Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS01 KWNS 191303
SWODY1
SPC AC 191301

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0701 AM CST FRI DEC 19 2014

VALID 191300Z - 201200Z

...NO SVR TSTM AREAS FORECAST...

...SUMMARY...
WIDELY SCATTERED THUNDERSTORMS ARE POSSIBLE TODAY OVER PARTS OF
CENTRAL AND SOUTH TEXAS...ACROSS SOUTHERN LOUISIANA TO
MOBILE/PENSACOLA AREAS.

...SYNOPSIS...
UPPER-AIR PATTERN IS FCST TO REMAIN FAIRLY LOW-AMPLITUDE
SYNOPTICALLY...AND PROGRESSIVE IN NATURE...AS NUMEROUS MAINLY
LOW-AMPLITUDE PERTURBATIONS TRAVERSE CONUS.  SHORTWAVE TROUGH NOW
LOCATED OVER W TX IS EXPECTED TO DEAMPLIFY GRADUALLY AS IT MOVES
ENEWD TO ARKLATEX REGION BY 00Z...AND SRN APPALACHIANS BY END OF
PERIOD.

AT SFC...LOOSELY ASSOCIATED FRONTAL-WAVE LOW WAS ANALYZED AT 11Z
OVER MIDDLE TX COASTAL PLAIN JUST INLAND FROM CRP...WITH
WAVY/QUASISTATIONARY FRONT ENEWD OVER MIDDLE-UPPER TX COASTAL WATERS
AND OFFSHORE LA.  COLD FRONT EXTENDED FROM LOW SWD ACROSS LOWER TX
COASTAL COUNTIES AND OVER COASTAL PLAIN OF EXTREME NERN MEX.  WITH
PRIMARY SHORTWAVE TROUGH PASSING N OF THIS REGION WHILE
WEAKENING...SFC LOW IS FCST TO REMAIN WEAK AND MOVE SLOWLY EWD THEN
ENEWD OVER NWRN GULF ALONG FRONTAL ZONE.  LOW SHOULD REMAIN MOSTLY
OVER WATER...THOUGH IT MAY REACH MS RIVER MOUTH AROUND 20/12Z.
FRONT ALSO SHOULD REMAIN OFFSHORE EXCEPT NEAR RIVER MOUTH.

...CENTRAL/S TX TO CENTRAL GULF COAST...
WIDELY SCATTERED TSTMS IN CLUSTERS SHOULD PERSIST THROUGH REMAINING
DAYLIGHT HOURS...BEFORE WEAKENING OF LIFT AT ALL SCALES LESSENS
COVERAGE OF SUFFICIENTLY DEEP CONVECTION.  MEANWHILE...LOW-LEVEL WAA
AND ISENTROPIC LIFT TO LFC WILL SUPPORT CONVECTIVE POTENTIAL FROM NW
OF SFC LOW TO N OF QUASISTATIONARY FRONT...AMIDST POCKETS OF
ELEVATED MUCAPE GENERALLY BELOW 500 J/KG.  REINFORCEMENT OF
LOW-LEVEL STATIC STABILITY FROM PROFUSE PRECIP SHIELD NOW OVER SE TX
AND LA SHOULD HELP TO KEEP FRONTAL ZONE AND SFC-BASED
EFFECTIVE-INFLOW PARCELS FROM REACHING INLAND THROUGH PERIOD.
THIS...IN COMBINATION WITH WEAK LAPSE RATES ALOFT AND RESULTANT
MEAGER BUOYANCY...SHOULD LIMIT POTENTIAL FOR STG GUSTS TO REACH SFC.
WHILE ISOLATED CLICKS OF SMALL HAIL CANNOT BE RULED OUT IN
DEEPEST/MOST INTENSE CORES...OVERALL SVR POTENTIAL APPEARS TOO
CONDITIONAL AND MEAGER FOR EVEN MRGL PROBABILITIES ATTM.

...NEAR-COASTAL PAC NW...
MOISTURE-CHANNEL AND IR ANIMATIONS INDICATE SHORTWAVE TROUGH ABOUT
TO MOVE ASHORE.  SWATH OF LIGHTNING IS DETECTED ATTM INVOF S-CENTRAL
ORE COAST...AND SEPARATE AREA OF GLACIATED/LOW-TOPPED CONVECTION
APPEARS ON SATELLITE IMAGERY OFFSHORE NWRN ORE AND WA.  ACCOMPANYING
DESTABILIZATION WAS SAMPLED BY 12Z UIL RAOB THAT YIELDED AROUND 350
J/KG MUCAPE AND 200 J/KG MLCAPE...EXTENDING INTO ICING LAYERS
SUITABLE FOR LTG GENERATION DESPITE SFC TEMPS ONLY IN UPPER 40S F
THERE AND 50S OVER PAC WATERS.  THIS MRGLLY BUOYANT AIR MASS WILL
HELP TO MAINTAIN POTENTIAL FOR ISOLATED TO WIDELY SCATTERED THUNDER
FOR A FEW MORE HOURS...FOLLOWED BY RELATIVE LULL LASTING INTO
TONIGHT.  SECOND EPISODE OF THUNDER POTENTIAL MAY DEVELOP AFTER
ABOUT 06Z AS LOW-MIDDLE-LEVEL DESTABILIZATION AND MOISTURE TRANSPORT
OCCUR AHEAD OF NEXT NERN-PAC PERTURBATION.

..EDWARDS/COHEN.. 12/19/2014




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