SPC AC 250100
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0800 PM CDT FRI JUL 24 2009
VALID 250100Z - 251200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MID-UPPER MS VALLEY
WWD INTO A PORTION OF THE CNTRL PLAINS...
...CNTRL PLAINS THROUGH MID-UPPER MS VALLEY AND UPPER GREAT LAKES...
A SWD MOVING COLD FRONT STRETCHES FROM NRN WI SWWD THROUGH CNTRL IA
THEN WWD THROUGH SRN NEB. THE 00Z RAOB DATA INDICATES A RESERVOIR OF
MODERATE INSTABILITY WITH 1500-2500 J/KG MLCAPE IN WARM SECTOR FROM
NEB EWD THROUGH IA...NRN MO AND NWRN IL WHERE PLUME OF STEEPER LAPSE
RATES HAVE OVERSPREAD MOIST AXIS WITH DEWPOINTS IN THE UPPER 60S TO
AROUND 70. STORMS FROM ERN IA THROUGH NRN IL HAVE EVOLVED INTO A
SMALL MCS BUT WITH EMBEDDED ORGANIZED STRUCTURES. INCREASING STORM
RELATIVE INFLOW ASSOCIATED WITH DEVELOPING SWLY LOW LEVEL JET AND
NWLY FLOW ALOFT SHOULD CONTINUE TO PROMOTE SSEWD DEVELOPMENT OF THIS
ACTIVITY WHERE CAP IS WEAKER ALONG INSTABILITY GRADIENT NEXT FEW
HOURS. SOME WWD BACKBUILDING THROUGH SRN IA REMAINS POSSIBLE. NWLY
BULK SHEAR OF 35-45 KT WILL SUPPORT EMBEDDED SUPERCELL AND BOWING
SEGMENTS WITH DAMAGING WIND AND LARGE HAIL THE MAIN THREATS.
HOWEVER...ISOLATED TORNADOES ALSO REMAIN POSSIBLE NEXT COUPLE HOURS.
FARTHER WEST ACROSS NEB...MORE ISOLATED STORMS ARE DEVELOPING ALONG
THE SWD ADVANCING COLD FRONT WHERE CAP IS STRONGER. THE 00Z OMAHA
RAOB SUGGESTS SURFACE BASED CONVECTIVE INHIBITION SHOULD INCREASE
SIGNIFICANTLY AS NOCTURNAL COOLING COMMENCES AND WOULD INDICATE THAT
SURFACE BASED STORMS SHOULD BEGIN TO STRUGGLE AFTER SUNSET.
HOWEVER...OTHER STORMS MAY DEVELOP IN POST FRONTAL ZONE INCLUDING
ACTIVITY SPREADING EWD OUT OF WRN NEB AS THE SWLY LOW LEVEL JET
STRENGTHENS AND INCREASES ISENTROPIC POST FRONTAL LIFT.
SEVERE THREAT WITH STORMS DEVELOPING FARTHER NORTH ALONG COLD FRONT
ACROSS NRN WI WILL PROBABLY REMAIN LIMITED BY THE MARGINAL
THERMODYNAMIC ENVIRONMENT.
...NERN STATES...
LARGE SCALE LIFT ASSOCIATED WITH VORT MAX MOVING THROUGH THE NERN
STATES IS SHIFTING EAST OF MODEST INSTABILITY AXIS. THREAT FOR
ISOLATED HAIL AND DAMAGING WIND MAY PERSIST FOR ANOTHER HOUR OR TWO
WITH ONGOING MULTICELL STORMS...BUT OVERALL TREND SHOULD BE FOR
STORMS TO WEAKEN AS THE BOUNDARY LAYER CONTINUES TO STABILIZE.
...WRN MT...
ISOLATED STORMS WILL CONTINUE DEVELOPING OVER THE HIGHER TERRAIN
NEXT COUPLE HOURS WITHIN ZONE OF DEEPER ASCENT RESULTING FROM NEWD
EJECTING VORT MAX. WHILE BULK SHEAR OF 30-40 KT WILL REMAIN
FAVORABLE FOR SUPERCELL STRUCTURES...MUCH OF THIS REGION HAS BEEN
STABILIZED SOMEWHAT BY PREVIOUS CONVECTION AND ANY REMAINING SEVERE
THREAT SHOULD BE VERY ISOLATED.
..DIAL.. 07/25/2009
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z
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