Severe Storm Outlook Narrative (AC)
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ACUS01 KWNS 251935
SWODY1
SPC AC 251934

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0234 PM CDT Wed Apr 25 2018

Valid 252000Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE
LOWER/MIDDLE RIO GRANDE VALLEY...

...SUMMARY...
Isolated strong/severe thunderstorms may affect primarily the
lower/middle Rio Grande Valley region of south Texas.

...TX...

No appreciable changes are warranted to 1630z outlook.

Strong surface heating is confined to regions west of the Rio Grande
River and this has contributed to an axis of MLCAPE upwards of 2000
J/kg in the lee of the Sierra Madre Orientals. Strong convection is
evolving over the higher terrain and will soon spread toward lower
elevations. However, it appears the strongest activity should
struggle to spread east of the international border. For these
reasons will maintain 5% severe probs for the U.S. side of the
lower/middle Rio Grande Valley.

..Darrow.. 04/25/2018

.PREV DISCUSSION... /ISSUED 1052 AM CDT Wed Apr 25 2018/

...TX...
A strong cold front is surging southward across the Big Bend region
of TX, and is spreading eastward through the Hill Country.
Scattered elevated thunderstorms are occurring immediately behind
the front, with the potential for hail in the stronger cells
throughout the day.  The air mass ahead of the front continues to
moisten and destabilize, with afternoon MLCAPE values expected to be
around 2000 J/kg.  It appears likely that a few severe thunderstorms
will affect parts of northern Mexico, with some severe threat
extending northward into the Rio Grande Valley of TX.  At this time,
12z guidance and trends in observational data continue to support
that the overall risk in central/south TX is marginal, but an
isolated storm or two could produce large hail and/or damaging winds
this afternoon and evening.

$$



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