Tuesday, September 25, 2007

DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 250731
SWODY3
SPC AC 250729

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0229 AM CDT TUE SEP 25 2007

VALID 271200Z - 281200Z

..NO SVR TSTM AREAS FORECAST...

..SYNOPSIS...
PROGRESSIVE UPPER PATTERN IS FORECAST THIS PERIOD...AS A TROUGH
CONTINUES MOVING ACROSS THE ERN CONUS WHILE UPSTREAM RIDGE MOVES OUT
OF THE ROCKIES AND INTO THE CENTRAL CONUS. FURTHER UPSTREAM...THE
LOW WHICH HAS LINGERED OFF THE CA COAST IS FORECAST TO BECOME
ABSORBED WITHIN A TROUGH MOVING SEWD FROM THE GULF OF AK INTO THE
WRN STATES.

AT THE SURFACE...A COLD FRONT WILL MOVE ACROSS THE PAC NW AHEAD OF
THE DEVELOPING WRN TROUGH...WHILE IN THE EAST A WEAKENING FRONT MAY
LINGER INVOF THE ATLANTIC SEABOARD THROUGH MUCH OF THE PERIOD.

..WRN OK INTO THE OK/TX PANHANDLES AND WRN N TX...
MARGINALLY-UNSTABLE AIRMASS IS FORECAST TO DEVELOP DURING THE
AFTERNOON AS DAYTIME HEATING COMBINES WITH MODESTLY-MOIST BOUNDARY
LAYER TO YIELD AROUND 1000 J/KG MIXED-LAYER CAPE. WHILE LARGE-SCALE
RIDGING IS FORECAST TO GENERALLY SUPPRESS CONVECTION...MODELS HINT
THAT A WEAK SHORT-WAVE TROUGH MAY CROSS PARTS OF THE SRN HIGH PLAINS
WHICH -- ALONG WITH WEAK SELY LOW-LEVEL UPSLOPE FLOW -- COULD AID IN
THE DEVELOPMENT A OF FEW STORMS. IF A FEW STORMS CAN
DEVELOP...LOW-LEVEL SELYS BENEATH 25 KT WNWLYS AT MID-LEVELS MAY
PROVIDE SHEAR SUFFICIENT FOR WEAKLY-ROTATING UPDRAFTS...AND
ASSOCIATED/LOW-END SEVERE THREAT. THUS...WILL INTRODUCE
5%/CONDITIONAL SEVERE PROBABILITIES ACROSS THIS REGION.

.GOSS.. 09/25/2007

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