Tuesday, 11:55 a.m.
The first storm of the week is long gone. Colder air has bled southward into northern Virginia, but its progress has come to a halt. The storm developing in the southern Plains is already sending a lot of high-level moisture across the Ohio and Tennessee valleys into the mid-Atlantic states, and precipitation has been rapidly expanding across the central Plains to the mid-Mississippi Valley. A look at satellite-radar composite as of 11 a.m.:
There is no downstream blocking over the Atlantic, so this storm will do its best to cut toward the Great Lakes, and it will have modest success. The surface low center won't make it all the way to Lake Erie in the end, but the low aloft will get awfully close. Look at the 12z Feb. 4 NAM 850mb forecast of heights and temperatures for tomorrow morning:
The warmth aloft will follow the low center aloft. In fact, if you were to more closely examine the thermal structure of the atmosphere tonight into tomorrow morning, the warmest level will actually be higher up than the 850mb level, and it will be plenty warm enough to change snow to sleet deep into the heart of Pennsylvania as well as across southern New England. This will limit snow accumulations across the southern half of Pennsylvania, the lower Hudson Valley and much of Connecticut, Rhode Island and southeastern Massachusetts, perhaps all the way up to the Mass Pike.
Therefore, the heaviest snow will likely be in the northern tier of Pennsylvania and the southern tier of New York over to much of Massachusetts, southern Vermont, southern New Hampshire and coastal Maine, where a solid 6-12 inches will accumulate, with locally 15 inches.
Once this storm is gone, cold air will dominate the middle of the country the rest of the week, and we'll begin to brace for storm three, due sometime this weekend. More on that storm tomorrow.
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.