Saturday, October 13, 2007

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 130538
SWODY2
SPC AC 130535

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1235 AM CDT SAT OCT 13 2007

VALID 141200Z - 151200Z

..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CENTRAL AND
SRN PLAINS...

..SYNOPSIS...
WHILE AN UPPER TROUGH IS FORECAST TO NEAR THE W COAST LATE...AND AN
UPPER LOW SLOWLY WILL CONTINUE MOVING NEWD ACROSS NEW ENGLAND INTO
THE CANADIAN MARITIMES....THE MAIN FEATURE WITH RESPECT TO THE
CONVECTIVE/SEVERE FORECAST THIS PERIOD WILL BE AN UPPER TROUGH
EJECTING FROM THE ROCKIES AND INTO THE PLAINS.

ASSOCIATED SURFACE LOW IS FORECAST TO MOVE EWD ACROSS KS/OK...WITH
TRAILING- COLD FRONT FORECAST TO MOVE EWD/SEWD ACROSS THE CENTRAL
AND SRN PLAINS THROUGH THE PERIOD.

..PARTS OF THE CENTRAL AND SRN PLAINS...
LARGE AREA OF STORMS SHOULD BE ONGOING AT THE START OF THE PERIOD
CENTERED ON NEB...WITHIN ZONE OF STRONG ISENTROPIC LIFT/WARM
ADVECTION N OF SURFACE WARM FRONT. THIS CONVECTION WILL LIKELY
CONTINUE THROUGH THE DAY...WITH A FEW STRONGER STORMS ON THE SRN
SIDE OF THE CONVECTIVE BAND POSSIBLY POSING A THREAT FOR MARGINAL
HAIL.

FURTHER S ALONG COLD FRONT FROM KS SWD INTO N CENTRAL TX...CAPPING
SHOULD SUPPRESS STORM DEVELOPMENT THROUGH MUCH OF THE AFTERNOON.
HOWEVER...COMBINATION OF DAYTIME HEATING/BOUNDARY-LAYER
MOISTENING/MIXING AND FOCUSED UVV ALONG APPROACHING COLD FRONT --
AIDED BY THE APPROACH OF THE UPPER TROUGH...SHOULD WEAKEN CAP
PROGRESSIVELY THROUGH THE AFTERNOON.

BY LATE AFTERNOON/EARLY EVENING...IT APPEARS THAT ISOLATED TO
SCATTERED STORM DEVELOPMENT WILL BEGIN ALONG THE COLD FRONT...AIDED
BY ROUGHLY 1000 J/KG MIXED-LAYER CAPE. UPON STORM
INITIATION...UPDRAFTS SHOULD RAPIDLY ORGANIZE -- AS AMPLE CAPE
COMBINED WITH 50 TO 60 KT SWLY FLOW AT MID-LEVELS SPREADING ATOP SLY
FLOW WITHIN THE WARM SECTOR BOUNDARY LAYER RESULTS IN AN ENVIRONMENT
SUPPORTIVE OF SUPERCELLS. WHILE STORMS SHOULD MOVE FAIRLY RAPIDLY
NEWD AWAY FROM THE FRONT...EWD EXTENT OF THREAT WILL BE LIMITED BY
STABILIZING AIRMASS DURING THE EVENING. ALONG WITH THE POTENTIAL
FOR LARGE HAIL AND LOCALLY-DAMAGING WINDS...AN ISOLATED TORNADO
COULD ALSO OCCUR AS SUFFICIENT LOW-LEVEL VEERING/SHEAR AND LOW LCLS
ARE EXPECTED.

AS LOW-LEVEL JET STRENGTHENS THROUGH THE EVENING/OVERNIGHT...STORMS
SHOULD INCREASE IN COVERAGE. HOWEVER...A SLOW DECREASE IN SEVERE
THREAT IS ANTICIPATED AS BOUNDARY LAYER STABILIZES.

.GOSS.. 10/13/2007

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