DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 281957
SWODY1
SPC AC 281955

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0255 PM CDT SAT SEP 28 2013

VALID 282000Z - 291200Z

...NO SVR TSTM AREAS FORECAST...

TWO CHANGES HAVE BEEN MADE TO THE OUTLOOK FOR THIS ISSUANCE. THE
FIRST CHANGE IS TO TRIM THE WRN EDGE OF THE 5 PERCENT WIND DAMAGE
PROBABILITY TO ACCOUNT FOR THE ERN MOVEMENT OF CONVECTION ONGOING IN
NE TX AND SE OK. THE SECOND CHANGE IS TO TRIM THE WRN EDGE OF THE
THUNDERLINE FROM THE SRN PLAINS NEWD INTO THE MID-MO VALLEY.

..BROYLES.. 09/28/2013

.PREV DISCUSSION... /ISSUED 1040 AM CDT SAT SEP 28 2013/

...CENTRAL TX NEWD INTO THE MID MS VALLEY THROUGH THIS EVENING...
IN ADVANCE OF A SEWD-MOVING COLD FRONT...MODEST DIURNAL HEATING OF A
MOIST AIR MASS SHOULD YIELD 500-1000 J/KG WITH LITTLE MLCINH.
FRONTAL ASCENT AND PRECEDING WEAK WARM ADVECTION WILL SUPPORT
SCATTERED STORMS WITHIN A WEAKLY SHEARED ENVIRONMENT. GPS PW VALUES
AROUND 2 INCHES SUGGEST PRECIPITATION LOADING MAY BE SUFFICIENT FOR
ISOLATED MARGINALLY SVR WIND GUSTS WHERE ADEQUATE BUOYANCY EXISTS
FROM CENTRAL TX NEWD INTO ERN OK AND WRN AR. FARTHER NE INTO THE MID
MS VALLEY...MARKEDLY LOWER BUOYANCY WILL EXIST OWING TO A DRIER
BOUNDARY LAYER AHEAD OF THE FRONT AND/OR CONVECTION WITH RELATED
CLOUDS OUTPACING THE DEEPER FRONTAL CIRCULATION DESPITE STRONGER
DEEP SHEAR.

...PACIFIC NW COAST THIS AFTERNOON AND EVENING...
MINIMAL BUOYANCY WILL GLANCE THE COAST WITHIN THE WARM CONVEYOR BELT
AND ONSHORE-FLOW REGIME AHEAD OF A LARGE E-PACIFIC CYCLONE. STRONG
FORCING FOR ASCENT WITHIN THIS REGIME COULD SUPPORT LOW-TOPPED
CONVECTIVE BANDS SPREADING INLAND FROM THE COASTAL WATERS.
WIDESPREAD INLAND CLOUDS/PRECIPITATION WILL LARGELY MITIGATE ANY
SUBSTANTIVE BUOYANCY FROM ENSUING. HOWEVER...A WSWLY LLJ WITH 850-MB
SPEEDS INCREASING AOA 50 KT MAY SUPPORT AN ISOLATED SVR WIND GUST OR
TWO OWING TO VERTICAL MOMENTUM TRANSPORT WITHIN LINE-EMBEDDED
CONVECTIVE ENHANCEMENTS.

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