Posted by JAC on 5/29/2009, 8:51 am, in reply to "Re: Severe weather returns to the CONUS this weekend"

The shortwave is still forecasted to be negatively tilted. Still have high afternoon CAPE bulls-eyes today, Saturday, and Sunday on the KS/ MO border; with high shear / helicity to the north. SPC still is concerned for Monday. Sunday looks like the worst day. IA, WI, & east MN under the gun. DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0358 AM CDT FRI MAY 29 2009 VALID 011200Z - 061200Z ...DISCUSSION... LATEST MEDIUM-RANGE GUIDANCE IS IN RELATIVELY GOOD AGREEMENT IN THE EVOLUTION OF THE LARGE-SCALE PATTERN THROUGH THE EXTENDED PERIOD. ON D4 /MON JUN 1ST/ ZONAL BELT OF HIGHEST MOMENTUM FLOW WILL EXIST FROM THE N-CNTRL STATES EWD THROUGH THE GREAT LAKES INTO NEW ENGLAND. MODEL DIFFERENCES DO EXIST IN THE LOCATION OF EMBEDDED VORTICITY MAXIMA AND POSITION OF ASSOCIATED SURFACE LOWS...HOWEVER IT APPEARS THAT PRIMARY BAROCLINIC ZONE AT THE SURFACE WILL EXTEND FROM THE SRN GREAT LAKES/OH VALLEY WWD INTO THE CNTRL HIGH PLAINS. THIS BOUNDARY WILL RESIDE ON THE SRN EXTENSION OF THE STRONGER MID AND HIGH-LEVEL WIND FIELDS WHERE THE POTENTIAL WILL EXIST FOR EPISODIC STRONG TO SEVERE STORM DEVELOPMENT ALONG THE LENGTH OF BOUNDARY. BY D5 /TUE JUN 2ND/...IT APPEARS THAT SURFACE BOUNDARY WILL BECOME DISPLACED TO THE S OF THE STRONGER MID AND HIGH-LEVEL WIND FIELDS. WHILE STORMS /SOME SEVERE/ WILL REMAIN POSSIBLE ALONG THIS BOUNDARY...THE POTENTIAL FOR AN ORGANIZED SEVERE WEATHER EPISODE APPEARS SOMEWHAT MARGINAL. THEREAFTER...BROADER TROUGHING IS FORECAST TO DEVELOP OVER THE ERN HALF OF THE NATION WITH TSTMS POSSIBLE ALONG COLD FRONT SLOWLY PUSHING SEWD. UPSTREAM...FLATTENING RIDGE OVER THE ROCKIES WILL SERVE TO ENHANCE LEE CYCLOGENESIS/TROUGHING OVER THE NRN AND CNTRL HIGH PLAINS TOWARD THE END OF THE PERIOD...AND SOME SEVERE WEATHER IS POSSIBLE. GIVEN UNCERTAINTIES IN MORE EXACT FRONTAL POSITIONS AND DEGREE OF AIR MASS STABILITY...NO ADDITIONAL SEVERE WEATHER AREAS WILL BE INCLUDED IN THIS FORECAST. ..MEAD.. 05/29/2009