Wednesday, April 2, 2025

New SPC Outlook


The new Storm Prediction Center outlook shows things about the same. Except the high risk for tornadoes is centered around Memphis now. 


The threat for a tornado within 25 miles of a given point is about 30% in that highest threat area, about 15% for much of Western Tennessee, then drops to about 10% for the Nashville metro area and that corridor, then down to 2-5% for most of Southern Middle Tennessee into far North Alabama. 


There is also a threat for damaging winds and large hail with these storms. But look, there has been significant tornado damage in Arkansas already. So if I'm going to comment on this event, the main focus is going to be on who is likely to see a tornado. 



Most of us in North Alabama and Southern Middle Tennessee only have a minimal risk of that roughly after Midnight tonight. The threat is a little enhanced in the far Northwest corner of Alabama up through places like Waynesboro, Lawrenceburg, up to Nashville. 

Most of us probably have no problems with severe weather tonight, but have a way to get warnings that will wake you up. 

Ideally that's a NOAA Weather Radio properly set with battery backup. But almost everybody now has a cell phone, and they all have the ability to get Wireless Emergency Alerts, even the cheaper flip phones have that now. 

Another option is to tune to a radio station that you know will cut in for bad weather. Especially if you fall asleep listening to classical music, that EAS tone sure is jarring in the middle of the night. Just don't rely on an outdoor siren. And I'm mainly talking to people up across the TN state line. Just have a reliable source of getting the warning, and have a safety plan. 

In your shelter room, that lowest, most central room of your home, it's good to shield your body in case of any falling (or flying) debris. Especially protect your head. If you have an old football or bike helmet, get it ready before the storms get to you and then if you have to shelter tonight, put it on. It's better safe than sorry when dealing with a cluster or line of storms with a history of producing significant damage. 

If you're on the Alabama side, probably no issues tonight, but I wouldn't take that to the bank. Again, it's better safe than sorry sometimes. Just in case a storm made it down this way a little and got out of hand, it's better to be prepared. But the threat in North AL looks very low.  

9:14 PM - And man, that tornado that hit Lake City, Arkansas sure looked like a doosie. 

Two people I know, one in Tennessee, the other in Indiana, said today reminded them of living through April 3-4, 1974. I can see the comparison in a way. It's way too warm, way too far North. And it's windy. And there is tornado potential across several states, lasting from the day into the night hours. And some of those tornadoes were expected to be strong-to-violent (rated E/F-3 or higher), like that was specifically mentioned in the SPC outlook earlier in the day. And what we've seen so far, looks like some of those forecasts verified, at least in Arkansas. 

But we'll see how it stacks up historically. You know, everybody remembers that April 1974 event this time of year in Alabama. But there was another event in 1977, April 4, on Smithfield Drive in Birmingham, where there was only one F-5 tornado. Five other tornadoes in the event were rated F-2, and one was rated F-3. So technically it was nowhere near as bad as the April 3, 1974 event. Yet people who lived through it or worked it felt like it was just about as bad. 

Instead of playing the comparison game just yet, I think I'll just say that any day/night you've got potential for multiple supercell thunderstorms capable of producing strong-to-violent tornadoes can be a nightmare for the people who are affected. 


And the National Weather Service in Paducah, Kentucky actually had to take shelter while a tornado passed just South of them tonight. It may have hit the airport. They lost power at the NWS office and are having to run on a generator for the time being. It was about an hour ago that they had to shelter. 

9:26 PM - Folks in Middle Tennessee need to either monitor the progress of these storms or have a way of waking up for warnings later tonight in case they are required. Actually on second thought, both of those things would be just fine. Can stay up and watch it if you like, but most important thing is to have a way to wake up so you can take shelter if severe storms threaten later. 

9:46 - And now I'm just going to pass along some words directly from NWS Nashville in their latest update to the forecast discussion:

Area Forecast Discussion

National Weather Service Nashville TN

938 PM CDT Wed Apr 2 2025


...New SHORT TERM, LONG TERM...


.KEY MESSAGES...

Updated at 912 PM CDT Wed Apr 2 2025


- There is a level 4 out of 5 risk for severe storms tonight for

  many of our western counties with a level 3 out of 5 for

  Nashville Metro and surrounding areas. Storms are expected to

  begin moving in from the west late this evening, spreading

  across the northwest half of Middle Tennessee through the late

  night hours. Damaging winds, tornadoes, large hail, and

  torrential downpours will all be possible. Locations around and

  west of Linden, Waverly, Clarksville, and Dover are at greatest

  risk for strong, long track tornadoes late this evening. 


- Major flooding may develop for northwest Middle Tennessee with

  torrential rainfall at times from this evening through Sunday

  morning. Stewart, Montgomery, and Houston Counties are at

  greatest risk with 10 inches of rainfall possible. Nashville

  Metro could have more than 6 inches of rain. Flash flooding and

  eventually river flooding will be concerns across the northwest

  half of Middle Tennessee where a Flood Watch is in place.


- There will be a continued risk for severe storms across the area

  Thursday through Saturday. The greatest risk will continue to be

  over the northwest half of Middle Tennessee with much lower 

  storm chances over the southeast half. Damaging winds will be 

  the main concern Thursday through Saturday, although tornadoes 

  cannot be ruled out. 

This certainly is a complex weather setup for Tennessee. 

9:50 - Another note on the Lake City, Arkansas tornado earlier: The radar debris signature showed things being picked up to about 30,000 feet. If this verifies with ground truth in the surveys tomorrow, then this tornado will probably be rated at least E/F-4. Or I guess if it only hit weak structures, maybe a high-end E/F-3? But this looks like it was one of those rare, awful tornadoes. Everything I see coming out about it, videos of the vortex, damage pictures, radar data . . . looks like a really rare tornado. 
9:53 - And within the past 30 minutes, a tornado was spotted in Indiapolis. This is quite a night. 


10:02 PM - And the threat for this Tornado Watch in Tennessee continues. The main threat is transitioning to damaging thunderstorm winds as the storms have formed into a squall line and a lot of the stronger convection is being undercut by a cold pool that has formed over Middle TN. But some risk for isolated tornadoes will persist within this line tonight, at least for the next couple hours. 


10:07 - Currently no issues in North Alabama or the bordering counties of Southern Middle Tennessee though. Probably not going to see anything on the Alabama side, unless it's around the Shoals. 

10:28 - Earlier I mentioned two people saying this setup reminded them (in TN and IN) of the 1974 tornado outbreak around this time of year. In meteorological terms, that is nonsense. The only event we've had since then that was comparable was the 2011 outbreak. But subjectively from people who lived through 1974, today's setup brought back some bad memories. That's all I meant by that. Objectively, no, it is nowhere close. But every event is unique. And I wouldn't be surprised if this is one of those events that people especially in Arkansas remember for many years to come. 

10:31 - Things are calming down somewhat as a cold pool has formed out ahead of it and the storms have formed into this long line now. Damaging winds are the main threat, but isolated tornadoes are still possible within the line. 


It's unlikely we'll see any issues even in far Northwest Alabama up to like Waynesboro, but it's not impossible before the night is over. So sleep with a weather radio on alert, or at least a cell phone with WEA. I'm not close enough to that area to get their alarms. But if you're going to be in the path, you need that way to get warnings that'll wake you up. 


11:08 PM - The severe weather threat is slow to diminish with this vigorous squall line, and they are thinking about issuing more watches upstream for the continued threat of damaging wind gusts or an isolated tornado.

SPC AC 030055


   Day 1 Convective Outlook  

   NWS Storm Prediction Center Norman OK

   0755 PM CDT Wed Apr 02 2025


   Valid 030100Z - 031200Z


   ...THERE IS A HIGH RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN

   ARKANSAS INTO SOUTHERN ILLINOIS...


   ...SUMMARY...

   A tornado outbreak is ongoing across parts of the lower Mississippi

   Valley into the Mid-South and lower Ohio Valley. Numerous tornadoes,

   along with multiple EF3+ tornadoes, remain likely. Additionally,

   tornadoes, significant severe wind gusts, and large hail to very

   large hail remain possible across a broad area from north Texas

   northeastward to the southern Great Lakes.


   ...01z Update...


   An elongated corridor of severe thunderstorms has evolved from

   southern Arkansas, northeast across the Boot Heel of Missouri into

   northern Indiana. Numerous tornadic supercells are noted along this

   zone, especially across the High Risk area from southern Arkansas

   into southern Illinois. Multiple long-lived tornadoes have likely

   produced significant damage in places, and this threat will continue

   into the late evening/overnight hours.


   Intense LLJ is forecast to translate across the western Tennessee

   Valley into the lower Great Lakes, and this will contribute to a

   northeastward shift of organized convection after midnight as the

   primary short-wave trough ejects toward lower Michigan.

   Environmental parameters continue to favor strong tornadoes and

   damaging winds, along with large hail.


   Upstream across Texas, a secondary low-latitude short-wave trough

   will approach far West Texas late in the period. In response to this

   feature, LLJ is forecast to increase across the Edwards Plateau by

   03/06z, and strengthening is expected as the LLJ shifts toward the

   I35 corridor by sunrise. Significant destabilization is expected

   into north-central Texas late as moisture surges north. As a result,

   supercells are expected to develop and spread east-northeast.


   ..Darrow.. 04/03/2025


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