DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 291219
SWODY1
SPC AC 291217

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0717 AM CDT SAT SEP 29 2012

VALID 291300Z - 301200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
MORNING SATELLITE IMAGERY SHOWS AN UPPER TROUGH POSITIONED OVER THE
NERN QUARTER OF THE CONUS...WITH AN EMBEDDED IMPULSE DIGGING SEWD
TOWARD THE MID OH VALLEY. MODEL GUIDANCE INDICATES THIS IMPULSE WILL
PROGRESS EWD TOWARD THE MID-ATLANTIC REGION LATER IN THE DAY...WHICH
WILL CAUSE A SURFACE COLD FRONT OVER THE CAROLINAS TO ACCELERATE
OFFSHORE BY THE END OF THE FORECAST PERIOD. MEANWHILE...A
DISORGANIZED UPPER TROUGH OVER NM/TX IS FORECAST TO BECOME BETTER
DEFINED LATER TONIGHT. AS THIS OCCURS...ASSOCIATED SURFACE LOW
PRESSURE LOCATED OVER THE EDWARDS PLATEAU THIS MORNING WILL MOVE
INTO ERN TX.

...WRN GULF COAST REGION...
DISORGANIZED MCS HAS BEEN MOVING EWD ACROSS SRN TX DURING THE EARLY
MORNING HOURS...WITH WARM ADVECTION SHOWERS/THUNDERSTORMS SPREADING
NWD OVER THE TX/LA GULF COAST AHEAD OF THE MCS. THESE STORMS ARE
EMBEDDED WITHIN A VERY MOIST AIRMASS...CHARACTERIZED BY SURFACE
DEWPOINTS IN THE LOW 70S AND PW VALUES FROM 2.0-2.25 INCHES.
HOWEVER...LOW AND MIDLEVEL LAPSE RATES ARE VERY WEAK...WHICH WILL
LIMIT MUCAPE VALUES TO LESS THAN 1000 J/KG THROUGHOUT THE FORECAST
PERIOD.

DURING THE DAY TIME HOURS...AN ISOLATED STRONG TO SVR DOWNBURST WILL
BE POSSIBLE WITH STRONGER UPDRAFT CORES...GIVEN THE VERY MOIST
AIRMASS. BY EVENING/NIGHT...AN UPPER TROUGH WILL BECOME BETTER
DEFINED OVER TX...AND SURFACE LOW PRESSURE WILL PROGRESS E-NEWD
ACROSS SRN INTO ERN TX. THIS MAY LEAD TO THE DEVELOPMENT OF ANOTHER
NOCTURNAL MCS MOVING ACROSS THE TX GULF COAST REGION. IN ADDITION TO
AN ISOLATED DAMAGING WIND GUST THREAT...THE POTENTIAL FOR A BRIEF
TORNADO WILL ALSO EXIST AS LOW-LEVEL WINDS AND VERTICAL SHEAR
STRENGTHEN SLIGHTLY TONIGHT.

...CAROLINAS...FAR ERN GA...
IR SATELLITE IMAGERY SHOWS CLOUD COVER SPREADING EWD ACROSS NC THIS
MORNING...WHICH WILL LIMIT HEATING AND BOUNDARY LAYER
DESTABILIZATION DURING THE DAY. DESPITE MARGINAL DESTABILIZATION AND
SUBSEQUENT WEAK CAPE VALUES OVER NC...MODERATE DEEP-LAYER WLY WINDS
AND STRONG FORCING FOR ASCENT ARE FORECAST TO OCCUR OVER THE AREA AS
AN UPPER DISTURBANCE APPROACHES THIS AFTERNOON/EVENING. THIS COULD
AID IN THE DEVELOPMENT OF ISOLATED STRONG/SVR MULTICELLS CAPABLE OF
PRODUCING DAMAGING WIND GUSTS. FARTHER S OVER SC AND FAR ERN
GA...CLOUD COVER WILL BE LESS...WHICH WILL PROMOTE STRONGER HEATING
AND STEEP LOW-LEVEL LAPSE RATES BY AFTERNOON. THIS THERMODYNAMIC
ENVIRONMENT MAY SUPPORT AN ISOLATED DAMAGING WIND THREAT AS ISOLATED
TO SCATTERED THUNDERSTORMS DEVELOP.

..GARNER/THOMPSON.. 09/29/2012

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