SPC AC 211644
DAY 1 CONVECTIVE OUTLOOK CORR 1
NWS STORM PREDICTION CENTER NORMAN OK
1144 AM CDT SUN JUN 21 2009
VALID 211630Z - 221200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF IA/IL/SRN
MN/SWRN WI/NRN MO...
...THERE IS A SLGT RISK OF SVR TSTMS OVER THE NRN INTERMOUNTAIN
REGION...
CORRECTED GRAPHIC
...IA/IL/NRN MO/SRN MN/SWRN WI...
WEAKENING MOIST CONVECTION IS EXPECTED TO CONTINUE LIFTING NNEWD
ACROSS THE UPPER MS RIVER VALLEY TODAY ASSOCIATED WITH EJECTING
SHORTWAVE TROUGH. IN THE WAKE OF THIS ACTIVITY...SURFACE WARM FRONT
WILL REMAIN WELL DEFINED FROM PORTIONS OF CENTRAL IL INTO
CENTRAL/NRN IA AND SHOULD PROVIDE FOCUS FOR INCREASING SEVERE THREAT
LATER TODAY. STRONG HEATING ALONG THE MO RIVER VALLEY SHOULD ALLOW
AXIS OF NEAR 90F SURFACE TEMPERATURES TO NOSE INTO NWRN IA WHERE
CONVECTIVE INHIBITION WILL BECOME QUITE WEAK BY 21Z...ALTHOUGH WEAK
LAPSE RATES ARE EXPECTED TO LIMIT AVAILABLE MLCAPE. REGARDLESS...
AIRMASS WILL STILL BECOME MODERATELY UNSTABLE AND SEVERE
THUNDERSTORM DEVELOPMENT IS EXPECTED NEAR THE WARM FRONT OVER NWRN
IA DURING THE LATE AFTERNOON. ACTIVITY WILL LIKELY INCREASE IN
COVERAGE AND INTENSITY ESEWD THROUGH THE EVENING. MODERATE TO
STRONG SWLY H85 FLOW WILL SUPPORT FAIRLY LARGE LOW LEVEL HODOGRAPHS
NEAR THE SURFACE WARM FRONT WITHIN DEEP LAYER SHEAR AROUND 35
KT...BOTH SUPPORTIVE OF A RISK OF TORNADIC SUPERCELLS AND SMALL
SCALE BOW ECHOES INTO THE EARLY TO MID EVENING.
...NRN INTERMOUNTAIN REGION INTO THE NRN/CENTRAL HIGH PLAINS...
COOL CYCLONIC FLOW WILL PREVAIL OVER THE NRN INTERMOUNTAIN REGION
TODAY...DOWNSTREAM FROM CONSOLIDATING TROUGH IN ORE/NV. MODEST
DESTABILIZATION AHEAD OF TROUGH SHOULD LEAD TO AFTERNOON STORM
DEVELOPMENT FROM NE NV/NRN UT NEWD INTO PARTS OF ID/WRN MT AND WRN
WY. 30-40 KT DEEP SSWLY SHEAR WILL FOSTER ORGANIZATION OF
CONVECTION INTO ONE OR MORE BANDS/CLUSTERS. EMBEDDED STRONGER/
SUSTAINED STORMS COULD YIELD ISOLATED DAMAGING WINDS AND LARGE HAIL
THROUGH THE EARLY EVENING.
FARTHER EAST OVER THE HIGH PLAINS...SUFFICIENT VERTICAL MOTION AND
MODEST INSTABILITY SHOULD SUPPORT CLUSTERS OF STRONG TO ISOLATED
SEVERE STORMS INVOF LEE TROUGH OVER WRN ND AND INTO SERN WY/NERN CO.
HOWEVER...OVERALL THREAT APPEARS TOO ISOLATED TO WARRANT GREATER
SEVERE PROBABILITIES ATTM.
...MID/UPPER MS RIVER VALLEY INTO SRN APPALACHIANS/SC-GA COAST...
PERSISTENT SE-NW ORIENTED SURFACE FRONT TOPPED BY MODEST NWLY
MID/UPPER LEVEL FLOW WILL MAINTAIN A THREAT OF ISOLATED SEVERE
ACROSS THIS CORRIDOR THIS AFTERNOON. LITTLE OR NO LARGE SCALE
SUPPORT IS EVIDENT ON WV IMAGERY THIS MORNING. HOWEVER AS CAP
WEAKENS AND ISOLATED STORMS DEVELOP VIA AFTERNOON HEATING...DEEP
LAYER SHEAR WILL BE SUPPORTIVE OF ORGANIZATION AND POSSIBILITY OF
ISOLATED WIND DAMAGE. ALTHOUGH WEAK LAPSE RATES AND LACK OF FOCUSED
ASCENT WILL TEND TO HINDER OVERALL SEVERE THREAT ACROSS THE BROADER
AREA.
..SELECT A FORECASTER.. 06/21/2009
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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