Heads Up: Dangerous Storm Eastern U.S. This Weekend. Vermont Effects Included

Precipitation forecast map for th next seven days. Most of the
precipitation you see is with the forecast big stom this weekend.
Purple shades, as in over Vermont, depict about 1.5 inches of
rain or melted snow and ice. That huge area of bright
red is two to seven inches of rain, so you
see a big area that's under a flood risk. 

I usually don't like to hype storms too far in advance. As most of us know, computer models more than a few days out can be unreliable.

This time, though, I'm going into hype mode, at least to an extent. The computer models have been consistent in saying some rough weather is due in the eastern half of the nation Friday through Sunday.

It's rare to see the Storm Prediction Center highlighting a risk for tornadoes and severe storms five or six days in advance.

But that's what they're saying about a zone from eastern Texas and across the Gulf Coast states Friday and Saturday with this system.

The devil is always in the details, so we won't know how extensive this severe outbreak will actually turn out to be. But there is the risk, at least of some pretty significant tornadoes and high winds across the South Friday and Saturday.

Likewise, this storm is going to have a LOT of moisture to work with.  Parts of the South, and Tennesee and Ohio valleys have been quite wet of late, and early predictions are already touting two to six inches of rain with this system in that region.  Some flooding is already ongoing, so it will only get worse this weekend. 

This storm will likely get some of its power from a very strong Bermuda-high like ridge of high pressure off the East Coast.  That will probably create some record high temperatures in the coming days along the Eastern Seaboard.

The arrangement of that ridge of high pressure will bring quite a lot of moisture inland off the Atlantic and the Gulf of Mexico.

Meanwhile, a strong dip in the jet stream, and a strong jet stream aloft, will provide plenty of energy and instability for heavy rain, thunderstorms and possible southern tornadoes. And winter cold air from the west will just add a clash of air masses to wring the heavy precipitation as the system heads northeastward.

You'll very likely hear about this storm in the news in the upcoming days and through the weekend. Unfortunately, it could easily prove deadly and destructive in the South.

VERMONT IMPACTS

The storm will inevitably head northeastward into New England. For us here in Vermont, something nasty looks like a near certainty over the weekend, but what form that nastiness would take is still anybody's guess at this point.

We know there's a good potential for precipitation to be heavy.  Perhaps one to two inches of liquid equivalent, which is a good thumping for mid-winter, which tends to be drier.

But will it rain? Snow? Freezing rain? Locusts?  All of the above?  For now, I'm going with all of the above, except for the locusts. I'm pretty sure we won't get locusts.

We won't know exactly what will happen until nearly the last minute. But I'd start planning for difficult travel on Sunday.

We could easily have another messy ice deal like we did back on December 30, though the precipitation this time looks like it might be heavier.

It all depends upon when cold air from the northwest plays out.

Here's how the National Weather Service in South Burlington thinks it'll play out.  Remember, results may vary, and forecasts will change. Stay tuned for updates.

We'll start out with a brief shot of Arctic air Wednesday afternoon through Thursday. Thursday will be the first colder than normal day around Vermont since December 21.  Lows will be near zero, with highs in the teens to near 20.

Yeah, that's cold, but no great shakes for a Vermont January day.

Then the fun starts. Temperatures will start rising Thursday night as winds pick up from the south.  A piece of the storm will draw a warm front through, causing some light mixed precipitation going over to some light rain Friday.

The real problem Thursday night and Friday will be strong winds, created by the contrast between that vigorous ridge off the East Coast and storminess to the west.

It'll continue to warm up Friday into Saturday, but how warm it gets depends upon when a cold front arrives. Could be record warm, could be just kinda warm. We'll see.

Here's where it gets really complicated. Chilly high pressure will come across the northern Great Lakes and into Ontario and southern Quebec. That would feed cold air in the lower levels of the atmosphere towards us here in Vermont.

Meanwhile, warm, wet air will glide northward up above that chilly air.

How cold will it get and how far south will the chilly air make it?  If the answer is very little and it stays warm, we'd get a lot of rain and we'd have a flooding risk.

If mostly low level cold air comes in but it stays warm aloft, that sets us up for a bunch of freezing rain and sleet.

If the cold air blasts in, we get a lot of snow.

Take your pick, because nobody is yet sure which scenario would play out, and where in Vermont different types of precipitation sets up.

Here's a worst case scenario for you, though. In their forecast discussion, the National Weather Service in South Burlington compares the overall weather setup this weekend to March 6-7, 2011.

On that occasion, we got a bunch of rain and melting snow, which led to some flooding. Then, the colder air came in, changing rain to snow, especially across the north. There was a LOT of snow with that March, 2011 storm. 

Burlington got 25.8 inches of snow, which was up until that time the greatest March snowstorm on record. (Later usurped by the Pi Day Blizzard of March 14, 2017).

Most of northern Vermont got around two feet of snow in that 2011 event.

I'm not saying history will repeat itself this weekend. I'm guessing it won't. But as I said at the start, this is a head's up.