Tuesday, October 19, 2010

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 190600
SWODY1
SPC AC 190559

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CDT TUE OCT 19 2010

VALID 191200Z - 201200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
WHILE A LARGE TROUGH OVER THE ERN U.S. AMPLIFIES FURTHER THIS
PERIOD...A FAIRLY POTENT UPPER LOW INITIALLY OFF THE SRN CA COAST IS
PROGGED TO MOVE STEADILY EWD TOWARD/INTO NRN BAJA CA/SRN CA.

AT THE SURFACE...WEAK LOW PRESSURE IS FORECAST TO LINGER OVER SRN
CA...WHILE FARTHER E A COLD FRONT ASSOCIATED WITH THE DEEPENING ERN
TROUGH SAGS STEADILY SSEWD ACROSS THE SOUTHEAST/SRN PLAINS THROUGH
THE PERIOD.

...CENTRAL AND NERN TX/SERN OK EWD INTO SRN AR/NRN LA...
ELEVATED STORMS SHOULD BE ONGOING AT THE START OF THE PERIOD ACROSS
PARTS OF OK AND AR AND INTO N TX...NEAR AND N OF THE COLD FRONT
MOVING SLOWLY SSEWD ACROSS THIS REGION. AFTERNOON DESTABILIZATION
AHEAD OF THE FRONT /ON THE ORDER OF 500 TO 1000 J/KG MIXED-LAYER
CAPE NEAR PEAK HEATING/ SHOULD SUPPORT A CONVECTIVE
INCREASE...INCLUDING THE POTENTIAL FOR SCATTERED SURFACE-BASED
DEVELOPMENT NEAR THE FRONT.

WITH WEAK LOW-LEVEL FLOW EXPECTED BUT MODERATE NWLYS AT MID
LEVELS...SHEAR MAY BE SUFFICIENT TO SUPPORT ISOLATED ORGANIZED
STORMS...WITH SMALL HAIL THE MAIN THREAT. A FEW OF THE STRONGEST
STORMS COULD PRODUCE MARGINALLY-SEVERE HAIL OR EVEN AN ISOLATED
STRONGER WIND GUST...BUT ATTM THREAT DOES NOT APPEAR SUFFICIENT TO
WARRANT SLIGHT RISK UPGRADE.

...SRN CA...
DAYTIME HEATING COMBINED WITH COOL MID-LEVEL TEMPERATURES ASSOCIATED
WITH THE UPPER LOW SHOULD YIELD MODEST BUT SUFFICIENT
DESTABILIZATION TO FUEL A DIURNAL INCREASE IN CONVECTION. WHILE THE
DEGREE OF INSTABILITY SHOULD REMAIN GENERALLY INSUFFICIENT FOR
SUBSTANTIAL SEVERE POTENTIAL...MODERATELY-STRONG SELY FLOW ALOFT MAY
PERMIT A FEW LONGER-LIVED STORMS TO EVOLVE. WITH COOL AIR ALOFT
POSSIBLY SUPPORTING MARGINALLY-SEVERE HAIL WITH ONE OR TWO OF THE
STRONGER CELLS...OR EVEN A BRIEF TORNADO GIVEN ENHANCED AMBIENT
ENVIRONMENTAL VORTICITY INVOF THE UPPER CIRCULATION CENTER...WILL
INTRODUCE LOW SEVERE PROBABILITIES ACROSS THIS REGION.

..GOSS/GRAMS.. 10/19/2010

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