DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 150533
SWODY1
SPC AC 150531

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1231 AM CDT SAT SEP 15 2012

VALID 151200Z - 161200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
A VIGOROUS SHORT WAVE TROUGH CENTERED ALONG THE ONTARIO/QUEBEC
BORDER TO THE LOWER GREAT LAKES WILL SHIFT E/NEWD TOWARDS THE
CANADIAN MARITIMES. ASSOCIATED SURFACE COLD FRONT SHOULD EXIT ALL
BUT ERN ME BY LATE MORNING. FARTHER SW...A PERSISTENT/ELONGATED
UPPER-LEVEL TROUGH CENTERED ALONG THE AZ/NM/SONORA/CHIHUAHUA BORDER
WILL GRADUALLY PIVOT EWD INTO THE SRN PLAINS BY EARLY SUN. A WEAK
SURFACE TROUGH WILL PERSIST FROM THE WRN GULF COAST TO TEXARKANA.

...ERN ME...
A BRIEF TIME WINDOW MAY EXIST FOR SURFACE-BASED TSTM DEVELOPMENT TO
OCCUR BEFORE THE AFOREMENTIONED COLD FRONT SWEEPS E OF THE STATE
AROUND NOON. GUIDANCE DIFFERS WITH TIMING OF THE FRONT...BUT THE
SLOWER SPECTRUM OF GUIDANCE SUCH AS THE NAM SUGGESTS WEAK HEATING
COULD YIELD SBCAPE NEAR 500 J/KG. ALTHOUGH FLOW WILL LARGELY
PARALLEL THE FRONT...STRONG DEEP-LAYER SPEED SHEAR MAY BE SUFFICIENT
FOR SMALL HAIL AND GUSTY WINDS.

...TEXARKANA...
SCATTERED AFTERNOON TSTMS SHOULD FORM ONCE AGAIN INVOF THE SURFACE
TROUGH AND CORRIDORS OF DIFFERENTIAL HEATING. LOW/MID-LEVEL FLOW IS
PROGGED TO REMAIN WEAK...BUT UPPER-LEVEL SWLYS SHOULD INTENSIFY AS A
JET STREAK EJECTS NEWD FROM FAR W TX. STILL WITHIN A POOR
MID/UPPER-LEVEL LAPSE RATE ENVIRONMENT...TSTMS SHOULD REMAIN PULSE
TO WEAKLY-ORGANIZED AND THE DAMAGING WIND THREAT DOES NOT APPEAR
SUFFICIENT TO WARRANT PROBABILITIES ATTM.

..GRAMS.. 09/15/2012

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