I’ve missed two of the three big snow events that impacted the NYC metro area…but I’ll be here for what could be one of the highest impact weather weeks (for the nation as a whole, if not for the immediate East Coast…though we’re still in the ballgame) of the last twenty years.
In plain English, this is the general long range forecast for the coming three weeks.
THE WINTER TO DATE: The La Nina pattern tends to favor a weak southern storm track, which leaves room for ridges of high pressure (and maritime warmth) to stick their noses northward along the US Eastern Seaboard. As such, my seasonal forecast was for the bore of the cold and snow to be further back toward the Appalachians and Great Lakes and not along the New England coast. I was at least partially wrong. If you live in DC or Baltimore or even Philly, I look like a genius. All winter, storms have been struggling to develop early enough and strongly enough to pull cold and snow down into the Mid Atlantic, but even I can’t deny that it’s been considerably colder in this neck of the woods than I anticipated. Perhaps I underestimated the potential impact of recent arctic vulcanism and the delayed cooling effect of an extremely inactive solar cycle…or even the potentially destabilizing influence of the changing of phase of the Pacific Decadal Oscillation. But if you live in New England, where it has not, in fact, been all that cold, but it has been extremely snowy, my forecast looks idiotic. Storms continue to favor development around the barrier between the gulf stream waters (a natural source of heat and energy) and the unusually cold coastal waters draining down from Canada. They develop late (classic La Nina influence) but this year, with an abundance of cold air in Canada, they have been able to produce record breaking snowfalls in New York City and enough snow to collapse rooftops and power lines throughout Southern New England.
CURRENTLY: The end of this brutal winter is, however, being nicely telegraphed by current weather patterns. The Southeast US, which has battled an unusually large number of significant snow and ice storms (and is doing so again) has had some very mild days of late as the La Nina ridging begins to assert itself over the waning winter chill. Virginia Beach hit 71 degrees this past Wednesday, as a matter of fact – not far off their record high for the date (76). This ridging helped to guide the last major storm northward toward Chicago, where 18 inches of snow and three hours of thunder and lightning crippled the city. Unfortunately, with Canada harvesting most of the world’s supply of Arctic air as blocking ridges dominate the weather on the other side of the globe in Siberia, this impressive winter season is preparing to deal out what could be a knockout punch as the spring warmth in the Southeast returns to battle the final release of the polar vortex into the Great Lakes and Tennessee Valley.
THIS WEEKEND: Before the big show, a minor event will set the stage in the New England as a weak coastal storm will likely drop 4-8 inches of snow and help to usher in much cooler air from the “baby vortex” (a weaker cool air mass that develop in situ over Eastern Canada and Hudson’s Bay) for much of the Lakes and Northeast while ridging returns to the Southeast. Meanwhile, a strong Pacific storm is brewing that will send its energy downstream rapidly and help to carve out a trough over Texas by mid week.
BIG TICKET POTENTIAL: With a forecast looking as far out as this, there is of course ENORMOUS uncertainty with any details beyond gross generalities. It seems relatively likely, for instance, that the Southeast will be experiencing warmer, wetter weather by midweek as Texas is plunged into the deep freeze. It also seems likely (most of the models have been insistently showing this for days now) that by Wednesday, a major (and for some places final) charge of Arctic air will be underway. Temperatures could be 30 or 40 degrees (F) colder than normal for a day or two in the Northern Plains and upper Great Lakes and nearly as chilly in the high plains right on down to the Rio Grande Valley that marks the Texas/Mexico border – a true “blue norther”. The exact timing of the large thrusts of energy and rotation in the upper levels of the atmosphere that will drive whatever storm develops on the Gulf Coast of Texas and the push of arctic cold will be critical, but there is at least the POTENTIAL, given the extreme clash of air masses about to take place, for a tremendous storm.
To put this in perspective, then ten-day analogs (a term meaning most similar previous weather patterns to the current forecast for ten days from now) include March 06-10, 1993 (Superstorm ’93), late January, 1966 (100 inches of snow in three days in Oswego, NY…the first 48 of which from a huge inland blizzard…the rest from Lake Effect following the blast of record setting cold), and the “Great 78” Superior blizzard (previously the record-holder for the deepest low pressure system ever to form over land in North America…a storm that hit 959 mb and sunk dozens of boats in Lake Superior). Let me be clear – analog forecasts should be taken with a grain of salt. There will never be another storm exactly like the March ’93 superstorm or the great ’78…no event can ever be replicated in a chaotic atmosphere. However, three of the greatest “centennial scale events” in US history have shown up in the analog packages from various global weather prediction models at the same time…I believe it that someone…somewhere…east of the Rockies…is about to be dealt a hit they’ll remember forever. I have no idea where, right now, but this pattern is loaded with all kinds of potential to end with disaster.
FOLLOWING WEEK: After whatever event follows this mid-to-late-week storm, wherever it may go, I believe we are likely (>25%) to see the polar vortex unload body and soul into the Northeast US…emptying eastern Canada of its’ reservoir of cold air and delivering a three-day period of cold that’s hard to find a match for in the last half-century. But I have good news…traditionally, when the cold unloads all at once…it reaches a point where it runs into the warm Atlantic, the jet stream intensifies from the increased temperature contrast at the arctic front, and the trough is forced to “belly under” and lift over Greenland, opening up the entire US east of the Rockies (and much of Canada) to warm, westerly Pacific winds. When this happens in mid-February, it is very…very rare for cold air to build up quickly enough over Western Canada to reach the populated East Coast before winter has reached its’ end. It will get colder than normal again in late March or April…but by then, it will likely be far too late to see significant snow in the I-95 corridor…in the meantime, what will begin with a gentle slow warm up, will turn into an excessively warm March…it will feel like May in the Mid Atlantic South of the Mason Dixon line. In New England, it will take longer for the warmth to reach its’ peak, but even Boston should be feeling its’ first 60-degree days before the end of March.
That is my current long range thinking…feel free to laugh at me when I’m proven wrong. 🙂 But do keep an eye on the weather this next week…I have a strong feeling something impressive is about to happen.