Sunday, May 16, 2010

DAY48SVR: Nws Storm Prediction Center Norman Ok

ACUS48 KWNS 160857
SWOD48
SPC AC 160857

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0357 AM CDT SUN MAY 16 2010

VALID 191200Z - 241200Z

THE MEDIUM RANGE MODELS ARE IN GENERAL AGREEMENT EARLY IN THE DAY 4
TO 8 PERIOD WITH AN UPPER-LEVEL SYSTEM MOVING EWD ACROSS THE
ROCKIES. IN RESPONSE...LOW-LEVEL FLOW SHOULD INCREASE ACROSS THE SRN
PLAINS WITH A LARGE AREA OF MODERATE TO STRONG INSTABILITY POSSIBLE
WEDNESDAY AFTERNOON/DAY 4 ACROSS MUCH OF THE SRN PLAINS. IN
ADDITION...MODEL FORECASTS SUGGEST THAT DEEP LAYER SHEAR ACROSS THE
WARM SECTOR WILL BE SUFFICIENT FOR ORGANIZED STORMS. IF THIS
UPPER-LEVEL PATTERN MATERIALIZES...SEVERE THUNDERSTORM DEVELOPMENT
WOULD BE POSSIBLE WEDNESDAY AND WEDNESDAY NIGHT FROM WRN KS SSEWD
ACROSS WRN AND CNTRL OK AS A DRYLINE ORGANIZES AND MOVES EWD ACROSS
THE REGION. HOWEVER...THE SYSTEM APPEARS A BIT TOO WEAK TO WARRANT
AN OUTLOOK AREA. THE ECMWF AND GFS CONTINUE IN GOOD AGREEMENT MOVING
THE UPPER-LEVEL TROUGH EWD ACROSS THE SRN PLAINS THURSDAY/DAY 5 AND
INTO THE MID-MS VALLEY ON FRIDAY/DAY 6. STRONG THUNDERSTORMS WOULD
BE POSSIBLE IN THE ARKLATEX REGION THURSDAY AND IN THE OH AND TN
VALLEYS FRIDAY JUST AHEAD OF THE UPPER-LEVEL TROUGH. BY SATURDAY/DAY
7 AND SUNDAY/DAY 8...THE MODELS DEVELOP A HIGHLY MERIDIONAL
UPPER-LEVEL TROUGH IN THE WRN STATES BUT ARE SIGNIFICANTLY VARIANT
ON THE TIMING WITH THE GFS MUCH FASTER THAN THE ECMWF. AHEAD OF THIS
SYSTEM...A BROAD LOW-LEVEL JET WOULD RESULT IN A LARGE WARM SECTOR
ACROSS THE GREAT PLAINS WITH A POSSIBLE SEVERE EVENT IN THE CNTRL
PLAINS/MID-MO VALLEY ON SATURDAY. HOWEVER...MUCH UNCERTAINTY EXISTS
CONCERNING THE TIMING OF THE UPPER-LEVEL SYSTEM AND A SEVERE THREAT
AREA CAN NOT BE DRAWN ATTM.

..BROYLES.. 05/16/2010

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