SWODY1
SPC AC 140100
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0800 PM CDT MON AUG 13 2007
VALID 140100Z - 141200Z
..THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF SRN MN...WRN WI
AND NE IA...
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NRN
PLAINS...UPPER MIDWEST AND LOWER OH VALLEY...
A BROAD UPPER-LEVEL RIDGE IS EVIDENT ON WATER VAPOR IMAGERY OVER THE
PLAINS STATES WITH SEVERAL LOW-AMPLITUDE SHORTWAVE TROUGHS EMBEDDED
IN THE TOP OF THE RIDGE OVER THE NRN PLAINS AND SRN MANITOBA. RUC
ANALYSIS SUGGESTS THE LEADING EDGE OF LARGE-SCALE ASCENT IS LOCATED
FROM CNTRL MN EXTENDING SWWD INTO NERN SD. THE STRONGER LIFT SHOULD
SPREAD EWD...INCREASING ASCENT ACROSS SRN AND ERN MN WITH STORM
COVERAGE EXPANDING ACROSS THE MODERATE RISK AREA. MODEL FORECASTS
ARE CONSISTENT WITH DEVELOPING A VERY ORGANIZED CONVECTIVE CLUSTER
MOVING THE MCS SEWD FROM SCNTRL MN INTO NE IA AND SW WI DURING THE
OVERNIGHT PERIOD.
OBJECTIVE ANALYSIS ACROSS THE REGION INDICATES MLCAPE VALUES
CURRENTLY RANGE FROM 4000 TO 5000 J/KG WITH SFC DEWPOINTS IN THE
LOWER TO MID 70S F. A PLUME OF VERY STEEP LAPSE RATES ALSO EXISTS
FROM SERN SD EXTENDING NEWD ACROSS SRN MN. IN ADDITION...SELY SFC
WINDS AND 50 KT OF WLY FLOW AT MID-LEVELS SHOWN ON THE WOOD LAKE MN
PROFILER IS CREATING STRONG VERTICAL SHEAR OF 50 TO 60 KT. THE
COMBINATION OF INSTABILITY...SHEAR AND STEEP LAPSE RATES WILL BE
VERY FAVORABLE FOR SUPERCELLS WITH LARGE HAIL ESPECIALLY AS AN MCS
ORGANIZES THIS EVENING. REGIONAL PROFILERS ALSO SHOW LARGE
HODOGRAPHS WHICH WILL BE SUFFICIENT FOR TORNADOES WITH THE BETTER
ORGANIZED SUPERCELLS. THE GREATEST TORNADO POTENTIAL SHOULD EXIST IN
THE MIDDLE TO LATE EVENING ALONG THE I-94 CORRIDOR FROM ALEXANDRIA
MN SEWD TO MINNEAPOLIS/ST PAUL SWD TO THE IA STATE LINE. AN MCS
SHOULD GRADUALLY ORGANIZE ALONG THIS CORRIDOR AND THE WIND DAMAGE
POTENTIAL SHOULD INCREASE THROUGH LATE EVENING. SIGNIFICANT WIND
DAMAGE WILL BE POSSIBLE AS A LARGE-SCALE BOW DEVELOPS AND MOVES INTO
NE IA AND WRN WI JUST AFTER MIDNIGHT.
THE SEVERE THREAT SHOULD CONTINUE WITH THE MCS AFTER MIDNIGHT WITH
WIND DAMAGE AND HAIL AS THE PRIMARY THREATS. THE SEVERE THREAT
SHOULD GRADUALLY DECREASE IN COVERAGE AS INSTABILITY WEAKENS ACROSS
THE REGION LATE TONIGHT.
.BROYLES.. 08/14/2007
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