Monday, 11:05 a.m.
We have reached the bottom of the temperature curve. From now until late July, the average temperature will be on the rise. We're more than a month past the winter solstice, with 10 hours of daylight now at hand, and gaining two to three minutes a day in the mid latitudes. Groundhog Day is Saturday. And right on cue, here comes a robust warmup that will push temperatures to record levels.
A storm will come out of the Rockies late tonight and tomorrow morning, then cut for the Great Lakes tomorrow night and Wednesday morning. In an odd sort of way, I had the right idea of all the arctic air, but dry, then a cutting storm bringing more rain than anything else! It just turned out to be four to five days later than I had expected. Instead, the storm late last week was squashed to the south, and the cold held on through the weekend.
Today, however, it is being beaten back. It's pretty much gone from the Midwest, though there may still be some issues tonight and tomorrow morning with freezing rain as the next storm approaches. Most of the Ohio Valley is now in the 40s, as is the case over southern Michigan. And this is only with a weak wave of low pressure moving across the Great Lakes. Here's the 10 a.m. surface pressure analysis:
This wave of low pressure, though, is not strong enough to erase all of the arctic air in the low levels of the atmosphere across the interior mid-Atlantic and Northeast this afternoon and tonight. There the low-level cold will hang on for dear life tonight into tomorrow. In fact, here's the NAM surface pressure forecast for tomorrow morning, showing that wave of low pressure sliding east-southeastward away from Cape Cod:
In most places away from the coast, temperatures will either stop rising overnight, or perhaps even fall a couple of degrees. And with the stronger storm still gelling tomorrow across the Plains, it will take some time before a much stronger southerly wind can scour out the last of the low-level chilly air in the mid-Atlantic and Northeast. However, go it will tomorrow night and Wednesday.
Another thing that is fairly typical of a springlike storm is severe weather. And it's not just a small area that could be impacted by strong thunderstorms, but potentially more than a dozen states. Tomorrow, that threat stretches from central and eastern Texas to the middle and lower Mississippi Valley, spreading across the Ohio and Tennessee valleys into the Deep South tomorrow night into Wednesday morning, then east of the Appalachians later Wednesday and early Wednesday night.
One thing this warmth will do is wipe out the snow and ice of the next 24 hours, and a whole lot more. Here's what the snowcover chart looked like early today:
The warmth will linger into early Thursday over eastern New England, but then it'll be over. The taste of spring will be ever so fleeting, as the first of what will ultimately be several arctic waves blasts its way through the Midwest and across the Great Lakes and Ohio Valley into New England and the mid-Atlantic states.
One interesting twist on this is that the threat of a freeze in Florida is fading. The first shot Thursday into Friday just won't get that far south. There will be a few more waves of arctic air to follow this weekend and through next week, if not beyond, and I guess there is still a risk of one of them being strong enough to make it that far south. Given the trend of the past few weeks, though, the time of year, and the lack of snow cover across most of the Ohio and Tennessee valleys into the mid-Atlantic states, it's hard to see any subsequent arctic push making it that far south in the first week or two of February. I'm not saying it can't happen, but rather that given all of the things on the table right now, it's hard to see it happening.
A deep upper-level trough of low pressure is caught in between two strong upper-level ridges, locking cool weather into Plains to the Appalachians and beyond.
A much cooler air mass will expand from the northern Plains this weekend to the Deep South and into the East by Tuesday, pushing temperatures much below normal.
Intense heat and oppressive humidity surging out of the central Plains will cause severe weather from the Midwest to the Ohio Valley in the next 72 hours, followed by much cooler weather next week.
Despite the heat and humidity in the East today and a surge of intense heat and humidity coming out of the central and southern Plains for a brief period of time, cool air will dominate the pattern through the end of July from the Plains to the Appalachians.
A pattern of extremes is once again unfolding across the country over the next week, with two shots of cool air interspersed with intense heat.
Despite the heat over the central and southern Rockies this week, an amplified pattern means cool air will dominate in much of the country for the rest of July.