Saturday, November 12, 2011

DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 120834
SWODY3
SPC AC 120833

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0233 AM CST SAT NOV 12 2011

VALID 141200Z - 151200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF E TX...

...SYNOPSIS...
STRONG SRN STREAM SHORT-WAVE TROUGH CROSSING NRN MEXICO/NM/FAR W TX
IS PROGGED TO CONTINUE MOVING QUICKLY EWD THIS PERIOD...AND SHOULD
APPROACH THE MID AND LOWER MS VALLEY REGION BY THE END OF THE
PERIOD. MEANWHILE...WITH THIS SYSTEM ROUGHLY PHASED WITH A TROUGH
IN THE NRN STREAM...THE RESULTANT WILL BE A LARGE COMPOSITE TROUGH
AFFECTING MOST OF THE COUNTRY BY THE END OF THE PERIOD.

DIFFERENCES IN TIMING AND EVOLUTION OF THE UPPER SYSTEM BETWEEN THE
NAM AND GFS RESULT IN SIMILAR DIFFERENCES IN SURFACE PATTERN.
GENERALLY HOWEVER...BOTH MODELS DEPICT A WEAK LOW INVOF THE ARKLATEX
DURING THE LATE AFTERNOON...WITH A WEAK TRAILING FRONT EXTENDING
ACROSS E TX. THE MAIN CONVECTIVE THREAT THIS PERIOD WILL EVOLVE IN
CONJUNCTION WITH THIS SURFACE SYSTEM...AND THE ASSOCIATED SRN STREAM
TROUGH CROSSING THE AREA.

...E TX...
PERSISTENT NWD ADVECTION OF LOW-LEVEL MOISTURE IS EXPECTED INTO E
TX...AND TO SOME DEGREE EWD INTO THE CENTRAL GULF COAST REGION...AS
THE APPROACHING UPPER TROUGH SUPPORTS A WEAK SURFACE CYCLOGENESIS
OVER THE ARKLATEX REGION DURING THE AFTERNOON. THIS COMBINED WITH
SOME COOLING ALOFT WITH THE APPROACH OF THE UPPER TROUGH SUGGESTS
WEAK DESTABILIZATION ACROSS E TX AND ADJACENT AREAS AHEAD OF THE
SURFACE FRONT -- SUPPORTIVE OF AFTERNOON SHOWER/THUNDERSTORM
DEVELOPMENT.

THOUGH MODEL UNCERTAINTY RAISES QUESTIONS WITH RESPECT TO POTENTIAL
TIMING/LOCATION/INTENSITY OF THE CONVECTION...IT APPEARS ATTM THAT
THE DEGREE OF INSTABILITY COMBINED WITH SUFFICIENTLY STRONG SWLY
FLOW ALOFT SHOULD SUPPORT SOME SEVERE POTENTIAL. WHILE SUPERCELLS
WOULD BE POSSIBLE...LINEAR EVOLUTION WITH TIME APPEARS LIKELY...AND
ASSOCIATED THREATS FOR WIND/HAIL APPEAR SUFFICIENT TO SUPPORT THE
INTRODUCTION OF A SLIGHT RISK FORECAST ATTM. THREAT WILL SHIFT EWD
WITH TIME...WITH SOME RISK POSSIBLY SPREADING AS FAR E AS THE
CENTRAL GULF COAST REGION LATE.

..GOSS.. 11/12/2011

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