SWODY1
SPC AC 150053
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0753 PM CDT TUE AUG 14 2007
VALID 150100Z - 151200Z
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL
PLAINS...NRN PLAINS AND UPPER MIDWEST...
..CNTRL AND NRN PLAINS/UPPER MIDWEST...
WATER VAPOR IMAGERY SHOWS A BROAD UPPER-LEVEL RIDGE IN PLACE ACROSS
THE CNTRL PLAINS. AT THE SFC...A QUASI-STATIONARY FRONT IS LOCATED
FROM SRN NEB EXTENDING EWD ACROSS NRN MO. NORTH OF THE
BOUNDARY...DEWPOINTS ARE IN THE LOWER TO MID 70S F AND OBJECTIVE
ANALYSIS SHOWS STRONG INSTABILITY IN PLACE WITH MLCAPE VALUES IN THE
4000 TO 5000 J/KG. ALTHOUGH LARGE-SCALE ASCENT IS WEAK DUE TO THE
UPPER-LEVEL RIDGE...THE STRONG INSTABILITY WILL CONTINUE TO SUPPORT
SCATTERED THUNDERSTORM DEVELOPMENT. IN ADDITION...A LOW-LEVEL JET
WILL GRADUALLY INCREASE THIS EVENING AND MCS DEVELOPMENT WILL BE
POSSIBLE ON THE NOSE OF THE LOW-LEVEL JET ACROSS SERN SD...FAR SRN
MN AND NRN IA DURING THE OVERNIGHT PERIOD.
CONCERNING THE SHEAR ENVIRONMENT...THE NERN NEB PROFILER SHOWS
SUBSTANTIAL VEERING BELOW 2 KM WITH ABOUT 30 KT OF WLY FLOW AT
MID-LEVELS. THIS APPEARS REPRESENTATIVE ACROSS MOST OF THE SLIGHT
RISK AREA SUGGESTING ENOUGH SHEAR IS IN PLACE FOR SUPERCELLS.
HOWEVER...AS INSTABILITY DECREASES THIS EVENING AND A CAPPING
INVERSION BECOMES REESTABLISHED...THE SUPERCELL POTENTIAL SHOULD
DECREASE WITH TIME. THE GREATEST POTENTIAL FOR SEVERE STORM
DEVELOPMENT SHOULD BE AS THE LOW-LEVEL JET INCREASES LATE THIS
EVENING. SEVERE STORMS CAPABLE OF LARGE HAIL AND ISOLATED WIND
DAMAGE WILL BE POSSIBLE MAINLY DUE TO THE STRONG INSTABILITY ACROSS
NRN NEB AND IA. MODEL FORECASTS ARE CONSISTENT DEVELOPING AN MCS
LATE TONIGHT ALONG THE CORRIDOR FROM SIOUX FALLS SD TO DES MOINES
IA. HOWEVER...THE THUNDERSTORMS ASSOCIATED WITH THIS MCS MAY REMAIN
ELEVATED WITH ONLY A MARGINAL SEVERE THREAT MAINLY DUE TO THE TIME
OF DAY.
.BROYLES.. 08/15/2007
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