Mesoscale Discussion 190

Issued

Mar 17, 2021, 1:32 AM CDT (06:32 UTC)

Expired

Mar 17, 2021, 3:30 AM CDT

In force

118 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch possible

Chance of a watch

40%

The Shreveport radar (KSHV), 122 km from the middle of the area, began a volume at 06:34 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

• Severe Thunderstorm Watch 25Mar 17, 4:35 AM CDT

236 
ACUS11 KWNS 170633
SWOMCD
SPC MCD 170632 
MSZ000-ARZ000-LAZ000-TXZ000-OKZ000-170830-

Mesoscale Discussion 0190
NWS Storm Prediction Center Norman OK
0132 AM CDT Wed Mar 17 2021

Areas affected...Portions of northeast TX...northern
LA...southern/central AR...and southeastern OK

Concerning...Severe potential...Watch possible 

Valid 170632Z - 170830Z

Probability of Watch Issuance...40 percent

SUMMARY...If surface-based storms can develop, then a threat for
large hail, damaging wind gusts, and a couple tornadoes would exist.
Watch issuance is possible.

DISCUSSION...An elevated storm in southern AR recently produced
near-severe caliber hail before weakening. Additional convection has
recently developed along the OK/AR border and northeast TX in a
southerly low-level warm advection regime. It remains unclear
whether surface-based storms will develop over the next couple of
hours across the ArkLaTex vicinity, as stronger forcing associated
with an ejecting upper low remains to the west (over the southern
Plains). Regardless, surface dewpoints have generally increased into
the mid to upper 60s across this region, and RAP forecast soundings
suggest that any storms that do develop could become surface based.
Deep-layer shear remains very favorable for supercells (45-50+ kt),
and recent VWPs from KSHV show nearly 40 kt of 0-1 km shear and 250+
m2/s2 0-1 km SRH. Steep mid-level lapse rates noted on the 00Z SHV
sounding combined with the favorable storm mode would support large
hail. Given the enhanced low-level flow/shear, a couple tornadoes
and isolated damaging winds may also occur. At this point, watch
issuance remains uncertain, mainly because it is not clear how many
storms will develop over the next couple of hours in the open warm
sector.

..Gleason/Thompson.. 03/17/2021

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

ATTN...WFO...JAN...LZK...SHV...TSA...

LAT...LON   31839468 32439502 34059522 34769503 35179467 35379432
            35269327 34779195 34169128 33599119 32519185 31889295
            31719400 31839468

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The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.