Severe Storm Outlook Narrative (AC)
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ACUS01 KWNS 260042
SWODY1
SPC AC 260041

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0741 PM CDT Wed Apr 25 2018

Valid 260100Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTH TEXAS...

...SUMMARY...
Isolated strong to severe thunderstorms may continue to affect parts
of south Texas this evening.

...South Texas...
The latest water vapor imagery shows an upper-level low over the
central states with an upper-level trough extending southwestward
into the southern Plains. The southern extension of the trough is
located across the lower Rio Grande Valley and a plume of mid-level
moisture is present ahead of the trough along the Texas Coastal
Plain. Scattered thunderstorms are ongoing within this plume along a
corridor of instability. The RAP is analyzing this corridor of
instability across the western part of south Texas where MLCAPE
values are estimated in the 250 to 500 J/kg range. In addition, the
00Z soundings at Corpus Christi and Brownsville both have 45 to 50
kt of 0-6 km shear with some directional shear in the lowest 3 km
AGL. This combined with steep mid-level lapse rates around 7.5 C/km
may be enough to continue a marginal severe threat for a couple more
hours. However, as storms approach the lower Texas Coast this
evening where instability is considerably weaker, convection should
gradually weaken.

..Broyles.. 04/26/2018

$$



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