Saturday, June 9, 2007

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 091731
SWODY2
SPC AC 091729

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1229 PM CDT SAT JUN 09 2007

VALID 101200Z - 111200Z

..THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE CNTRL AND NRN
PLAINS THROUGH THE MID AND UPPER MS VALLEY...

..SYNOPSIS...

LARGE SCALE UPPER RIDGE WILL GRADUALLY BUILD OVER THE CNTRL-NRN
PLAINS AND UPPER MS VALLEY SUNDAY AS UPSTREAM TROUGH AMPLIFIES OVER
THE NWRN STATES. HOWEVER...POTENTIAL WILL EXIST FOR A SERIES OF WEAK
IMPULSES TO ROTATE ALONG NRN PERIPHERY OF UPPER RIDGE. WARM FRONT
NOW EXTENDING FROM OK SEWD INTO THE LOWER MS VALLEY WILL LIFT
RAPIDLY NWD INTO THE NRN PLAINS AND UPPER MS VALLEY SUNDAY. A LEE
TROUGH/DRYLINE WILL BECOME ESTABLISHED FROM THE CNTRL THROUGH NRN
PLAINS.


..CNTRL AND NRN PLAINS THROUGH MID AND UPPER MS VALLEY AREAS...

THE ATMOSPHERE WILL RAPIDLY DESTABILIZE IN THIS REGION SOUTH OF WARM
FRONT AS UPPER 60S DEWPOINTS ADVECT NWD BENEATH MODERATELY STEEP MID
LEVEL LAPSE RATES. AXIS OF MLCAPE FROM 2500 TO 3000 J/KG WILL LIKELY
DEVELOP EAST OF DRYLINE. PRIMARY LIMITING FACTOR WILL BE TENDENCY
FOR UPPER RIDGE TO BUILD OVER THE AREA...WHICH WILL TEND TO WEAKEN
MAGNITUDE OF MID LEVEL FLOW AND DEEP LAYER SHEAR AS WELL AS IMPLY
POTENTIAL FOR LARGE SCALE SUBSIDENCE. BUILDING UPPER RIDGE MAY ALSO
LIMIT CONVECTIVE COVERAGE AND DECREASES OVERALL CONFIDENCE IN WHERE
STORMS ARE MOST LIKELY TO DEVELOP.

SOME STORMS MAY BE IN PROGRESS EARLY SUNDAY MOST LIKELY FROM SERN
NEB TROUGH ERN KS/WRN MO WITHIN ZONE OF ASCENT ON NOSE OF SWLY LOW
LEVEL JET. THREAT FOR MAINLY HAIL MAY EXIST WITH THESE STORMS. SOME
POSSIBILITY EXIST THAT THESE STORMS COULD BECOME SURFACE BASED AND
CONTINUE INTO PARTS OF ERN KS/MO AS THE BOUNDARY LAYER DESTABILIZES.
OTHERWISE...WEAK DISTURBANCES MOVING THROUGH NRN PERIPHERY OF UPPER
RIDGE AND WEAK DRYLINE/LEE TROUGH CONVERGENCE WILL PROVIDE AT LEAST
A SLIGHT CHANCE FOR STORMS TO DEVELOP SUNDAY AFTERNOON OVER THE NRN
AND CNTRL PLAINS AS THE CAP WEAKENS. DEEP SHEAR FORECAST TO BE
AROUND 30 KT WILL BE AT LEAST MARGINALLY SUFFICIENT OF SOME ROTATING
UPDRAFTS...ESPECIALLY GIVEN THE EXPECTED STRONG INSTABILITY WHICH
WILL HELP TO AMPLIFY VORTICITY. HOWEVER...WEAKENING FLOW ALOFT
SUGGEST STORMS SHOULD REMAIN OUTFLOW DOMINANT WITH ISOLATED LARGE
HAIL AND DAMAGING WIND GUSTS BEING THE PRIMARY THREATS. OTHER STORMS
MAY BE POSSIBLE NEAR THE E-W BOUNDARY FROM EXTREME NRN ND EWD
THROUGH NRN MN.

SOME OPPORTUNITY WILL EXIST FOR A FEW STORMS TO DEVELOP OVERNIGHT
ALONG NOSE OF STRENGTHENING SWLY LOW LEVEL JET FROM ERN PORTIONS OF
THE CNTRL/NRN PLAINS INTO THE MID-UPPER MS VALLEY. IF STORMS
DEVELOP...THEY WILL LIKELY BE SLIGHTLY ELEVATED WITHIN A WEAK SHEAR
ENVIRONMENT. HOWEVER...EXPECTED THERMODYNAMIC PROFILES WILL SUPPORT
A THREAT FOR MAINLY LARGE HAIL...AND POSSIBLY ISOLATED DAMAGING WIND
GUSTS.


..SC THROUGH SERN NC...

RESIDUAL LOW LEVEL MOISTURE IN POST FRONTAL REGIME WILL CONTRIBUTE
TO MODERATE INSTABILITY AS THE BOUNDARY LAYER WARMS DURING THE
AFTERNOON. HOWEVER...FORECAST SOUNDINGS SHOW AN INVERSION IN THE
700-500 MB LAYER...LIKELY DUE TO SUBSIDENCE...WHICH WILL LIMIT MID
LEVEL LAPSE RATES. BELT OF 30 KT NWLY MID LEVEL WINDS BENEATH ENELY
LOW LEVEL FLOW MAY RESULT IN SUFFICIENT DEEP SHEAR FOR ORGANIZED
MULTICELLS. SOME POTENTIAL WILL ONCE AGAIN EXIST FOR A FEW STORMS TO
DEVELOP WITHIN THE WEAKLY CAPPED ENVIRONMENT AND SPREAD SEWD WITHIN
THE NWLY FLOW REGIME. ISOLATED DOWNBURSTS AND MARGINALLY SEVERE HAIL
WILL BE POSSIBLE WITH THE STRONGER STORMS.

.DIAL.. 06/09/2007

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