SPC AC 250728
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0228 AM CDT THU MAY 25 2006
VALID 271200Z - 281200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MODELS AGREE THAT PATTERN WILL TRANSITION TO AN UPPER RIDGE IN THE
ERN U.S. WITH AN UPPER TROUGH AMPLIFYING IN THE W. BETWEEN THESE TWO
FEATURES THE NRN PLAINS WILL BE UNDER THE INFLUENCE OF SWLY FLOW
ALOFT. A NE-SW ORIENTED COLD FRONT WILL MOVE SLOWLY EWD INTO THE NRN
PLAINS. THE POTENTIAL WILL EXIST FOR A SERIES OF VORTICITY MAXIMA TO
ROTATE NEWD OUT OF THE UPPER TROUGH INTO THE NRN PLAINS IN VICINITY
OF THE FRONT. SUBTLE DIFFERENCES DO EXIST BETWEEN THE MODELS WITH
THE ECMWF BEING A LITTLE FARTHER W WITH THE UPPER TROUGH RESULTING
IN HEIGHT RISES OVER THE NRN PLAINS ON SATURDAY.
...NRN PLAINS...
A STRONG LOW LEVEL JET WILL DEVELOP E OF LEE TROUGH THAT WILL BECOME
ESTABLISHED OVER THE PLAINS DOWNSTREAM FROM AMPLIFYING UPPER TROUGH.
THIS WILL CONTRIBUTE TO THE NWD ADVECTION OF LOW LEVEL MOISTURE INTO
THE NRN PLAINS BENEATH STEEP LAPSE RATES. MODERATE INSTABILITY IS
EXPECTED WITHIN THE PRE-FRONTAL WARM SECTOR ACROSS THE DAKOTAS. ONE
CONCERN IS POSSIBILITY FOR A STRONG CAP GIVEN PRESENCE OF SWLY
700-500 MB FLOW DOWNSTREAM FROM UPPER TROUGH WHICH WILL HAVE THE
POTENTIAL TO ADVECT THE EML EWD INTO THE NRN PLAINS. ANOTHER CONCERN
IS HOW MUCH HEIGHTS WILL RISE OVER THE NRN PLAINS DOWNSTREAM FROM
AMPLIFYING UPPER TROUGH. THE ECMWF HAS BEEN FARTHER W WITH THE WRN
U.S. UPPER TROUGH...RESULTING IN MORE RIDGINESS AND HEIGHT RISES
OVER THE NRN PLAINS. THIS WOULD TEND TO KEEP ANY IMPULSES ROTATING
THROUGH THE UPPER TROUGH W OF THE WARM SECTOR AND SUPPORT MORE POST
FRONTAL CONVECTION. THE GFS AND NAM ARE FARTHER EAST WITH THE UPPER
TROUGH WITH MORE SWLY FLOW AND LESS OF A RIDGE OVER THE NRN PLAINS.
THESE SOLUTIONS WOULD SUPPORT A BETTER SEVERE POTENTIAL THAN THE
ECMWF. GIVEN THE MODEL DIFFERENCES AND POTENTIAL FOR A STRONG
CAP...WILL KEEP 5% SEVERE PROBABILITIES AT THIS TIME. HOWEVER...A
SLIGHT RISK MAY BE NEEDED FOR PORTIONS OF THIS AREA ONCE THESE
UNCERTAINTIES AND CONCERNS HAVE BEEN MITIGATED.
..DIAL.. 05/25/2006
CLICK TO GET WUUS03 PTSDY3 PRODUCT
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 1100Z
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