Tuesday, 11:35 a.m.
If you look at the weather across the country right now, there's little indication of what's about to unfold across much of the country. Indeed, there's not much wintry weather at the moment, with just a couple of pockets of snow in Montana as I type this. Look at the current visible satellite image:
There are a lot of clouds from central Pennsylvania down through Virginia into the Carolinas, but the rain is not impressive. There's a lot of dry air west of the Appalachians and almost as much over New England and the western Atlantic that's being drawn inland and eaten away big time at the current cloud cover.
Farther south, there are thunderstorms over the northwest Gulf, and those, believe it or not, are tied with the feature we'll be tracking for potential surface low development late this week over or around Florida. We're seeing some thunderstorms with an upper-level disturbance in Michigan. There are some clouds in Wyoming, and a wave of low pressure passing just north of International Falls, Minn., has pulled a healthy cold front through North Dakota into northern Minnesota.
Aside from all those rather minor weather events, though, it's pretty doggone quiet. For now.
Look at the 500mb forecast for this evening:
An upper-level ridge is in the process of strengthening over southeastern Ontario and Quebec. You see that upper-level low over the northwest Gulf and the feature driving the surface storm by northern Minnesota. It's being driven northwest because of the building ridge out in front of it, and that, in turn, means the feature digging into the Rockies is forced to go around the disturbance ahead of it. That means it digs even more, and in the process it will pull much colder air southward out of western Canada yet again.
All that adds up to a rapidly developing snowstorm over the Rockies late tonight and tonight into tomorrow. Initially, it will largely be over Wyoming, but with time it will spread into northern and eastern Colorado. Then out into northern and western Kansas and parts of Nebraska. There may be parts of Colorado that wind up with a foot of snow, while the Denver metropolitan area picks up at least 3-6 inches of heavy, wet snow. Welcome to May!
Oh, and it won't be done then, either. With temperatures in the 70s and 80s ahead of the front and dew points charging up to 60 or better along the Mississippi Valley, there's a strengthening temperature contrast from one side of the front to the other. As an upper-level low gradually forms tomorrow night and Thursday, it will act to pull that warm, moist air and wrap it back into the cold air to the west, and that's going to mean some snow.
That band of snow won't necessarily be wide, but in the middle of it, there may be a lot of heavy, wet, branch-breaking snow; 6 to 12 inches seems like a reasonable guesstimate right now, which in and of itself is highly unreasonable! There could be two bursts of snow, with an initial one moving out across Nebraska and southeastern South Dakota into southwestern Minnesota. A second one is liable to set up tomorrow night and Thursday farther south and east, impacting areas from Kansas to eastern Minnesota and northwestern Wisconsin.
And that's just the snow potential. There is likely to be a lot of rain farther east and southeast, and if that falls over the middle Mississippi watershed areas, it may well mean flooding, perhaps widespread flooding. Several inches of rain seems to be in order in these areas over an extended period of time, though much of it will end up falling over a two-day period.
Lastly, there is that aforementioned upper-level low along the Gulf Coast. While the prospect of a subtropical low getting well organized over or near Florida Friday and Saturday is diminishing, there's still going to be some wet weather from the central Gulf Coast region eastward into Florida for the rest of the week into the weekend. Overall, that's probably very good news as the region continues to recover from a long-term drought.
And that doesn't even include the record heat over parts of California, Arizona and Nevada or the growing area of delightful spring weather over the Northeast from today and lasting through the weekend.
The weather is about to go on a wild ride, one that won't stop until sometime this weekend.
In the wake of the feature bringing snow through the mid-Atlantic and southern New England today, there will be a nice little period of cold and quiet weather for most of the country until the next storm begins to take shape over the southern Plains and Mississippi Valley late Friday into Friday night.
Winter doesn't officially begin until Dec. 21, but there's plenty of evidence of winter already fully in force around the country. The rest of fall will largely be cold in much of the nation before it tries to moderate later next week.
One fast-moving storm will dump snow, ice and rain over a wide area from Arkansas to southern New England this afternoon and tonight. Another will follow for later in the weekend.
Two separate features will zip across the eastern half of the country by the start of the weekend, generating rain, thunderstorms, ice and snow before it quickly dries out to start the weekend.
Three storms over the next week will dump snow and ice over a large portion of the country, and with frigid arctic air firmly in place around the country, it would appear winter is here to stay.
A bitterly cold air mass is burrowing into the Northwest and northern Rockies today. It will continue to press south and east the rest of the week, only to be slowed trying to reach the East Coast.