Friday, 11:35 a.m.
The past couple of days became a blur for me as I succumbed to the intestinal bug. Out of nowhere, I went quickly downhill Wednesday morning, leaving work early. I've returned today, better, but not quite yet at full capacity. I value my good health that much more today!
It has turned noticeably milder of the past couple of days, and the mild weather will hang on into the weekend in the East. This is helping to peel back the snow cover in Virginia and Maryland and reducing the snow pack farther north. There's still quite a bit of snow from New England and Pennsylvania on north and west, and with the impending arctic chill next week, what remains won't be going anywhere any time soon.
The powerful storm lifting northward across the northern Great Lakes into southern Ontario has helped to spark a lot of severe weather over the past 24 hours. Just look at the reports logged from 12z Thursday to 12z Friday:
We're not quite done with severe weather today, as the cold front arcing from this storm is now swinging over the Appalachians through Virginia and the Carolinas, igniting a few more strong thunderstorms along the way. And that's not really much of shock, given how high the dewpoints are charging northward ahead of the cold front.
The air immediately behind this front is not terribly cold. In fact, with the storm itself rolling up into northern Ontario to near James Bay tomorrow, the jet stream flow underneath it is more westerly. Look at the 12z Feb. 21 NAM 500mb forecast for tomorrow evening:
That means tomorrow will be near to still a little above normal in the Ohio and Tennessee valleys, and even more so in New England and the mid-Atlantic states, especially where the snow cover is erased.
However, the cold is coming.
A weak cold front will slide across the Great Lakes into the Ohio Valley and Northeast tomorrow night into Sunday morning. There may be a little snow with this feature, but the front may well become the focal point for a wave of low pressure to form along the front later Sunday and Sunday night. That should lead to a period of snow, or rain changing to snow, from Kentucky and West Virginia into southern New England. Snow amounts won't be all that impressive, but it is coming right on the heels of a brief mild period, and it's yet more snow in an already exceptional season of snow.
Behind the wave, the massive cold expands farther south and east on Monday. Look at the GFS anomalies for Monday:
As cold as it gets Monday, the worst is still to come. High pressure will build into Montana and the western Dakotas later Monday and Monday night, pushing arctic air down into the northern and eastern Rockies. This will spit out an upper-level disturbance across the Plains, one that will dart quickly across the country Tuesday and Tuesday night. It appears as if this will be followed quickly by a somewhat stronger wave that should get to the East Coast late Wednesday and early Wednesday night. This latter wave is the one we've been most concerned about for more than a week, one that could bring a significant snow to portions of the mid-Atlantic and Northeast. The details of that are still to be ferreted out, but one thing is certain: behind that feature, the core of the cold is unleashed. Here's the GFS anomaly forecast for next Friday:
That's as brutal of a cold air mass as you will ever see at the end of February. It will linger into the start of March before there is an ever-so-brief interruption in the cold. Spring may be 27 days away, but it will be a long 27 days.
Two systems will delay the onset of warm weather in the Ohio Valley and the East over the next week or so, but then it should get warm all across the country heading into the Memorial Day weekend.
A turn to much colder air over the Northeast and mid-Atlantic states will set the stage for a rain and snow storm later this weekend before it turns much warmer later next week.
It's warm now, but will turn much colder this weekend, with a storm threat later Saturday into Sunday. Warmth will return by the second half of next week.
Though it is cold now east of the Mississippi, with a couple of opportunities for snow into the weekend, a blast of warmth is due for much of the country east of the Rockies next week.
Warm air will once again surge eastward from the Plains to the East Coast this weekend and early next week. A strong storm next Tuesday and Wednesday will then be followed by colder air later next week.
A storm in Southeast Texas will generate severe thunderstorms this afternoon and tonight, and some wet snow on its western flank as it heads into the Ohio Valley tomorrow.