Severe WX Severe Weather Threat 2/27/17-3/2/17

[MichelleH]

Reports of cars blown off I-65 near Cool Springs, TN!

 

[Equus]

60% wind probs are pretty eye-popping. Not too often you see 60% anything (not sure what it'd take to see 60% tornado probs). 45% for us here. At the office until ~12:30 and then heading home after a lunch meeting.

April 7 2006 had a 60% TOR around the TN/MS/AL border for a couple outlooks, I think only time they ever went that high.

Very scary storms last night for sure. No doubt the most intense tornadoes of 2017 thus far.

 

[xJownage]

April 7 2006 had a 60% TOR around the TN/MS/AL border for a couple outlooks, I think only time they ever went that high.

Very scary storms last night for sure. No doubt the most intense tornadoes of 2017 thus far.

good memory, although the day was comparatively a bust. It was a decent outbreak, but nothing worth a 60% hatched for tornadoes (4/27/11 was 45%, by comparison).

 

[xJownage]

As for today's outlook, I've never seen the NWS shape an outlook based on such a small swath of strong wind for so long; it looks like a derecho prediction, basically.

 

[Equus]

Yep, except for Gallatin the April 7 event was rather benign. I recall staying up late expecting the apocalypse and getting a mild squall line with scattered brief touchdowns.

 

[Bama Ravens]

So the HRRR now has discrete cells forming ahead of the main line in north-central AL

 

[MichelleH]

So the HRRR now has discrete cells forming ahead of the main line in north-central AL

Not good at all...

 

[Kory]

So the HRRR now has discrete cells forming ahead of the main line in north-central AL

The problem continues to be unidirectional flow. Discrete cells might have a downdraft/hail component but anything more is VERY low. You can see the flow in the lowest 1km is NOT conducive for tornadic storms at all.

 

[rolltide_130]

More damage out of Perryville.. oh boy.

 

[Lori]

 

[warneagle]

More damage out of Perryville.. oh boy.

Wow, could be talking about an EF3-EF4 rating on this one when all is said and done. Haven't seen many damage photos from the affected parts of IL yet.

It sure was eerie how closely that supercell paralleled the path of the Tri-State Tornado.

 

[gangstonc]

http://www.spc.noaa.gov/products/md/md0241.html

Tornado watch likely soon for N AL, N MS, NW GA, and SE TN.

 

[xJownage]

Wow, could be talking about an EF3-EF4 rating on this one when all is said and done. Haven't seen many damage photos from the affected parts of IL yet.

It sure was eerie how closely that supercell paralleled the path of the Tri-State Tornado.

That was literally the first thing I said when it touched down and started racing a large tornado across the area. Thankfully it wasn't as long; a nocturnal modern tri-state tornado would be nothing short of absolutely devastating.

 

[MichelleH]

New tornado watch coming soon for North Alabama, North Mississippi, South-Central Tennessee and Northwest Georgia.

http://www.spc.noaa.gov/products/md/md0241.html

 

[Equus]

Those cells in MS do look a bit concerning.

 

[Equus]

And looks like they just pulled the enhanced further into AL.

Also yikes

 

[Bama Ravens]

Yep, they've pulled much further south.

 

[Kory]

I'm noticing mesoscale models are under forecasting the low level helicity values. They're being driven more by speed shear (rapid increase in velocity with height) than directional shear (veering of the winds with altitude). Model progs were <200 m2/s2 0-1 km helicity....they're sitting at 300-350 m2/s2. Usually SW surface winds don't really work....but this argues something else....

 

[Bama Ravens]

It really seems like SPC has ramped up on the tornado threat over north-central Alabama. Not that it is a huge threat.

 

[WesL]