DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 280743
SWODY3
SPC AC 280742

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0242 AM CDT SAT APR 28 2007

VALID 301200Z - 011200Z

..THERE IS A SLGT RISK OF SVR TSTMS PARTS OF THE MIDWEST/UPPER
GREAT LAKES....

..SYNOPSIS...
MID/UPPER LEVEL TROUGH IS FORECAST TO MOVE SEWD FROM SASKATCHEWAN
INTO THE UPPER GREAT LAKES DURING THE PERIOD. THIS WILL ENHANCE
NWLY FLOW REGIME ACROSS THE UPPER MIDWEST INTO THE GREAT LAKES
REGION AND BRING THE NEXT COLD FRONT SEWD INTO NEB/IA AND NRN IL BY
01/1200Z.

..PARTS OF SRN MN/IA INTO WI AND NRN IL...

LOW PRESSURE IS EXPECTED TO MOVE FROM SERN SD EWD INTO SERN LOWER MI
DURING THE PERIOD AHEAD OF SELY MOVING MID LEVEL SHORTWAVE TROUGH.
LOW LEVEL JET OF 40-45 KT IS PROGGED FROM NERN KS INTO E CENTRAL IA
ENHANCING LOW LEVEL WARM ADVECTION ACROSS THE REGION BY EVENING.
MEANWHILE...WNWLY JET OF 80-100 KT AT 300 MB WILL EXTEND FROM NRN MN
EWD ACROSS THE NRN GREAT LAKES REGION PLACING AREA IN FAVORABLE
ENTRANCE REGION ENHANCING UVVS AHEAD OF SURFACE LOW MOVING THROUGH
THE AREA. THIS WILL BRING DEEP LAYER SHEAR PROFILE OF 45-55 KT TO
THE REGION SUFFICIENT TO SUSTAIN STRONG UPDRAFTS IN CONVECTIVE
ACTIVITY DEVELOPING IN WARM ADVECTION REGIME. NAM GENERATES
2000-3000 J/KG OF MUCAPE WITH ADDITION OF AFTERNOON HEATING AS GFS
CORRELATES IT WITH LIFTED INDICES OF -6.

THUS...WOULD EXPECT SEVERE THUNDERSTORMS TO DEVELOP ALONG/JUST NORTH
OF WARM FRONTAL BOUNDARY EXTENDING FROM CENTRAL IA SEWD INTO SWRN OH
BY LATE IN THE AFTERNOON. GIVEN THAT THERE WILL BE FAVORABLE
VERTICAL SHEAR ENHANCED BY W-NW FLOW WITH STORM RELATIVE HELICITY
ESTIMATES OF 300-400 M2/S2 WOULD INDICATE A FAVORABLE SETTING FOR
SUPERCELLS NEAR THE BOUNDARY.

..PARTS OF THE SOUTHERN PLAINS...

SOUTHERN STREAM MID/UPPER LEVEL LOW WILL CONTINUE EWD ACROSS WRN
INTO CENTRAL TX DURING THE PERIOD. WIDELY SCATTERED THUNDERSTORMS
ARE EXPECTED TO CONTINUE WITH THIS FEATURE. MODELS INDICATE
POTENTIAL INSTABILITY TO AROUND 1000 J/KG TO SUPPORT A THREAT FOR
STRONG WINDS AND HAIL.

.MCCARTHY.. 04/28/2007

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