2020-04-12 EVENT: TX/AR/LA/TN/KY/MS/AL/GA/FL

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Jesse Risley

Staff member
Apr 12, 2006
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Since this event is finally coming into range of the NAM, it's time to start a thread highlighting the possibility of a substantial severe weather threat for much of Dixieland on Easter Sunday. The GFS has heretofore been more progressive than the ECMWF, so something akin to a blend between the ECMWF and the NAM will probably be a more reasonable solution.

Models have been depicting a closed low, associated with the southern stream of a broader longwave pattern of energy traversing over the CONUS, kicking out of the Baja region this weekend, with the stout southern shortwave moving out of the southern Plains and taking on a more negative tilt as it pushes into the mid-Mississippi River valley. A surface cyclone should move out of the eastern Red River valley and deepen as it moves towards W TN and then the Ohio River valley by early Sunday evening. The northward extent of the warm sector is still somewhat in question, which will help determine the exact region of optimal instability, but strong deep layer shear should be juxtaposed with ample warm sector instability - owed partially to rich Gulf moisture - across the eastern fringes of the Western Gulf Coastal Plains, the Lower Mississippi Alluvial Valley, and the Eastern Gulf Coastal Plains region, perhaps even moving well north of I-20 by Saturday evening.

Forecast deep layer vertical share profiles, owed partially to strong and increasingly favorable H85 wind profiles, certainly favor discrete supercells, with substantial 0-1 km SRH, favorable LCLs and plenteous instability yielding the possibility of some significant tornadoes, particularly if storms remain discrete, though all modes of severe weather are possible. Early day EML should help to suppress convection in the warm sector until convection redevelops INVO a surface trough that will likely incite the primary, deep convective activity that has the potential to be the most volatile. With otherwise favorable deep layer vertical shear and ample speed shear in place, the real factor to monitor will be the size and northward extent of the warm sector and how any ancillary convection otherwise associated with this dynamic system impacts that, as well as the final placement of the warm front and the most favorable Theta-e axis. Some of the forecast soundings indicate the potential for tornadic activity to continue eastward well after dark. Timing and placement of certain synoptic features are likely to vacillate between now and Sunday afternoon as RAOB systems better sample the energy currently out west.
 
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Patrick K

Enthusiast
May 2, 2019
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I was too chicken to make this thread yesterday afternoon before the CAMs were in range. My main concern yesterday was lack of capping across the warm sector, causing the usual crapvection and preventing northward transport of sufficient dewpoints. That still appears to be a potential issue, but unless I'm mistaken, both GFS and Euro are now showing an EML further westward, closer to the developing low.

There's a lot to like about this setup, with agreement on the shortwave having a neutral-ish tilt, nearly textbook wind profiles, with strong west-southwesterly flow atop south-southeasterly flow, sufficient instability and classic sickle-shaped hodos. In my mind, and without a whole lot of guidance from the CAMs, there still appears to be an issue with timing. It seems like convection could pop off too early and wash out the warm sector before the most favorable environment is in place. NAM12k seems to imply another round of convective initiation around 21Z with a likely broken band of discrete/semi-discrete supercells moving ENE into AL before it grows upscale, but will parameters be as strong in the wake of earlier storms? As usual, we'll have to wait and see.

I would target the area around Jackson, MS on this Easter morning.
 
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Jesse Risley

Staff member
Apr 12, 2006
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Macomb, IL
www.tornadoguys.com
It seems like convection could pop off too early and wash out the warm sector before the most favorable environment is in place. NAM12k seems to imply another round of convective initiation around 21Z with a likely broken band of discrete/semi-discrete supercells moving ENE into AL before it grows upscale, but will parameters be as strong in the wake of earlier storms? As usual, we'll have to wait and see.

I would target the area around Jackson, MS on this Easter morning.
I didn't get into all of the finer mesoscale details since we are still a few days out, but I did notice that the newer runs of the NAM had a subtle little vorticity perturbation that comes out of east Texas into Louisiana and kicks off some precipitation that lingers into the morning, particularly along and north of I-20, and that is timed ahead of the main shortwave energy. That could definitely be a factor in holding the warm front further south. That early day convection will also need to be watched in terms of timing and removal, especially where air mass recovery and lapse rates are concerned. Similar setups have had stuff earlier in the day that posed no issue, but as everyone knows it's all about timing and placement. It is honing in on a fairly narrow and concentrated zone of better instability that may be more concentrated that the aereal extent of some of the other more notable "outbreaks," although their definitely is plenty of energy for this event to keep tornadic potential going even overnight as you get into Georgia.
 

SBonesteel

Enthusiast
Apr 11, 2020
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Ann Arbor, MI
It's going to be a very tough chase day. Storm motions look fast, you won't have the ability to simply just drop south and get out of the way because the trailing cell will likely still get you. If you plan on spotting, you'll be best off picking your spot of interest and letting it come to you. If the setup verifies, which still appears conditional in some aspects, a good number of cells will spin something up or try to.
 
Jun 1, 2008
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Chattanooga, TN
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Event is coming into focus as the MCS lifts north into Tennessee. Outflow is left in Alabama and somewhat Mississippi. It's merging with the WF in Miss. If the OFB can remain separate in Alabama I think that's big trouble. CAMs have been a debacle, but it's now surface and satellite time.

Storm motions will be fast. Cells will still be sloppy. However I believe a virtual target exists in Alabama. I'm not chasing. As the next jet streak comes out a surface wave may develop in Mississippi and track into Tenn. This is separate from the synoptic low. East of that wave, perhaps in Alabama on the outflow, is my area of interest this afternoon.
 
Mar 3, 2012
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Hillsdale, MI
Is it odd that the earlier tornado warning was a PDS, while this new one isn't? I'm not an expert by any means, but this new area seems to be in at least as much trouble as Mississippi and Louisiana was earlier.

Edit: Maybe I wasn't paying attention too well. But what just happened in Bassfield, MS looks to be horrifying. Debris lofted at least 20,000 ft high, heard higher numbers as well. Looks like an enormously large, destructive long track tornado is ongoing and just went through the hart of Bassfield.
 
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Mar 3, 2012
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Hillsdale, MI
To add to the trouble, the one behind it is starting to get its act together. It may go a bit north of the leading supercell, but not by much. Looks like a lot of residential areas are taking on the full brunt of this.
 
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Aug 18, 2018
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Novi, MI
I’m getting word that a chaser in southern MS crossed a median and is driving on the wrong side of a highway to chase one of the violent tornadoes ongoing. I thought storm chasers were supposed to be “saving lives” and were deemed “essential.” This is pure stupidity. Putting additional lives at risk to chase a storm?

This is supposedly a screenshot from his Twitch live-stream.

8DF35DA3-9D4D-4B43-B566-C3B7F77705BB.jpeg
 
Jul 16, 2013
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Joplin, MO
I’m getting word that a chaser in southern MS crossed a median and is driving on the wrong side of a highway to chase one of the violent tornadoes ongoing. I thought storm chasers were supposed to be “saving lives” and were deemed “essential.” This is pure stupidity. Putting additional lives at risk to chase a storm?

This is supposedly a screenshot from his Twitch live-stream.

View attachment 20290
I've watched a few live feeds of a well known chaser today, I've lost count the number of stop signs he blew through and the number of times he made illegal passes. All in the name of "saving lives" during a pandemic. Hopefully his reckless, irresponsible driving won't result in an accident and having to pull resources (first resonders) away from damage areas where they're truly needed right now.
 
Aug 18, 2018
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Novi, MI
This is pretty outraging as an advocate for storm chasers. This time where the true importance or storm chasers has been questioned makes these behaviors look much worse. Either way, very disappointed in these chasers.
 
Jun 12, 2019
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Michigan
I’m getting word that a chaser in southern MS crossed a median and is driving on the wrong side of a highway to chase one of the violent tornadoes ongoing. I thought storm chasers were supposed to be “saving lives” and were deemed “essential.” This is pure stupidity. Putting additional lives at risk to chase a storm?

This is supposedly a screenshot from his Twitch live-stream.

View attachment 20290
Nick, are you referencing this twitter post?
 
Jun 12, 2019
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Michigan
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There were cars coming in the opposite direction -- despite what someone else said. What if there was no way to cut back across the median to the correct side? I just don't understand the urgency to track a very fast moving, low visibility tornado? Then again, when you still have news outlets encouraging chasers to "do anything" to get on the air, and other idiots bragging about getting their vehicle destroyed, you don't have to look hard to find the encouragement to do ass clown stunts. Chase-related deaths are like an earthquake fault. The pressure was released several years ago, but now you can just feel the tension building until the next tragedy. It almost let go last year.
 
Jun 16, 2015
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Oklahoma City, OK
quincyvagell.com
I didn’t start a reports thread for this event, because I couldn’t see anything. These tornadoes in Mississippi, even the discrete supercellular ones, were not visible unless you were within a mile and had a clear view.

I was chasing near Soso, close to where the chaser incident happened and I had no visual at all. Only for a brief time could I see the mesocyclone, but trees and very low LCLs were an issue.


Anyway, combine this with storms moving at close to highway speeds and you’re not really chasing. In hindsight, it would have been best to pick a spot and just intercept it, meaning watching it pass by. Knowing how large it was and all the trees, I didn’t dare get too close.

I encountered quite a bit of damage and saw one side of US-84 blocked by trees and debris for about a mile. I almost immediately called the chase off.

There’s no defense for this kind of behavior and to broadcast it live shows even more disregard. Not only are we going to drive dangerously, break traffic laws and put others in danger, but we’re going to show thousands of people in real-time that we have no problem doing it.