Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS01 KWNS 190513
SWODY1
SPC AC 190512

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1112 PM CST THU DEC 18 2014

VALID 191200Z - 201200Z

...NO SVR TSTM AREAS FORECAST...

...SUMMARY...
ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE TODAY ACROSS
CENTRAL TEXAS AND THE TEXAS GULF COAST EASTWARD TO THE MOUTH OF THE
MISSISSIPPI RIVER.

...SYNOPSIS...
A PROGRESSIVE FLOW REGIME OVER THE CONUS WILL FEATURE A SHORTWAVE
TROUGH SHEARING ENEWD AS IT MOVES FROM TX TO THE LOWER MS AND TN
RIVER VALLEYS.  IN THE LOW LEVELS...AN INFLECTION IN A WEAK FRONT
OVER THE NWRN GULF OF MEXICO WILL DEVELOP ENEWD FROM THE SHELF
WATERS OF THE MIDDLE TX COAST TO THE MOUTH OF THE MS RIVER.
ELSEWHERE...A SERIES OF WEAK DISTURBANCES WILL TRANSLATE EWD ACROSS
PARTS OF THE WRN U.S. AND NRN TIER OF STATES.

...TX COAST AND SRN LA...
THE AFOREMENTIONED SRN U.S. MID-LEVEL TROUGH WILL DEAMPLIFY DURING
THE DAY 1 PERIOD AND WILL LIKELY LIMIT SURFACE REFLECTION AND
CONSEQUENTLY...THE NWD PENETRATION OF A MODIFIED MARITIME AIR MASS
ACROSS THE UPPER TX COAST INTO SRN LA.  DEWPOINTS FROM BUOYS OVER
THE OPEN GULF S OF THE UPPER TX COAST/SRN LA ON THURSDAY EVENING
HAVE RISEN INTO THE MID TO UPPER 60S DEG F.  YET...ONLY A MODEST
STRENGTHENING IN SSWLY H85 FLOW /30 KT/ IS FORECAST AND SIGNIFICANT
QUESTION REMAINS WHETHER THE WARM SECTOR CAN PENETRATE INTO SRN LA
FROM THE IMMEDIATE SHELF WATERS GIVEN THE WEAK FRONTAL WAVE DEPICTED
IN MODEL GUIDANCE.  FORECAST SOUNDINGS SHOW AMPLE TROPOSPHERIC SHEAR
SUPPORTIVE FOR ORGANIZED STORMS BUT GENERALLY WEAK LAPSE RATES AND
MARGINAL MUCAPE /250-750 J PER KG/ WILL LIKELY LIMIT UPDRAFT
INTENSITY.  WHILE A STRONG STORM CANNOT BE ENTIRELY RULED OUT...THE
LACK OF AN APPRECIABLE SURFACE-BASED THUNDERSTORM THREAT PRECLUDES A
LOW CATEGORICAL THREAT OUTLOOK ATTM.

..SMITH/ROGERS.. 12/19/2014



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