Friday, April 20, 2007

DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 200714
SWODY3
SPC AC 200713

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0213 AM CDT FRI APR 20 2007

VALID 221200Z - 231200Z

..THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE MID AND
LOWER MO VALLEY INTO UPPER MIDWEST...

..SYNOPSIS...

LATEST MODEL GUIDANCE IS IN GOOD AGREEMENT IN INDICATING THAT
NEGATIVELY TILTED MID-LEVEL TROUGH INITIALLY OVER THE CNTRL PLAINS
SUNDAY MORNING WILL DEAMPLIFY AS IT TRANSLATES NEWD INTO THE GREAT
LAKES...CRESTING RIDGE AXIS IN PLACE OVER THE ERN STATES. IN THE
LOW-LEVELS...PRIMARY SURFACE LOW OVER NERN SD IS EXPECTED TO DEVELOP
NEWD INTO CNTRL ONTARIO WITH A SECONDARY WAVE DEVELOPING ALONG
TRAILING COLD FRONT FROM S-CNTRL NEB INTO WRN WI BY MONDAY MORNING.

..MID/LOWER MO VALLEY INTO UPPER MIDWEST...

TSTMS /SLIGHTLY ELEVATED/ ARE EXPECTED TO BE ONGOING SUNDAY MORNING
ALONG FRONTAL ZONE FROM NRN MN SWWD THROUGH ERN SD INTO CNTRL
PORTIONS OF NEB/KS. SOME HAIL WILL BE POSSIBLE WITH THE MORE
INTENSE STORMS INITIALLY...ESPECIALLY THOSE OVER KS INTO NEB IN
CLOSER PROXIMITY TO UPPER TROUGH WHERE BOTH INSTABILITY AND FORCING
FOR ASCENT WILL BE STRONGER.

ADDITIONAL...SURFACE-BASED STORMS WILL INCREASE ALONG COLD FRONT BY
EARLY AFTERNOON OVER ERN PARTS OF SD/NEB INTO WRN MN/IA...PERHAPS
SWD INTO NERN KS AND NRN MO WITHIN MARGINALLY TO MODERATELY UNSTABLE
AIR MASS. FORECAST SOUNDINGS SUGGEST THAT VERTICAL SHEAR WILL BE
SUFFICIENTLY STRONG FOR ORGANIZED...SEVERE STORMS INCLUDING BOWS
AND/OR SUPERCELLS. THE PRIMARY SEVERE WEATHER THREAT APPEAR TO BE
DAMAGING WINDS AND LARGE HAIL...THOUGH ISOLATED TORNADOES ARE
POSSIBLE WITH ANY STORMS THAT CAN REMAIN MORE DISCRETE.

STORMS SHOULD QUICKLY MOVE/DEVELOP EWD/NEWD INTO WI AND NRN IL
SUNDAY NIGHT WITH A CONTINUING THREAT OF ISOLATED DAMAGING WINDS AND
SOME HAIL.

.MEAD.. 04/20/2007

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