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Pi Day 3/14/19 severe weather regional outbreak

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Twitter has safe tornado videos at #kywx and probably other #/@ tags. Atmosphere has tipped its hand on the synoptic fronts. How about boundaries farther south? They are usually second to go; so, this is very much still an ongoing day for Dixie (as of Noon Central Time).

Noon Central Time: Differential heating and dewpoint boundary is noted from North Alabama into West Tenn. Another boundary is lifting from central Mississippi. They may merge later farther north. Either way looks like locally enhanced helicity in the usual suspect areas of North Alabama into northeast Mississippi and southern Middle Tenn. 

Upper air wind fields are strong including proper turning with height. 700 mb is a little warm; but, I expect enough surface convergence to overcome. Synoptic trough is coming out of Arkansas, and will bump into the above boundary(ies). North Bama clouds are decreasing both sides of lifting boundary, an ominous sign. Oh that boundary looks like an extension of the Georgia cool wedge-front, where clearing is also seen both sides.

Warm mid-levels and neutral heights from yesterday will have less impact if foretasted surface heating materializes.  Plus convergence along boundaries should be enough, esp intersecting ones.

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   URGENT - IMMEDIATE BROADCAST REQUESTED
   Tornado Watch Number 25
   NWS Storm Prediction Center Norman OK
   1210 PM CDT Thu Mar 14 2019

   The NWS Storm Prediction Center has issued a

   * Tornado Watch for portions of 
     Northwestern Alabama
     Northeastern Mississippi
     Parts of western and middle Tennessee

   * Effective this Thursday afternoon and evening from 1210 PM
     until 700 PM CDT.

   * Primary threats include...
     Several tornadoes likely with a couple intense tornadoes
       possible
     Scattered damaging wind gusts to 70 mph likely
     Isolated large hail events to 1 inch in diameter possible

   SUMMARY...Scattered thunderstorms will likely intensify in a broken
   band through the afternoon from northeastern Mississippi into
   northwestern Alabama and middle Tennessee.  The storm environment
   will be favorable for supercells capable of producing a couple of
   strong tornadoes, along with damaging winds and isolated large hail.

   The tornado watch area is approximately along and 55 statute miles
   east and west of a line from 10 miles east northeast of Clarksville
   TN to 35 miles south southeast of Columbus MS. For a complete
   depiction of the watch see the associated watch outline update
   (WOUS64 KWNS WOU5).

   PRECAUTIONARY/PREPAREDNESS ACTIONS...

   REMEMBER...A Tornado Watch means conditions are favorable for
   tornadoes and severe thunderstorms in and close to the watch
   area. Persons in these areas should be on the lookout for
   threatening weather conditions and listen for later statements
   and possible warnings.

   &&

   OTHER WATCH INFORMATION...CONTINUE...WW 24...

   AVIATION...Tornadoes and a few severe thunderstorms with hail
   surface and aloft to 1 inch. Extreme turbulence and surface wind
   gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean
   storm motion vector 24045.

   ...Thompson

 

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This day resembles several infamous days such as 4/3/74 and 11/10/02 in the area threatened. Obviously today was much more conditional and probably won't have has much coverage of significant severe (otherwise it would have been a high risk with PDS watches in effect), but certainly the potential for several sig tors from Alabama to IN/OH.

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Has anyone else noticed that MEG's wording is a bit...confusing? It reads like a TOG situation but as far as I can tell that isn't the case.

Quote
The National Weather Service in Memphis has issued a

* Tornado Warning for...
  Southeastern Hardin County in western Tennessee...

* Until 115 PM CDT.

* At 1228 PM CDT, doppler radar indicated a severe thunderstorm
  producing a tornado was located near J P Coleman State Park, moving
  northeast at 40 mph.

  HAZARD...Tornado and quarter size hail.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without
           shelter. Mobile homes will be damaged or destroyed.
           Damage to roofs, windows, and vehicles will occur.  Tree
           damage is likely.

* Locations impacted include...
  Walnut Grove, Lowryville, Center Star, Pollards Mill and Winn
  Springs.

 

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Wall cloud reported in Monroe County, MS...
 

Quote
...A TORNADO WARNING REMAINS IN EFFECT UNTIL 115 PM CDT FOR SOUTHERN
MONROE COUNTY...

At 1243 PM CDT, doppler radar indicated a severe thunderstorm
producing a tornado was located near Prairie, or 8 miles north of
West Point, moving northeast at 35 mph.

HAZARD...Tornado and quarter size hail.

SOURCE...Radar indicated rotation. a wall cloud has been reported
         with this storm.

IMPACT...Flying debris will be dangerous to those caught without
         shelter. Mobile homes will be damaged or destroyed. Damage
         to roofs, windows, and vehicles will occur.  Tree damage is
         likely.

 

New warning for Central Tishomingo County in northeastern MS as well.

Quote
The National Weather Service in Memphis has issued a

* Tornado Warning for...
  Central Tishomingo County in northeastern Mississippi...

* Until 130 PM CDT.

* At 1252 PM CDT, doppler radar indicated a severe thunderstorm
  producing a tornado was located over Midway, or near Iuka, moving
  northeast at 35 mph.

  HAZARD...Tornado and quarter size hail.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without
           shelter. Mobile homes will be damaged or destroyed.
           Damage to roofs, windows, and vehicles will occur.  Tree
           damage is likely.

 

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Possible TOG west of Hackleburg, AL. Tight couplet with a what may well be a small debris ball. It's been over an unwarned area but is now moving into a preexisting polygon. Weird situation.

Ninja edit: looks like HUN had a beat on that cell and issued a warning well in advance for a border county. Looks like it produced while in BMX territory and was not warned. 

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Latest AFD from MRX:

.SHORT TERM...(Tonight and Friday)...
Storms with supercell structure have been increasing across N AL
and Middle TN over the past hour. The short term models indicate
that the environmental shear and instability will remain
supportive of supercells, and the RAP shows strengthening
mesoscale forcing as storms move into our area.

The period of the greatest severe threat will be between 7 pm and
midnight. Damaging winds with be the main threat with the storms,
and tornadoes will also be possible given the high shear and low
LCL environment. The Plateau and southern TN Valley will be the
areas of greatest concern for tornadoes. The eastern half of the
area will still have a threat of straight line winds but storms
should generally be weakening after moving past Knoxville, which
should occur around 10 pm to midnight.

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Almost everything north of TN/MS and TN/AL borders fired as junkvection. Storms in MS/AL exhibited rotation, but evidently nothing was strong enough to produce (contrary to my analysis above). 

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Just as I say that, the best looking couplet of the day in AL/MS develops in Cullman Co.

Quote
The National Weather Service in Huntsville Alabama has issued a

* Tornado Warning for...
  Central Cullman County in north central Alabama...

* Until 430 PM CDT.

* At 403 PM CDT, a severe thunderstorm capable of producing a tornado
  was located over Good Hope, or near Cullman, moving northeast at 50
  mph.

  HAZARD...Tornado and quarter size hail.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without
           shelter. Mobile homes will be damaged or destroyed.
           Damage to roofs, windows, and vehicles will occur.  Tree
           damage is likely.

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ULLETIN - EAS ACTIVATION REQUESTED  
TORNADO WARNING  
NATIONAL WEATHER SERVICE BIRMINGHAM AL  
650 PM CDT THU MAR 14 2019  
  
THE NATIONAL WEATHER SERVICE IN BIRMINGHAM HAS ISSUED A  
  
* TORNADO WARNING FOR...  
  CENTRAL CHILTON COUNTY IN CENTRAL ALABAMA...  
  SOUTHEASTERN BIBB COUNTY IN CENTRAL ALABAMA...  
  
* UNTIL 730 PM CDT.  
      
* AT 650 PM CDT, A TORNADO PRODUCING STORM WAS LOCATED NEAR TALLADEGA  
  NATIONAL FOREST, OR 8 MILES SOUTHEAST OF BRENT, MOVING EAST AT 30  
  MPH.  
  
  HAZARD...DAMAGING TORNADO.  
  
  SOURCE...RADAR CONFIRMED TORNADO.  
  

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With the nature of the storm mode we had today, and lack of the usual wrenches like coastal convection or upscale growth/cell interference... I have a feeling we were just a few more degrees in the dewpoint/a couple hundred more j/kg in the lowest 3km removed from multiple events the caliber of Beauregard-Smith's Station.

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I killed the Tennessee Valley part of the event. Mets should not start event threads, lol. I jinxed a couple snows few years back; apparently, it's the same with severe. If you don't like tornadoes, you're welcome lol!

Unfortunately tornadoes did verify and cause damage north and south (Midwest and central Alabama). Fortunately I did not chase 3/14. That is 4 Dixie events I've passed on. Here is a look at 3 boundaries which intersected the synoptic trough from the west (by increasing impact).

Tenn Valley had the issues at 700 mb. Mid levels were too warm and heights were neutral. Then low clouds hung in (after initially decreasing). Boundary along Tenn border with MS/AL (#3) got a little washed out and/or relegated.

Farther south into Alabama had the instability Cheese notes was missing in the Tenn Valley. Distinct differential heating boundary (#2) was noted also across central Miss and central Bama, more sun south of it. There you go! 

Synoptic boundaries (trough/WF) in the Midwest ruled the day. While I usually favor outflow boundaries farther south, they still require the right conditions (where were absent Tenn Valley). Midwest had height falls and cooling temps mid levels including 700 mb. 

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