Severe Storm Outlook Narrative (AC)
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ACUS11 KWNS 242155
SPC MCD 242155

Mesoscale Discussion 0288
NWS Storm Prediction Center Norman OK
0455 PM CDT Tue Apr 24 2018

Areas affected...Portions of west TX

Concerning...Severe potential...Watch unlikely

Valid 242155Z - 250030Z

Probability of Watch Issuance...20 percent

SUMMARY...An isolated damaging wind and hail threat should develop
eastward this evening. Watch issuance is unlikely mainly due to the
marginal thermodynamic environment.

DISCUSSION...Isolated thunderstorms have formed this afternoon along
and just ahead of a surface trough located over west TX. Surface
temperatures have warmed into the upper 80s and lower 90s across
this region, but low-level moisture return has been very limited
thus far. Large temperature-dewpoint spreads generally around 40-45
degrees imply a very well-mixed boundary layer, and convective
downdraft winds will likely be enhanced as they reach the surface,
possibly producing isolated severe-caliber gusts. Although winds in
the 0-3 km layer remain weak per 2136Z VWP from KLBB, they do veer
and strengthen slightly into mid-levels. This is supporting
effective bulk shear values around 30-35 kt, which should be
marginally supportive of organized updrafts and perhaps some hail
threat with the strongest cores. Tendency with time should be for
convection to congeal into some form a loosely organized
line/cluster as it moves eastward this evening, with strong to
locally damaging winds becoming the primary threat. The limited
low-level moisture and resultant marginal thermodynamic environment
should tend to keep the overall severe threat isolated, and watch
issuance appears unlikely at this time.

..Gleason/Thompson.. 04/24/2018

...Please see for graphic product...


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