Sunday, October 10, 2010

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 100521
SWODY1
SPC AC 100520

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1220 AM CDT SUN OCT 10 2010

VALID 101200Z - 111200Z

...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS SW OK/NW TX....

...SYNOPSIS...
IN ADVANCE OF POSITIVELY-TILTED SHORTWAVE TROUGH...HEIGHT FALLS ARE
FCST OVER PAC NW...SHUNTING NRN GREAT BASIN/NRN ROCKIES UPPER RIDGE
EWD. AS THIS OCCURS...CLOSED AND NEARLY CUT-OFF 500 MB CYCLONE --
NOW ANALYZED OVER SWRN SD/NWRN NEB AREA -- IS FCST TO MOVE SLOWLY
SWD ACROSS CENTRAL HIGH PLAINS...REACHING WRN KS BY 11/12Z.
ASSOCIATED SFC FRONTAL ZONE IS FCST TO REMAIN QUASISTATIONARY FROM
ERN KS ACROSS CENTRAL/SWRN OK THROUGH 11/00Z...BEFORE SRN SEGMENT
LOSES DEFINITION AMIDST STRONGER MESOSCALE BAROCLINICITY RESULTING
FROM CONVECTIVE/OUTFLOW PROCESSES. WRN SEGMENT OF FRONTAL ZONE OVER
PANHANDLE/SOUTH-PLAINS REGION MAY DRIFT SWD...ALONG WITH SFC LOW NOW
EVIDENT IN MESONET DATA SW PVW AND WNW LBB. MEANWHILE...OCCLUDED
SFC LOW OVER N-CENTRAL SD SHOULD WEAKEN IN FAVOR OF TRIPLE-POINT LOW
OVER SRN MN...WITH WARM FRONT EXTENDING ESEWD ACROSS WI/LM.

...SW OK/NW TX...
ISOLATED TO WIDELY SCATTERED TSTMS MAY BE ONGOING AT BEGINNING OF
PERIOD OVER PORTIONS SRN HIGH PLAINS...FROM TX/OK PANHANDLES INTO NW
OK...WITH MRGL THREAT FOR SVR HAIL. E AND S OF MORNING
ACTIVITY...AIR MASS ALONG AND JUST SE OF SFC FRONT WILL BECOME
PROGRESSIVELY MORE UNSTABLE THROUGHOUT LATE MORNING AND AFTERNOON.
ALTHOUGH SFC DEW POINTS ONLY ARE FCST IN 50S F...ABSOLUTE BOUNDARY
LAYER MOISTURE CONTENT WILL BE MRGL BUT SUFFICIENT TO SUPPORT
POTENTIAL FOR SCATTERED TSTMS IN WEAKLY CONVERGENT FRONTAL REGIME.
MLCAPE 500-1500 J/KG IS POSSIBLE WITHIN 10/21-11/00Z TIME
FRAME...ATOP WELL-MIXED SUBCLOUD LAYERS CONDUCIVE TO SUSTAINING HAIL
AND STG-SVR DOWNDRAFTS TO SFC.

SFC WINDS NEAR FRONTAL ZONE WILL BE WEAK...BUT ALSO BACKED
DIRECTIONALLY...AS PART OF REGIME OF STRENGTHENING/VEERING WITH
HEIGHT THAT RESULTS IN ENLARGED 0-3 KM AGL HODOGRAPHS. ENHANCED
BELT OF MIDLEVEL FLOW -- I.E. 30-40 KT AT 500 MB -- WILL CURVE
CYCLONICALLY THROUGH BASE OF TROUGH ACROSS TX PANHANDLE AND
OK...CONTRIBUTING TO FAVORABLE DEEP-LAYER SHEAR FOR STORM
ORGANIZATION. ACTIVITY IS EXPECTED TO GROW UPSCALE LATE AFTERNOON
INTO EVENING AND MOVE EWD ACROSS OK...SVR THREAT DIMINISHING AFTER
ABOUT 11/03Z AS DIABATIC SFC COOLING STABILIZES FOREGOING BOUNDARY
LAYER.

EXPECTED DENSITY OF CONVECTION OVER OUTLOOK AREA INDICATES
SUFFICIENT PROBABILITIES/COVERAGE OF AT LEAST MRGL SVR MAGNITUDES
FOR CATEGORICAL OUTLOOK.

..EDWARDS/ROGERS.. 10/10/2010

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