Wednesday, 11:45 a.m.
Another arctic cold front is racing southward into North Dakota and northern Minnesota today, and while there is a 'spike' of temperatures of sorts ahead of this boundary (that is toasting the machine-generated numbers again), the air is quickly turning bitterly cold behind it. All of this is surrounded by a lot of wind that is picking up and moving the snow on the ground around quite a bit, and it is only adding to how miserably cold it already feels outside.
In another viewing of 'Groundhog Day', we're flipping the calendar to the end of February now, with normals 5 to 7, even 8, degrees above what they were in the depths of winter some five or six weeks ago, yet we're replaying the same pattern. Another blast of extremely cold air emanating from central and northern Canada unleashed on the northern Plains and Midwest, an air mass that will find its way easily deep into the South and to the East Coast over the next 36 hours. Yes, it will invade these areas that fast from its current location along the border. Here's the 12z Feb. 26 NAM 850mb forecast, which may best capture the low positioning and the packing of the isotherms that best represents where the frontal boundary will be:
While the low may be over Maine and southeastern Quebec at that time, the front will arc out of it off the New England coast and probably be clear of the North Carolina coast as well. High pressure will then build into the Ohio Valley tomorrow night, setting the East up for a bitterly cold day on Friday, though without the strong and gusty winds of this afternoon and again tomorrow.
Now, as this whole thing crosses the Upper Midwest late this afternoon and evening, there will be some snow showers in portions of central and northern Wisconsin into the Upper Peninsula of Michigan. That will morph into lake-effect snow over the western portion of the Lower Peninsula of Michigan behind the arctic front tonight. Then, tomorrow, snow showers and a few more intense squalls will rock northern Pennsylvania and upstate New York into New England. The snow amounts will hardly be great in these, but the intensity may mean some quick whiteouts with dangerous travel conditions for relatively short periods of time, but ones that could pop up in a very short period of time. Of course, more lake-effect snows will follow from the eastern Great Lakes tomorrow afternoon into tomorrow night as well.
Because there is no downstream blocking, the trough rotating through the Northeast tomorrow afternoon will pull the coldest air quickly out of the way Friday night and Saturday. Look at those same projected 850mb temperatures late Saturday:
Another one of these weak upper-level features will move by the Great Lakes and New England later Saturday into Saturday night, and while some light snow may fall out of it, there could just as easily be a passing shower from southern Indiana and southern Ohio into central and southern Virginia. The main impact of this feature will be to pull a cold front south through the Great Lakes and Northeast Saturday night, a feature that will then stall on Sunday from parts of the mid-Atlantic into the Ohio Valley.
Then it gets interesting.
Warm, increasingly moist air will continually be pushed to and over this front Sunday into Monday. This will lead to clouds along with some precipitation. Eventually, a storm will form in southeastern Texas and Louisiana late Sunday and Sunday night, a storm that will then head northeastward toward the mid-Atlantic coast Monday and Monday night.
For the Northeast, this means no storm this weekend, contrary to popular belief that you might see out there on social media, but there will be one to open up the week. Where the arctic boundary sets up Sunday will play a critical role in determining who gets mainly snow from this whole thing and who gets a mixed bag of wintry precipitation. What's also a wild card in all of this is the intensity and timing of the actual storm, as it will help in figuring out just how much water gets squeezed out of the atmosphere, and, therefore, how much snow may fall. While the models will no doubt change between now and Monday, here's the 12z GFS 48-hour QPF forecast from Saturday evening through Monday evening:
It should be noted that severe weather is quite possible with this developing storm late Sunday or Sunday night into Monday from Louisiana into the Deep South.
At this early juncture, suffice it to say there is a reasonable chance of a significant snowstorm from parts of the Ohio Valley into the Northeast. Regardless of how it all plays out, it will turn colder again behind the storm, though right now it appears as if the worst of that second bitter arctic blast will be aimed at Montana and the Dakotas into Nebraska. Temperatures could easily be 35 to 40 degrees BELOW NORMAL for the beginning of March in these places! It won't be that extreme downstream, but it will clearly be much below average for most east of the Rockies for a few days next week.
The countdown to spring is underway, but there's going to be plenty of cold and snow in the days ahead from the Dakotas to the mid-Atlantic and New England.
The polar vortex will roll south-southeastward over the next three days, descending upon the Great Lakes and Northeast this weekend with the coldest air mass of the winter season.
A wave of low pressure will clip the mid-Atlantic coast late tomorrow and tomorrow night, possibly resulting in some snow. A stronger storm could bring snow to parts of the East next week.
A deepening storm coming out of the Rockies and head for the Great Lakes will dump heavy snow from Colorado to Wisconsin and Minnesota, while springlike warmth will fuel severe thunderstorms from the Ohio Valley to the Gulf Coast.
Despite the historical snowfall from the Blizzard of 2016, a warm surge later this weekend and early next week will wipe out most of the snow that fell during the storm.
A major nor'easter will bring heavy, wind-blown snow through the mid-Atlantic region later Friday through Saturday, sparing much of New England of its fury.