Monday, 11:30 a.m.
Another day, another storm. This one really deepened over the weekend and took some surprising twists and turns along the way from my vantage point. It developed in the northeast Pacific last Thursday night and Friday, roared across Vancouver and through Washington later Friday into Friday evening, then dove into the Rockies Saturday.
The dive turned out to be stronger than I expected, allowing the system to dig into the southern Rockies and roll underneath Colorado. That allowed more moisture to be thrust back into eastern parts of the state, blanketing parts of the state with 1 to 2 feet of snow. That snow has extended down into New Mexico and the Texas Panhandle, with a powerful low now about to roll across the Red River Valley through southeastern Oklahoma and then Arkansas.
North of the low, there's enough cold air to generate a lot of snow in parts of Oklahoma and southern Kansas. The storm is intense enough that it will wrap warm air around it to its north side for a time this afternoon and tonight, which will limit the snow fall potential in western Missouri and southernmost Iowa as well as Illinois, but what snow does fall will be blown around by strong winds on the western flank of the storm.
The warm air will bring rain, and maybe even some thunderstorms, into much of the Ohio Valley. The thunderstorms will be stronger along the Gulf Coast late this afternoon and tonight, where there is a ready made supply of humid air with dew points in the 60s. The thunderstorms will generate enough rain over southeastern Mississippi, southern Alabama, the Florida Panhandle and parts of Georgia to warrant concerns for flooding given how much rain has fallen on much of this area already.
Figuring out the precipitation tomorrow afternoon into Wednesday from the interior mid-Atlantic into New England is going to be a challenge. Yes, warm air is going to charge northward ahead of the storm. By the same token, the air is initially very dry, so as the precipitation begins to fall, the atmosphere will cool somewhat, and that can allow snow and sleet to reach the ground into parts of West Virginia and westernmost Virginia for a time, though that will be much more of a concern farther north across Pennsylvania and over into New England.
The latest NAM model forecast appears to be a tad colder and farther south with the track of the low, which would suggest more snow than other forms of precipitation from about I-80 on north, and from Poughkeepsie over to Boston. That's consistent with the European model, which, right now, is the coldest and farthest south of any model. Here's the NAM surface forecast for Tuesday night:
My take is that for a while, precipitation intensity and elevation will determine what falls in any given location. The stronger the upward motion, the stronger the cooling, the heavier the precipitation and the more likely it is to snow, especially in the higher elevations. I fully expect to see some wild variations in snow depth over relatively short distances when all is said and done!
The mild air will linger in the East through Wednesday, but at the same time, the chill will grow in the Plains and Mississippi Valley into the Ohio and Tennessee valleys behind it. Thankfully, the rest of the week looks relatively quiet, good news for the central Plains after getting pummeled by two storms inside of a week.
The Northwest isn't out of the wood just yet, but the action will be shifting north with time. There's another system bringing wind and some lingering rain showers through Washington today. A weaker one skirts the area tomorrow night and Wednesday, more aimed at Vancouver and British Columbia. Then, as the upper-level ridge steadily builds throughout the week, not only will it dry out in the region, but most of the West will turn warmer. Here's what that ridge might look like Friday:
In keeping with that, here are the projected temperature anomalies for Saturday:
However, much like the old playground see-saw, if one end goes up, there has to be opposing reaction on the other end. In this case, the downstream trough and the bottoming out of temperatures from the central and southern Plains on East. The pattern will settle down for a time, but east of the Rockies, it is not going to be warm for a while as we get ready to step into March.
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.