Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
SPC AC 211627
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1027 AM CST Sat Jan 21 2017
Valid 211630Z - 221200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
SOUTHERN AR...WESTERN MS...AND NORTHERN LA...
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM THE
ARKLATEX REGION EASTWARD ACROSS THE GULF COAST STATES...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE LOWER MS
VALLEY INTO THE CAROLINAS...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE LOWER
MS VALLEY INTO THE CAROLINAS...
Multiple rounds of severe thunderstorms are expected today through
early Sunday from Louisiana/Arkansas eastward to north Florida,
Georgia and South Carolina. The severe weather threat will cover
the full spectrum from isolated strong tornadoes to very large hail
and damaging winds.
...AL/FL/GA/SC This Afternoon...
A fast moving and intense squall line is moving rapidly eastward
across parts of the FL Panhandle, extreme southeast AL, and
southwest GA. This line will progress across GA and into SC later
today. Transient rotating updrafts have been occurring along the
line this morning, producing locally damaging wind gusts and
tornadoes. This threat will persist as activity moves eastward due
to strong southerly low level winds just ahead of the storms
maintaining enhanced low level shear and helicity values. Some
breaks in the clouds and modest afternoon heating may further
destabilize the area and maintain the Enhanced risk of severe
...AR/LA/MS This Afternoon and Evening...
Water vapor loop shows a lead shortwave trough moving eastward
across the Gulf Coast states. Subsidence behind this system will
help to suppress deep convection over the ArkLaTex region for a few
more hours. However, another shortwave trough over NM and West TX
will lead to increasing lift and cooling aloft by mid/late
afternoon. Present indications are that scattered thunderstorms
will develop over southeast OK and northeast TX around peak heating
and track eastward across parts of AR/LA and into MS this evening.
Forecast soundings show steep lapse rates, cold mid level
temperatures, and favorable deep layer shear values to promote a
widespread risk of severe hail. CAM solutions also indicate
discrete supercells will be favored, further increasing the risk of
very large hail and a few tornadoes. Therefore have upgraded
portions of this area to MDT risk for the hail threat.
...LA/MS/AL/GA This Evening and Tonight...
Considerable uncertainty exists regarding the evolution of the
remnant outflow boundary from this morning's convection and the
re-development of thunderstorms tonight over this area. Forecast
soundings indicate that the combination of sufficient instability,
ample low level moisture, and significant low level vertical shear
will promote a tornado risk in any storms that form. A few models
suggest another active round of severe storms affecting areas
similar to this mornings storms. Therefore will maintain the
Enhanced Risk area with minimal changes.
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