Tuesday, 11:59 a.m.
The weather over the past couple of days has been nice and quiet. There were just a handful of reports of severe weather in the past 24 hours; most of those reports were hail-bearing thunderstorms affecting southern Virginia. This afternoon and tonight will also be more or less devoid of severe weather around the country, as the entire southern half of the country is just plain dry, and pretty sunny and very warm, too. We're starting to see some low-level moisture coming to plain in parts of the western Gulf Coast region and on into Texas, but it's still pretty shallow. For now, it's just starting the process of moistening up the atmosphere to the point where showers and thunderstorms will become much more widespread - and expected.
What we do have is a lot of hot air! Look at the 12z May 6 NAM 850 temperature forecast for this evening:
That 25C air over Kansas, Oklahoma and West Texas is high enough to boost temperatures past 100 this afternoon, especially if the low levels are dry.
While the air right now is dry just off the deck, it is starting to moisten up, and this process will continue tonight and tomorrow. By then, the upper-level low rolling through California and Nevada will be working its way through the southern Rockies, causing the surface pressure to lower over the eastern Rockies. As the upper-level low approaches the eastern Rockies, the air aloft will begin to cool, and the whole column will rapidly begin to destabilize. With all of that heat around on the Plains, and a gradually increasing pool of moisture in the lower levels, it will become simply a matter of time before strong thunderstorms erupt. It may not be during the day tomorrow, but almost assuredly after dark. Look at the SPC outlook for tomorrow and tomorrow night:
This gets us to Thursday, when the surface low and its attendant upper-level low open up and lift out to the northeast toward Minnesota. Additional strong to severe thunderstorms are likely with and ahead of the cold front attached to the storm. This will propel the front into the Midwest and across the Plains, but a second upper-level disturbance coming through the Rockies will ignite more showers and thunderstorms later Thursday and Thursday night from Kansas down to Texas. This large area of active weather will then march eastward toward the Mississippi Valley, then into the Ohio and Tennessee valleys late Thursday night and Friday. And that sets the table for a wet start to the weekend in the East. Here's the forecast of total precipitation from tomorrow morning at 12z through 12z Sunday from the European model:
That will set up two areas of heavy rain, one in the northern Plains and parts of the Midwest, and another from central and east Texas to Alabama and up the spine of the Appalachians. Rain could easily be heavy enough to cause flooding in addition to the threat of severe weather.
So, while it may be quiet now, a stormy period is straight ahead in the weather. Sounds a lot like spring!!!!!
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.
A major spring storm will move from Texas tonight to the eastern Great Lakes Wednesday night, producing heavy rain and severe thunderstorms, with a swath of heavy, wet snow on its western flank.