Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS03 KWNS 170828
SWODY3
SPC AC 170827

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0227 AM CST WED DEC 17 2014

VALID 191200Z - 201200Z

...THERE IS A MRGL RISK OF SVR TSTMS NEAR THE GULF COAST FRIDAY
THROUGH FRIDAY NIGHT....

...SUMMARY...
STRONG THUNDERSTORMS ARE EXPECTED ACROSS THE GULF COAST STATES
FRIDAY THROUGH FRIDAY NIGHT.  IT IS POSSIBLE THAT SOME OF THESE
COULD BECOME CAPABLE OF PRODUCING SEVERE WIND GUSTS AND PERHAPS
ISOLATED TORNADOES...ESPECIALLY NEAR IMMEDIATE COASTAL AREAS.

...SYNOPSIS/GULF COAST STATES...
ALTHOUGH MODELS SUGGEST THAT THE STRONG ZONAL FLOW ACROSS THE
MID-LATITUDE PACIFIC WILL TRANSITION TO A MORE AMPLIFIED REGIME
...LITTLE CHANGE IN THE UPPER PATTERN IS EXPECTED FROM THURSDAY
THROUGH FRIDAY ACROSS MUCH OF NORTH AMERICA.  SHORT WAVES WITHIN THE
SPLIT BELT OF WESTERLIES SHOULD REMAIN PROGRESSIVE...INCLUDING ONE
FORECAST TO ACCELERATE EAST NORTHEAST OF THE TEXAS BIG BEND
REGION...THROUGH THE LOWER MISSISSIPPI VALLEY BY 12Z SATURDAY.

FORCING ASSOCIATED WITH THIS IMPULSE PROBABLY WILL SUPPORT A
DEVELOPING WAVE ALONG A REMNANT SURFACE FRONTAL ZONE EXTENDING
ACROSS THE NORTHERN GULF OF MEXICO AND MIDDLE TEXAS COAST...INTO THE
LOWER RIO GRAND VALLEY.  HOWEVER...GIVEN THE DRY/POTENTIALLY COLD
BOUNDARY LAYER LIKELY TO BE PRESENT TO THE NORTH OF THE FRONT...AS
WELL AS ACROSS THE NORTHEASTERN GULF OF MEXICO...IT APPEARS
INCREASINGLY PROBABLE THAT THIS WAVE DEVELOPMENT WILL REMAIN WEAK.
NO FURTHER AMPLIFICATION OF THE UPPER IMPULSE IS
EXPECTED...AND...WITH TIME...STRONGER MID-LEVEL FORCING IS GENERALLY
FORECAST TO GRADUALLY SHIFT TO THE NORTH...AWAY FROM THE SURFACE
FRONT.  AS THIS OCCURS...THOUGH...AFTER MIGRATING ACROSS MID/UPPER
TEXAS COASTAL AREAS...THE SURFACE LOW CENTER MAY TRACK INLAND OF THE
CENTRAL GULF COAST.

WITH LITTLE APPRECIABLE STEEPENING OF MID-LEVEL LAPSE RATES EXPECTED
ACROSS MUCH OF THE IMMEDIATE GULF COAST REGION...AND BOUNDARY LAYER
MOISTENING OVER THE WESTERN GULF OF MEXICO REMAINING RELATIVELY
MODEST...ANY DESTABILIZATION SHOULD BE WEAK.  HOWEVER...WITH EVEN
WEAK WARM SECTOR BOUNDARY LAYER DESTABILIZATION...THE ENVIRONMENT
MAY BECOME AT LEAST MARGINALLY CONDUCIVE TO ORGANIZED SEVERE
CONVECTION...INCLUDING SUPERCELLS.  DEEP LAYER SHEAR SHOULD BE
SUFFICIENT...WITH WIND FIELDS CHARACTERIZED BY 30-40 KT
SOUTH/SOUTHWESTERLY 850 MB FLOW VEERING TO WESTERLY AT 50-70 KT
AROUND 500 MB.

..KERR.. 12/17/2014



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