Saturday, April 19, 2008

DAY48SVR: Nws Storm Prediction Center Norman Ok

ACUS48 KWNS 190903
SWOD48
SPC AC 190902

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0402 AM CDT SAT APR 19 2008

VALID 221200Z - 271200Z

...DISCUSSION...

SOME THREAT FOR STRONG TO SEVERE STORMS MAY EXIST TUESDAY DAY 4 IN
ASSOCIATION WITH SHORTWAVE TROUGH AND ATTENDANT COLD FRONT EJECTING
ENEWD THROUGH THE GREAT LAKES AND NRN OH VALLEY. HOWEVER...POTENTIAL
FOR WIDESPREAD CLOUDS AND ONGOING STORMS LENDS UNCERTAINTY REGARDING
THE DEGREE OF INSTABILITY AND OVERALL SEVERE POTENTIAL. OTHER STORMS
MIGHT DEVELOP FARTHER SOUTH AND SOUTHWEST ALONG THE COLD FRONT FROM
THE OH VALLEY INTO TX. HOWEVER...HEIGHT RISES IN WAKE OF LEAD WAVE
AND TENDENCY FOR THE MOIST WARM SECTOR TO REMAIN SOUTH OF THE
STRONGER UPPER FLOW LOWERS CONFIDENCE IN OVERALL EXTENT OF SEVERE
THREAT.

BEYOND DAY 4...MODELS BEGIN TO DIVERGE WITH THE ECMWF AMPLIFYING A
STRONGER WAVE INTO THE GREAT BASIN VERSUS THE MORE ZONAL PATTERN
WITH THE GFS. IN EITHER CASE...THE FRONT MAY BEGIN TO RETREAT NWD
THROUGH TX...AND MODELS SUGGEST A SRN STREAM WAVE COULD INTERACT
WITH THIS BOUNDARY. SOME THREAT FOR SEVERE STORMS WILL EXIST ACROSS
TX IN VICINITY OF THE FRONT AS WELL AS FARTHER NORTH WITHIN WARM
ADVECTION REGIME OVER OK. HOWEVER...WEAK AMBIENT UPPER FLOW AND
TENDENCY FOR THE MODELS TO BEGIN TO DIVERGE SUGGEST CONFIDENCE IS
NOT HIGH ENOUGH TO INTRODUCE AN AREA AT THIS TIME.

BEYOND DAY 5...SIGNIFICANT DISPERSION IN THE MREF...ECMWF AND GFS
SUGGESTS PREDICTABILITY IS TOO LOW TO INTRODUCE AN AREA THIS
FORECAST PERIOD.

..DIAL.. 04/19/2008

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