Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 211508
SWOMCD
SPC MCD 211507
LAZ000-MSZ000-TXZ000-211700-

Mesoscale Discussion 0080
NWS Storm Prediction Center Norman OK
0907 AM CST Wed Feb 21 2018

Areas affected...Central/Southern LA...Far Southeast TX

Concerning...Severe potential...Watch possible

Valid 211507Z - 211700Z

Probability of Watch Issuance...40 percent

SUMMARY...Damaging wind gusts and perhaps a tornado or two are
possible across portions of central and southern LA during the next
several hours. An upgrade to 5% tornado probabilities is anticipated
across portions of the area in the forthcoming 1630Z Convective
Outlook.

DISCUSSION...Regional radar imagery shows a cluster of supercells
along the southern TX/LA border in or entering Vernon and Beauregard
parishes. KPOE reveals the rotation within these storms well with
the storm in Vernon perish showing the strongest rotation and
updraft strength. Downstream airmass is moist, uncapped, and
moderately unstable, suggesting these storms should remain strong
for at least the next hour. Any storm weakening or dissipation would
likely be a result of negative storm interactions not thermodynamic
or kinematic factors. Additional development is possible within or
just ahead of this cluster as low-level confluence continues ahead
of the approaching cold front.

VAD wind profile from KLCH recently sampled 0-1 km SRH over 250 m2
per s2 and both KLCH and KPOE sampled 0-1 km shear around 25 kt.
This type of kinematic environment is favorable for low-level
rotation and the potential for a few tornadoes. Given the
anticipated persistence of this environment, portions of this area
will be upgraded to 5% tornado probabilities with the upcoming 1630Z
Convective Outlook and a watch is being considered.

..Mosier/Thompson.. 02/21/2018

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...JAN...LIX...LCH...SHV...

LAT...LON   30669401 31479357 31959275 32139210 32069157 31869138
            31509142 30949168 30619186 30379200 30079218 29839241
            29629301 29729368 30049400 30669401




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