Friday, May 4, 2007

DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 040731
SWODY3
SPC AC 040730

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CDT FRI MAY 04 2007

VALID 061200Z - 071200Z

..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE UPPER
MIDWEST...MID MS VALLEY...CNTRL AND SRN PLAINS...

..UPPER MIDWEST/MID MS VALLEY/CNTRL AND SRN PLAINS...
A WESTERN U.S. UPPER-LEVEL TROUGH WILL DRIFT SLOWLY EWD INTO THE
HIGH PLAINS AS A COLD FRONT MOVES SEWD ACROSS THE MID MO VALLEY AND
SRN PLAINS REGIONS. SEVERAL MCS CLUSTERS WITH STRONG CONVECTION MAY
BE ONGOING AT THE BEGINNING OF THE PERIOD ALONG THIS FRONTAL
BOUNDARY. ALTHOUGH THUNDERSTORM COVERAGE SHOULD DECREASE IN THE
MORNING HOURS...MODEL FORECASTS CONTINUE TO BRING LARGE-SCALE ASCENT
EWD OVER THE COLD FRONT SUGGESTING SCATTERED TO NUMEROUS
THUNDERSTORMS MAY REDEVELOP SUNDAY AND SUNDAY NIGHT ALONG AND EAST
OF THE FRONT.

A MID-LEVEL JET ON THE ERN SIDE OF A HIGH PLAINS UPPER-LEVEL TROUGH
IS FORECAST TO LIFT NWD INTO THE NRN PLAINS SUNDAY AND THIS SHOULD
WEAKEN VERTICAL SHEAR PROFILES SOME ACROSS THE WARM SECTOR.
HOWEVER...ENOUGH INSTABILITY AND VERTICAL SHEAR SHOULD REMAIN
PRESENT SUNDAY AFTERNOON AND EVENING FOR THE DEVELOPMENT OF
SUPERCELLS. ATTM...MANY UNCERTAINTIES EXIST CONCERNING THE JET
STRUCTURE WITH THE UPPER-LEVEL TROUGH. IF SPEED MAXIMA WITH THE
MID-LEVEL JET MOVE NWD SLOWER THAN FORECAST BY THE MEDIUM RANGE
MODELS...A MORE SUBSTANTIAL THREAT FOR SUPERCELLS COULD EXIST ACROSS
PARTS OF THE REGION. HOWEVER...THE MOST VIABLE SOLUTION CONSIDERING
THE LINEAR FORCING ALONG THE COLD FRONT AND PARALLEL MID-LEVEL FLOW
SHOULD BE SQUALL-LINE DEVELOPMENT SUNDAY NIGHT ACROSS PARTS OF THE
MID-MO VALLEY AND SRN PLAINS REGION. AS CONFIDENCE INCREASES
CONCERNING THE UPPER-LEVEL TROUGH...LOW-LEVEL JET AND POSITION OF
THE COLD FRONT...MORE SPECIFIC SEVERE WEATHER THREAT AREAS SHOULD
BECOME IDENTIFIABLE IN LATER OUTLOOKS.

.BROYLES.. 05/04/2007

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