Off Topic: History in the Making in New England

Rogue Nor'wester to Paralyze the Northeast US with Wind, Rain and Snow

For those of you just joining us, no that title is not a typo. You may be used to hearing Northeast US snowstorms referred to as Nor'easters (referring to the direction the winds typically come from during the worst of the weather), but that moniker doesn't apply to a storm like this. In fact, in the non-elevated parts of the Northeast that get the worst impacts from this storm, the wind will be howling out of the northwest!

As alluded to yesterday, a life-threatening and severe weather disaster is unfolding in the very areas that have largely been spared the worst of winter this season, as well as some parts of the I-95 corridor that have seen entirely too much snow already. In parts of Upstate New York and Central New England, 8-14 inches of snow has already fallen today in association with the first of three waves of energy diving into the US from the northwest. This first system would, under normal circumstances, be a notable winter storm for places like Elmira, NY, Worcester, MA and Williamsport, PA that haven't had much snow to talk about this season, but what is lurking for Wednesday night through Sunday morning is a much...much bigger story.

Late on Wednesday, an area of low pressure will begin organizing over the Gulf Stream waters east of North Carolina and an area of light snow will develop. This new storm will steal moisture and energy from what's left of the first low pressure system currently influencing our weather and bomb out during the day Thursday. As it does, arctic air will begin wrapping in south of the storm from the Northwest and Atlantic moisture will be thrown back as far as Southern Ontario, Canada to the north of the storm. This deep "negative tilt" (a phrase meteorologists use to describe a storm system which becomes intense enough that the trough of low pressure it creates leans NW to SE instead of the normal N to S or NE to SW) is in response to a strong area of high pressure and blocking over Northeast Canada and the maritimes. This blocked flow regime isn't going anywhere and the storm will be forced to drift much more slowly northwest until it eventually stalls somewhere in either Southern New England of extreme Southeast New York.

Once the storm arrives, it will be here for quite some time, only slowly weakening thanks to continued reinforcing shots of cold air arriving from the northwest. In fact, the center of lowest pressure is expected to simply die in place, rather than lifting out as we would typically expect. The result of this complex and incredibly unusual pattern will be a storm for the record books. Two large concerns highlight the disaster - on the warm side of the storm, hurricane force wind gusts are possible, particularly in eastern Long Island and the east facing beaches of Southern New England. Along with the wind will come 20 foot waves, severe beach erosion, and coastal flooding (associated with a storm surge that could reach 6-8 feet above normal high tide Thursday evening). On the cold side of the storm (well north of the surface low pressure and immediately west and south of its track), a raging blizzard is in the cards. With a storm as dynamically impressive as this, mesoscale snow bands that produce accumulations on the order of 2-4 inches per hour are favored. Unfortunately, the snow will, by in large, be very wet and heavy, producing the danger of roof collapse, power outages, downed trees, and associated health risks from attempting to shovel the snow.

The snowfall forecast graphic provided above does not reflect an additional problem with this storm. In the higher terrain of the Northeast, even in areas that get into the warm sector of the storm, heavy snowfall will be the primary precipitation type, and accumulations on the wind-facing slopes of mountains above 2000 feet could reach 3 or 4 feet, with even higher amounts possible in the Poconos, the Catskills and the Adirondacks. These higher amounts won't necessarily be the rule, but don't be surprised to see snowfall reports that exceed the amounts I've shown in the forecast map.

A severe winter storm is problematic enough when it occurs over the normal 1-2 day time scale. However, this storm will take 4 days to clear (and immediately follows another snow-maker already in progress), meaning air travel will severely impacted, less-traveled roads may remain impassable for right through the weekend, and if your power goes out, it may be days or even a week before it gets restored. Anyone in the areas targeted for the largest accumulations should take this opportunity to prepare. We're all used to making fun of the panicked shoppers who raid supermarkets to stock up on essentialls prior to a 6 inch snowfall in DC, but this is the one storm you really do need to prepare for in advance, especially if you live in a more remote area where emergency services may be slow to arrive.

As mentioned previously, the storm is likely to take on the appearance of a hurricane on radar and satellite when it reaches its peak, complete with an eye-like feature and neatly-wrapped spiral bands of rain and snow completely encircling it. It's not of tropical origin and should not be confused with the kind of storm this region might get during the fall, but it helps to underscore the danger the storm poses.

For the folks reading this in the DC area, you are dodging a bullet cannonball here, but there will probably be some light snows Wednesday night and very gusty winds on Thursday, so travel will be treacherous as snow blows back over plowed roads and makes things very slick.

There is still significant uncertainty in the exact track of the storm, the placement of the heaviest snow bands and the amount of mixed precipitation in many of the most populated areas affected by this once-in-a-lifetime event. If things change, I will update here.