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Severe Weather Threat - December 12-14, 2022

Mesoscale Discussion 2030
NWS Storm Prediction Center Norman OK
0947 AM CST Wed Dec 14 2022

Areas affected...South-Central/Southeast LA...Central/Southern
MS...Far Southwest AL

Concerning...Tornado Watch 587...

Valid 141547Z - 141745Z

The severe weather threat for Tornado Watch 587 continues.

SUMMARY...Threat for thunderstorms capable of tornadoes will
continue across southern LA, central/southern MS, and far southwest
AL.

DISCUSSION...Recent surface analysis places a low near HEZ in far
southwest MS, A cold front extends from this low southwestward
through south-central LA and a warm front extends east-southeastward
from this low across southern MS and southwest AL (delineated well
by the 64 deg F isodrosotherm). Recent observations show that the
cold front remains progressive across southern LA into the northwest
Gulf of Mexico while the portion of the front closer to the surface
low is becoming less progressive. The warm front has begun lifting
northward as well.

Environmental conditions currently remain favorable for
thunderstorms capable of tornadoes, particularly if any storms can
interact with the warm front and/or undergo updraft intensification
as a result of favorable cell interactions. Over the next few hours,
the warm sector is expected to become increasingly favorable for
discrete supercell development as the shortwave trough over TX
continues quickly eastward and diurnal heating increases. The
low-level flow is forecast to increase across the warm sector as
well. Expectation is for the threat to trend away from the more
linear/cell-in-line mode currently ongoing to a more discrete threat
within the warm sector over the next several hours. A portion of
this region may be upgraded to Moderate with 1630Z Outlook update.

..Mosier/Hart.. 12/14/2022

...Please see www.spc.noaa.gov for graphic product...
Click to expand...
 
the discussion surrounding a growing confidence in a transition to discrete/semi-discrete cells is certainly concerning.

edit: for me personally, i just grew accustomed to the linear mode over the past two days that it didnt cross my mind that today could be different.
 
Last edited:
DISCUSSION...Recent surface analysis places a low near HEZ in far
southwest MS, A cold front extends from this low southwestward
through south-central LA and a warm front extends east-southeastward
from this low across southern MS and southwest AL (delineated well
by the 64 deg F isodrosotherm). Recent observations show that the
cold front remains progressive across southern LA into the northwest
Gulf of Mexico while the portion of the front closer to the surface
low is becoming less progressive. The warm front has begun lifting
northward as well.

Environmental conditions currently remain favorable for
thunderstorms capable of tornadoes, particularly if any storms can
interact with the warm front and/or undergo updraft intensification
as a result of favorable cell interactions. Over the next few hours,
the warm sector is expected to become increasingly favorable for
discrete supercell development as the shortwave trough over TX
continues quickly eastward and diurnal heating increases. The
low-level flow is forecast to increase across the warm sector as
well. Expectation is for the threat to trend away from the more
linear/cell-in-line mode currently ongoing to a more discrete threat
within the warm sector over the next several hours. A portion of
this region may be upgraded to Moderate with 1630Z Outlook update.
Click to expand...
Upgrade to a moderate risk is being considered.
 
CheeselandSkies said:
They toyed with MDT updgrades and PDS watches yesterday and didn't pull the trigger...which in hindsight was an OK call, but would look different had an EF4 gone through Shreveport or Alexandria overnight, which wasn't out of the realm of possibility with the conditions in place.
Click to expand...
They still didn’t know 100% was going to happen because, you know, it’s the weather LOL. They can’t go back AFTER an event and change the risk just bc of said EF4. People get too caught up on the risk categories and if something ends up verifying, and not caught up enough on preparation, executing a plan, etc.

Weather METS always say the same thing: Have several ways to get alerts, have a plan in case they are issued for your area, take action when you receive those alerts.

If someone is impacted by SVR wx, the risk they were in isn’t going to matter after.
 
rolltide_130 said:
MDT out

Click to expand...

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1025 AM CST WED DEC 14 2022

VALID 141630Z - 151200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING OVER PORTIONS OF SOUTHEAST LOUISIANA...SOUTHERN
MISSISSIPPI...AND WESTERN/SOUTHERN ALABAMA...

..SUMMARY

TORNADOES (SOME STRONG) AND DAMAGING THUNDERSTORM GUSTS ARE EXPECTED
TODAY AND TONIGHT ACROSS SOUTHERN PARTS OF LOUISIANA, MISSISSIPPI
AND ALABAMA, AND PORTIONS OF THE FLORIDA PANHANDLE.

...ACTIVE SEVERE WEATHER EVENT IS ANTICIPATED THIS AFTERNOON AND
EVENING FOR PORTIONS OF THE CENTRAL GULF COAST STATES...

..LA/MS/AL

MORNING WATER VAPOR IMAGERY SHOWS AN INTENSE AND PROGRESSIVE
SHORTWAVE TROUGH ROTATING ACROSS OK/TX. THIS FEATURE IS EXPECTED TO
BECOME NEGATIVELY TILTED THIS EVENING OVER AR, WITH STRONG
LARGE-SCALE FORCING OVERSPREADING MUCH OF THE MID/LOWER MS VALLEY.
STRONG SOUTHERLY LOW-LEVEL WINDS HAVE ESTABLISHED A VERY MOIST AND
POTENTIALLY UNSTABLE AIR MASS OVER PARTS OF LA/MS/AL, WITH DEWPOINTS
IN THE 70S AND VISIBLE SATELLITE SHOWING CONSIDERABLE BREAKS IN THE
LOW CLOUDS. THIS SHOULD RESULT IN AMPLE CAPE BY MID-AFTERNOON.

A CONSENSUS OF 12Z CAM GUIDANCE INDICATES THAT DISCRETE SUPERCELL
DEVELOPMENT WILL COMMENCE THIS AFTERNOON OVER SOUTHEAST LA INTO
SOUTHERN MS. THIS ACTIVITY WILL LIKELY PERSIST THROUGH THE EVENING
AND TRACK INTO WESTERN AND SOUTHERN AL. FORECAST SOUNDINGS SHOW
VERY STRONG LOW-LEVEL VERTICAL SHEAR AND FAVORABLE DEEP-LAYER SHEAR
FOR TORNADOES, ALONG WITH SUFFICIENT CAPE FOR ROBUST THUNDERSTORMS.
LOW-LEVEL WINDS ARE EXPECTED TO STRENGTHEN FURTHER DURING THE
AFTERNOON WITH THE APPROACH OF THE UPPER TROUGH. TORNADOES,
INCLUDING THE POSSIBILITY OF STRONG AND LONG-TRACK TORNADOES, ARE
THE PRIMARY CONCERN TODAY. GIVEN THE CONSISTENT SIGNAL IN 12Z
GUIDANCE FOR NUMEROUS SUPERCELLS, THE FAVORABLE CAPE/SHEAR
ENVIRONMENT, AND THE IMPRESSIVE NATURE OF THE SHORTWAVE TROUGH, HAVE
OPTED TO UPGRADE TO MDT RISK FOR PORTIONS OF THE AREA.
 
KevinH said:
They still didn’t know 100% was going to happen because, you know, it’s the weather LOL. They can’t go back AFTER an event and change the risk just bc of said EF4. People get too caught up on the risk categories and if something ends up verifying, and not caught up enough on preparation, executing a plan, etc.

Weather METS always say the same thing: Have several ways to get alerts, have a plan in case they are issued for your area, take action when you receive those alerts.

If someone is impacted by SVR wx, the risk they were in isn’t going to matter after.
Click to expand...

I know. My meaning was simply to point out the very fine line many of these forecasts walk.
 
TornadoFan said:
Already a tornado warning for one of the storms that came off the Gulf.
Click to expand...

pretty notable couplet on that one. though, the one to its SW is also starting to ramp up

161bf84f16f58c5405cc9867bb4de155.jpg
 
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