SPC MD 1594


MD 1594 Image

Mesoscale Discussion 1594
NWS Storm Prediction Center Norman OK
0639 PM CDT Wed Oct 24 2018

Areas affected...Upper Texas and southwest Louisiana coastal areas

Concerning...Severe potential...Watch unlikely 

Valid 242339Z - 250145Z

Probability of Watch Issuance...5 percent

SUMMARY...Isolated thunderstorm activity impacting upper Texas
(possibly adjacent southwestern Louisiana) coastal areas this
evening may be accompanied by some risk for localized damaging wind
gust and perhaps a tornado.  This risk currently appears low enough
that a watch is not currently anticipated, but trends will continue
to be monitored.

DISCUSSION...Isolated vigorous thunderstorm development, now ongoing
near Galveston, appears focused where low-level convergence has
become maximized to the northeast of a weak area of low pressure,
along a quasi-stationary frontal zone near the upper Texas coast. 
Inflow of seasonably moist air (including boundary layer dew points
around 70F) supportive of CAPE up to 1000 J/kg appears to be
contributing to this activity, though the extent to which ongoing
storms are rooted above at least a shallow near surface stable layer
to the north of the front remains unclear.  Regardless, deep layer
shear near/to the immediate cool side of the front, along coastal
areas across and northeast of Galveston, is strong beneath 35-40 kt
southwesterly 500 mb flow.  

This environment may remain conducive to organized thunderstorm
development, including supercells, through the evening hours, slowly
spreading northeastward ahead of mid-level remnants of Willa, and a
significant short wave trough migrating east northeast  of the
southern High Plains.  Despite somewhat modest low-level hodographs,
this may include some risk for a tornado, mainly where 70F+ surface
dew points advect inland.  Otherwise, localized damaging wind gusts
may be the primary potential severe hazard, as it appears relatively
warm/warming mid-level temperatures may tend to mitigate the risk
for severe hail.

..Kerr/Grams.. 10/24/2018

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


LAT...LON   29689518 29879429 29959356 29569302 29199356 29239435
            28959509 29049555 29689518 

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