SPC MD 70

MD 0070 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF SOUTHEASTERN TEXAS ANS SOUTHWESTERN LOUISIANA

Mesoscale Discussion 0070
NWS Storm Prediction Center Norman OK
0241 PM CST Wed Jan 18 2017

Areas affected...Parts of southeastern Texas ans southwestern
Louisiana

Concerning...Severe potential...Watch unlikely 

Valid 182041Z - 182315Z

Probability of Watch Issuance...5 percent

SUMMARY...Thunderstorms may continue to strengthen across upper
Texas coastal areas, into adjacent southwestern Louisiana, through
22-23Z.  Severe weather potential does not appear enough to require
a watch, but eventually activity could become capable of producing
occasional strong surface gusts approaching or briefly exceeding
severe limits.

DISCUSSION...Low-level convergence appears enhanced, within a zone
along a 20-30 kt southerly 850 mb jet extending inland across upper
Texas coastal areas near/east of the Greater Houston Metropolitan
area, providing support for a sustained band of convection.  This
band is most vigorous inland of coastal areas, where surface heating
has contributed to weak boundary layer destabilization (CAPE up to
around 500 J/kg), with some recent intensification underway as this
instability begins to peak.

Relatively warm mid/upper level temperatures, in the presence of
weak to negligible mid/upper forcing for ascent, may still be
suppressing activity somewhat.  However, at least some further
intensification of thunderstorm activity appears probable through
22-23Z.  

Veering of winds with height in lower-levels has already supported
occasional weak rotation in some cells.   And the latest Rapid
Refresh suggests some further strengthening in 850 mb flow (to 30-35
kt) is possible near upper Texas coastal areas by early evening. 
Beneath 30-40+ kt southwesterly 700-500 mb flow, the environment may
become marginally conducive to an organizing line of storms with
some risk for potentially damaging surface gusts.  This may be aided
by heavy precipitation loading in the presence of seasonably high
precipitable water content.

..Kerr/Guyer.. 01/18/2017

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

ATTN...WFO...LCH...HGX...

LAT...LON   30399426 31049387 31029320 30599278 29759337 29389411
            29299471 29839443 30399426 

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