Dangerous Tornado Outbreak South; Record Warmth, Thunder, Flood Watch Here In Vermont

Area in pink is at the highest risk of tornadoes today some
strong and long lasting. Surrounding area in red is at 
almost as high a risk. 

A little over a week ago, Mississippi and Alabama experienced a relatively rare "high risk" day for tornadoes, which is the most dangerous situation you can get for predicted severe weather. 

The storm causing the danger in the South will affect Vermont, but of course not with tornadoes.

We expect record warmth, a good dose of rain, some wind, maybe some flooding, maybe some thunderstorms. More on that in a bit.

SOUTHERN TORNADOES

Although a total of 49 tornadoes caused a lot of destruction in mostly rural parts of Mississippi and Alabama on March 17, there were no fatalities. 

The worst storms missed the cities, and warnings in advance of the tornadoes were excellent. With all that, they dodged a bullet.

Will they today?

None of those March 17 tornadoes were at the upper end of the tornado strength scale.  The strongest tornadoes last week on a strength scale labeled EF that range from EF0 to EF5. The strongest tornadoes last week were at level EF2, with top winds of 135 mph. The vast majority of all tornadoes in the United States are at EF2 strength or less.  

There is, unfortunately, a good chance of very strong tornadoes today. This will hit in basically the same areas that were under the gun a week ago.  

Conditions almost couldn't be more perfect for intense, long lasting tornadoes, especially in the northern halves of Mississippi and Alabama and the western half of Tennessee.  This includes the cities of Tupelo, Jackson, Memphis, Nashville and Birmingham.

Stronger tornadoes in a worst case scenario can winds over 200 mph and level almost everything in their path.  Most tornadoes are on the ground for only a few minutes, but long-tracked tornadoes like the ones possible today could keep grinding their way through towns and countrysides for more than an hour or even several hours. 

Rotating supercell thunderstorms are expected to rapidly form in central Mississippi this afternoon and move northeast.  Humid air, a lot of instability and winds changing direction and speed with height along the path of these storms bodes poorly for this region. 

As was the case last time, many areas under the greatest threat have a high degree of poverty, so many people might not have the wherewithal to hear or act on warnings.  Substandard housing and a great many vulnerable mobile homes adds to the danger. 

The mess of tornadic storms will eventually congeal into a squall line that will head toward the Ohio Valley tonight with strong wind gusts and a few more possible tornadoes.

VERMONT IMPACTS

In the last southern tornado outbreak, the parent storm causing the havoc entirely missed us, keeping us dry. 

Not this time. As I've said before, it's excellent that we're getting a needed slug of rain, there are a few potential downsides. 

Before the storm, warm air is surging into our area. Temperatures were already in the 50s for many of us as dawn broke this morning. Despite some increasing clouds this afternoon, temperatures will be in record breaking territory this afternoon.  Several places will hit the low 70s. 

Records for the date are likely to be broken in Burlington, Montpelier and other cities and towns around the region.

The first wave of rain will come through within a few hours either side of dawn tomorrow. In Vermont especially, the rain will move off to the north and some breaks of sun are possible as temperatures go well into the 60s, and possibly near 70 again if there's enough sun.

That potential sunshine will make the air more unstable as the storm's cold front approaches. At this point there looks like a band of showers and early season thunderstorms will come through.  I suppose a few storms could have some gusty winds and even small hail, but it doesn't look like there will be anything severe.

It's awfully early in the season for that sort of thing anyway. 

The two bouts of rain, combined with the melting snow in the mountains, has prompted that flood watch for much of the region.  Many area rivers will end up near bankfull by Friday night or Saturday morning, with minor flooding possible along these rivers.  

It'll turn sharply colder Friday night with even some snowflakes in the air in places, but this won't be anything odd for March.

I won't get into that second storm expected Sunday and Monday in this post, but certainly expect some variable weather coming up with that system, and beyond.