Tornado Outbreak - S.E. U.S. - 3-17-2021

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Bunkertor
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Tornado Outbreak - S.E. U.S. - 3-17-2021

#1 Postby Bunkertor » Wed Mar 17, 2021 2:16 pm

Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area

HIGH 43,852 3,006,468 Birmingham, AL...Jackson, MS...Tuscaloosa, AL...Hoover, AL...Meridian, MS...

MODERATE 71,084 5,000,778 Memphis, TN...Montgomery, AL...Decatur, AL...Pine Bluff, AR...Monroe, LA...

ENHANCED 102,738 10,707,136 New Orleans, LA...Baton Rouge, LA...Shreveport, LA...Mobile, AL...Columbus, GA...

SLIGHT 91,657 10,820,726 Nashville, TN...Atlanta, GA...Chattanooga, TN...Clarksville, TN...Beaumont, TX...

MARGINAL 90,366 14,037,869 Houston, TX...Tulsa, OK...St. Louis, MO...Pasadena, TX...Evansville, IN...

SPC AC 171606

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1106 AM CDT Wed Mar 17 2021

Valid 171630Z - 181200Z

...THERE IS A HIGH RISK OF SEVERE THUNDERSTORMS WEST-CENTRAL
ALABAMA...NORTHERN AND CENTRAL MISSISSIPPI...NORTHEAST
LOUISIANA...FAR SOUTHEAST ARKANSAS...

...SUMMARY...
A significant tornado outbreak is expected with numerous strong and
a few long-track, potentially violent tornadoes. An initial round is
expected to begin across eastern Mississippi and Alabama this
afternoon. A separate swath should emanate from southeast Arkansas
to Louisiana this afternoon and spread east across Mississippi and
Alabama this evening into tonight.

...Deep South...
Minor change made to the categorical HIGH risk area to expand a bit.
Main change is to the underlying probabilities with the addition of
a 45 tor and 45 wind. A dangerous, long-duration tornado outbreak
expected to commence this afternoon and persist well into tonight
with multiple rounds of heightened tornado potential.

Ongoing convection is within an arc with a pre-frontal squall from
far east TX to northeast AR and then in a more west/east-orientation
from northeast AR to the AL/TN border area. The northern activity
will tend to reinforce the surface warm front approaching the TN
border with MS/AL this afternoon. The southwest band will likely
persist east and should breakup into a broken band of supercells at
some point this afternoon as low-level shear further strengthens
across the Ark-La-Miss region. Farther east, warm-advection showers
in southeast MS to west-central AL will likely deepen by early
afternoon into a separate swath of several discrete supercells in an
environment of strengthening low to deep-layer shear. Between these
two areas, the destabilizing warm sector with warming boundary-layer
temperatures and mid 60s to low 70s dew points, will support an
expansive plume of 1500-2500 J/kg MLCAPE.

By late afternoon and into early tonight, a low-level jet segment
will strengthen to at least 50-60 kt across MS/AL as the midlevel
trough approaches from the west, contributing to very strong
low-level shear (0-1 km SRH in excess of 300 m2/s2). Buoyancy will
be slow to decrease after sunset and with eastward extent based on
the prevalence of rather rich boundary-layer dew points, Very
favorable wind profiles (with 700-mb winds reaching 70-80 kt) will
maintain the threat for long-track, intense tornadoes with both
warm-sector supercells, as well as supercells within the broken band
near and ahead of the surface wind shift progressing east across MS
by early tonight. The strong tornado and significant damaging wind
threat while becoming more spatially confined with time, will likely
persist across parts of AL overnight and should spread into western
GA before 12Z.

..Grams/Bentley.. 03/17/2021
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Re: Tornado Outbreak - S.E. U.S. - 3-17-2021

#2 Postby Bunkertor » Wed Mar 17, 2021 3:53 pm

LCL in Birmingham 76 m, Jackson, MS no cap.
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Re: Tornado Outbreak - S.E. U.S. - 3-17-2021

#3 Postby Bunkertor » Wed Mar 17, 2021 3:58 pm

New Orleans sounding 18z :double:
Image
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Re: Tornado Outbreak - S.E. U.S. - 3-17-2021

#4 Postby Bunkertor » Wed Mar 17, 2021 4:22 pm

892
WFUS54 KMOB 172117
TORMOB
ALC023-025-172200-
/O.NEW.KMOB.TO.W.0010.210317T2117Z-210317T2200Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE MOBILE AL
417 PM CDT WED MAR 17 2021

THE NATIONAL WEATHER SERVICE IN MOBILE HAS ISSUED A

* TORNADO WARNING FOR...
SOUTHEASTERN CHOCTAW COUNTY IN SOUTHWESTERN ALABAMA...
NORTHWESTERN CLARKE COUNTY IN SOUTHWESTERN ALABAMA...

* UNTIL 500 PM CDT.

* AT 416 PM CDT, A CONFIRMED LARGE AND EXTREMELY DANGEROUS TORNADO
WAS LOCATED 7 MILES EAST OF GILBERTOWN, OR 16 MILES SOUTH OF
BUTLER, MOVING NORTHEAST AT 35 MPH.


THIS IS A PARTICULARLY DANGEROUS SITUATION. TAKE COVER NOW!

HAZARD...DAMAGING TORNADO.

SOURCE...RADAR CONFIRMED TORNADO.

IMPACT...YOU ARE IN A LIFE-THREATENING SITUATION. FLYING DEBRIS
MAY BE DEADLY TO THOSE CAUGHT WITHOUT SHELTER. MOBILE
HOMES WILL BE DESTROYED. CONSIDERABLE DAMAGE TO HOMES,
BUSINESSES, AND VEHICLES IS LIKELY AND COMPLETE
DESTRUCTION IS POSSIBLE.

* THIS TORNADIC THUNDERSTORM WILL REMAIN OVER MAINLY RURAL AREAS OF
SOUTHEASTERN CHOCTAW AND NORTHWESTERN CLARKE COUNTIES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...
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