If you love snow, the satellite loop below is what you dream of every August while you wipe sweat off your brow at the mere thought of moving.
If you don’t dream in satellite imagery, here’s why this loop is showing such a potent setup. First notice the two swirls diving southeast through the plains, one just about to enter Minnesota and the other crossing into Missouri. These disturbances are joining forces with another that’s a bit harder to see over Texas, and will help produce exceptional rising motion in the atmosphere over the East Coast.
That rising motion is already apparent in the brightening of the clouds on the loop (not in the real atmosphere, just how the colors work here) over the East Coast. That southern band of gradually brightening values from Texas to NC is also hinting at a deep reserve of rich tropical moisture. Any time you have powerful lift, deep moisture, and strong upper level disturbances joining forces, you know you’re in for a show.
A show is exactly what we’re going to get as low pressure emerges off the Florida coast in just a couple hours before racing northeast. The storm’s pressure will drop about 50mb in just over 24 hours which is approximately double the criteria established for being dubbed a “bomb cyclone”. By the time the storm crosses the Gulf of Maine tomorrow evening, it will have a pressure similar to what we’d expect to see in a category 2-3 hurricane. Though because our storm’s power comes from clashing airmasses, its energy will be spread over a wider area and thus winds will be a bit lower (though not by that much!).
As far as timing goes, look for north winds to pick up overnight and start shifting around to the northeast. The airmass just to our north is Grade A Canadian Arctic air – far northern Maine (outside the area for which I forecast) will drop into the 20s below zero tonight – which means that precipitation will initially struggle to push north as the first volley of snowflakes evaporate before reaching the ground.
We’ll have to wait until a few hours after sunrise for the show to really start.
Meteorologists quantify the clashing of airmasses by computing a parameter known as frontogenesis, shown in pink on the map above. This parameter, meaning literally “the creation of a frontal boundary between two airmasses”, points us straight to the heaviest snow bands and can give us a clue about their intensity. Tomorrow morning, frontogenesis values will be as high as the atmosphere can ever push them in a band extending from the storm center somewhere off New Jersey up towards the Gulf of Maine. In a more practical sense, that means that we’re in for some very, very, heavy snow.
Though there’s still some uncertainty, all indications are that we will find ourselves on the cold side of the storm’s warm front, certainly at the surface and probably through the rest of the lower atmosphere too. This is important because snowflakes like to grow best under the conditions found west of the warm fronts aloft. To get the picture-perfect six-pointed dendrites that pile up quickly in powdery drifts, you need a large portion of the lower atmosphere to be between -12C and -18C, as well as saturated and you need to have air rising rapidly through that layer. All those boxes are going to be checked along the Maine coast (as well as the foothills) tomorrow, especially during the afternoon.
The net result of all this is that for a period tomorrow, snow will fall extremely heavily and will accumulate rapidly. Snowfall rates of 2-4″ per hour are expected along the coast and southeastern foothills. As you get farther into the mountains, and away from the storm’s center, you’ll start running short of the moisture and lift needed to maintain the most prolific snow banding. That said, snow will still be pretty heavy in the mountains especially tomorrow evening.
The peak of the storm will come tomorrow from the late afternoon into the evening as the storm reaches its peak intensity east of Cape Cod. From a meteorological perspective, there’s essentially nothing you could do to make this storm more ferocious. It’s of the same kin that unleash fabled gales on the Viking coasts of the far North Atlantic. It will have a region of calm conditions at its center, somewhat analogous to a hurricane’s eye (though caused by different forces) flanked by hurricane-force winds of 75-85mph.
At some point in its journey, the storm will attempt to turn back to the northwest and perhaps even west, executing the rare loop maneuver we associate with New England’s most famous storms. The biggest question at this point is whether the loop occurs, and if so, where it might take place. This is important because whoever is sitting 50-100 miles west/northwest of the storm as it completes this loop will see the heavy snow band stall overhead. At the moment, it looks like the best shot of a loop sits between a point somewhere south of Block Island RI (at the western range of possibilities) and somewhere east of Cape Cod (at the eastern range of possibilities). That puts the lucky pivot point, where I expect 3-4 feet of snow to fall, just to our south somewhere between Providence RI, Sandwich MA, and Boston. However, if the storm decides to make it a little farther up the coast, this zone could extend into southern coastal Maine.
So what do I think is most likely?
Here’s my best shot as of this morning. Every line and every point was agonized over but at some point you just have to say this is my best guess and see what happens. There will be a very sharp gradient in totals over our area. I think a solid foot and a half to two feet (or, possibly, more) is a good bet along the southern coast into possibly western portions of the Midcoast. East of that, I’m worried about warm air at 10,000 feet or so, not necessarily because I think we’ll change all the way over to sleet (though at Rockland you never know) but because even marginally below-freezing air at that level cuts way into snow ratios.
To the northwest, it’s all about the gradient between the extremely intense snow band and intense sinking motion (no snow) to its west. I think the band will eventually push far enough into the mountains to give most of ski country a fluffy 6″ or so. In the foothills, you’re closer to the storm but I’m worried about downsloping cutting into totals a bit especially south of Mount Washington.
If you’re going jackpot hunting, eastern MA is the place to be for this one. I tweeted last night that I do believe somebody somewhere will get over three feet of snow from this storm given the moisture, cold air, and dynamics involved.
Another key aspect of a storm this intense is the wind. Thankfully we won’t see the core of the wind from this storm and the north/northeasterly direction bodes well for both keeping speeds down a bit and keeping the trees up (remember it’s southeast that’s the Achilles heel of our trees). That said, the coast should have no problem gusting above 50mph which, combined with the heavy snow, will lead to whiteouts. Blizzard warnings have been posted accordingly along the coast, though conditions just inland won’t feel that much different.
Things will settle down overnight tomorrow as the storm roars into Nova Scotia. By Sunday morning, we’ll just be left with some flurries and patchy blowing snow.
I’ll be riding this one out from Cape Cod so in the likely event that I become disconnected from the power grid and/or internet, my next update will be Monday morning.
Today will be another quiet one as a cold front begins to approach from the west. With bitter cold air in place across the area this morning, as winds turn towards the south, some ocean effect clouds and flurries are starting to move onshore at the moment. That will continue especially up in the Midcoast where flurries will be possible throughout the afternoon. I don’t see any noticeable accumulation though. High temps will range from around 10 up north to around 25 along the coast.
Today will feature clear skies, quiet weather, and cold temps as another Arctic high pressure system slides into the area. Look for morning lows near or below zero to rebound into the low single digits up north and mid 10s along the coast. A steady 10-15mph NW breeze will keep windchill values at or below zero throughout the day. The upshot is that there will be plenty of sun around the area.
Today will feature seasonably cool temps and a gradual transition from sunshine to overcast as an Alberta Clipper approaches from the west. Look for highs in the mid 10s up north and upper 20s down south. While clouds will have overspread the area entirely by sunset, precip should hold off until after dark. Snow will fall overnight into tomorrow morning with a general 1-3″ expected. Totals will be highest along the Midcoast where some localized banding may set up as the system starts to draw on Atlantic moisture.
Today will feature partly to mostly cloudy skies and generally quiet weather as a weak clipper system rolls in from the west. Winds will turn towards the southwest which will boost temps to around 20 up in the mountains and 30 along the coast. The milder air will also come with abundant cloud cover though, with just the coastline having a shot at some sunny breaks early in the afternoon. The clipper will have just enough moisture to bring some snow to the surface, mostly after dark and mostly south of Portland. Accumulations will mostly fall within the dusting to one inch range but I wouldn’t be shocked to hear of a 2″ report or two given that there will be plenty of “fluff factor” given the cold airmass and favorable snow growth.
Canadian high pressure is in charge of our weather today which means we’ve got mostly clear skies and cooler temperatures in the forecast. Look for highs ranging from the mid single digits up north to the mid 10s in the south. A light northerly breeze will make it feel closer to zero. Skies should remain mostly sunny throughout the day with just a few high clouds drifting past southern areas from time to time.
A cold front is on its way offshore this morning and winds across the area will flip around to the northwest shortly if they haven’t already done so. Most of the precip associated with this system is now off to our south though some sprinkles can’t be ruled out over the next couple hours in southern NH. Skies will start off overcast across the area today but will clear from northeast to southwest midday, with the exception of the usual mountain upslope spots. Despite the sunshine, your high temps are whatever you’ll step out the door to this morning. That’s about 20-25 inland and 35-40 closer to the coast. By sunset, the mountains will be approaching the 0 mark with 10s in the foothills and low 20s along the coast. NW winds will be breezy but should remain firmly in the nuisance category of 20-25mph outside exposed spots in the higher terrain.
Today will feature milder temperatures and some light snow in the north/mountains as a clipper system approaches from the west. We’ll be on the southern side of this system meaning warm air will be moving in on southwest breezes. As per usual, this effort will be most effective along the Midcoast, CT Valley, and southern NH while the foothills/mountains and our reasonably fresh snowpack keep colder air locked in farther north. With that in mind, look for highs in the low 20s in the mountains, upper 20s to low 30s for most of the foothills, and mid 30s farther south. The Midcoast peninsulas, where a SW wind is somewhat onshore, could get up above 40.
Any time warm air is overtaking cold air, we have to think a bit about precipitation. The clipper is producing some light snow to our west this morning, but it’s a bit short on moisture. As a result, snow will be steadiest up in the mountains where up to an inch or maybe two could pile up. Farther south, flurries are possible especially this morning but they won’t be of any consequence. A few foothill towns might see a brief period of freezing rain/sleet as warm air is able to advance more effectively farther off the ground.
Today will feature quiet weather with breezy WNW winds and cool temps. Look for the usual upslope/downslope pattern with clouds and maybe some flurries in the mountains while the coast is clear and dry. This afternoon, mountain clouds will gradually dry up. Temps will range from around 10 up north to around 25 along the coast.