SPC MD 5

MD 0005 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR UPPER TEXAS COASTAL PLAIN

MESOSCALE DISCUSSION 0005
NWS STORM PREDICTION CENTER NORMAN OK
0254 PM CST FRI JAN 08 2016

AREAS AFFECTED...UPPER TEXAS COASTAL PLAIN

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 082054Z - 082300Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...AN ISOLATED SUPERCELL STORM OR TWO IS POSSIBLE NEAR OR
SOUTHEAST OF THE GREATER HOUSTON METROPOLITAN AREA LATE THIS
AFTERNOON INTO EARLY EVENING.  MORE SUBSTANTIVE THUNDERSTORM
DEVELOPMENT...WHICH COULD REQUIRE A WATCH...SEEMS MORE LIKELY AFTER
09/00-01Z THAN BEFORE...BUT TRENDS ARE BEING MONITORED.

DISCUSSION...ALTHOUGH THE OFFSHORE GULF OF MEXICO BOUNDARY LAYER IS
NOT PARTICULARLY MOIST...SOUTHERLY LOW-LEVEL FLOW ACROSS THE TEXAS
COAST IS CONTRIBUTING TO MODEST MOISTENING.  INLAND OF COASTAL AREAS
MOISTURE RETURN AND ASSOCIATED DESTABILIZATION APPEAR GENERALLY
ELEVATED ABOVE AT LEAST A SHALLOW RESIDUAL SURFACE BASED STABLE
LAYER.  BUT...ALONG COASTAL AREAS BETWEEN VICTORIA AND
GALVESTON...WHERE SURFACE DEW POINTS ARE IN THE MID 60S...THIS IS
PROBABLY BOUNDARY LAYER BASED.

THIS DESTABILIZATION...COUPLED WITH FORCING FOR ASCENT ASSOCIATED
WITH LOW-LEVEL WARM ADVECTION...HAS CONTRIBUTED TO THE RECENT 
INCREASE IN CONVECTIVE DEVELOPMENT AND THE INITIATION OF
THUNDERSTORM ACTIVITY NEAR UPPER TEXAS COASTAL AREAS.  ASCENT...AND
SUPPRESSION OF AT LEAST WEAK INHIBITION ASSOCIATED WITH ELEVATED
MIXED LAYER AIR EVIDENT IN THE 18Z SOUNDING FROM LAKE CHARLES...MAY
CURRENTLY BE AUGMENTED BY A SUBTLE PASSING MID-LEVEL WAVE.  SO THE
LONGEVITY OF ONGOING ACTIVITY REMAINS A BIT UNCLEAR...WITH
CONSIDERABLE MODEL GUIDANCE...INCLUDING THE RAPID
REFRESH...SUGGESTING THE MORE APPRECIABLE STORM DEVELOPMENT AFTER
09/00Z...WITH THE CONTINUED APPROACH OF THE PRIMARY UPSTREAM
MID-LEVEL WAVE.

IN THE NEAR TERM...INTENSIFICATION OF ONE OR TWO STORMS ACROSS AND
SOUTHEAST OF THE HOUSTON METROPOLITAN AREA DOES NOT APPEAR
COMPLETELY OUT OF THE QUESTION.  ALTHOUGH THE RAPID REFRESH SUGGESTS
SOME WEAKENING OF 20-30 KT SOUTHERLY 850 MB FLOW IS POSSIBLE THROUGH
EARLY EVENING...DEEP LAYER SHEAR SHOULD STILL REMAIN SUFFICIENT FOR
SUPERCELLS.  ANY SUSTAINED DEEP CONVECTIVE DEVELOPMENT MAY BE
ACCOMPANIED BY THE RISK FOR SEVERE HAIL...AND PERHAPS THE RISK FOR
AN ISOLATED TORNADO.

..KERR/CORFIDI.. 01/08/2016

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...LCH...HGX...CRP...EWX...

LAT...LON   29569717 29929709 30449631 30829550 30879478 30319374
            29059416 28679544 28899686 29569717 

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