SPC AC 150544
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1244 AM CDT WED JUL 15 2009
VALID 151200Z - 161200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE OH
VALLEY...OZARKS AND CNTRL PLAINS...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF ERN CO...NE
NM...THE WRN OK PANHANDLE AND FAR NW TX PANHANDLE...
...OH VALLEY/SRN GREAT LAKES...
AN UPPER-LEVEL TROUGH OVER THE UPPER MS VALLEY WILL MOVE EWD AND
BROADEN TODAY. AN MCS SHOULD BE ONGOING ACROSS THE WRN PART OF THE
OH VALLEY THIS MORNING. BEHIND THE CLUSTER OF STORMS...A COLD FRONT
WILL MOVE SEWD REACHING NRN IL AND SERN WI THIS AFTERNOON. AN AXIS
OF MODERATE INSTABILITY IS FORECAST JUST AHEAD OF THE FRONT FROM
CNTRL MO EXTENDING NEWD ACROSS CNTRL IL INTO NRN IND AND LOWER MI.
THE EXIT REGION OF A BROAD MID-LEVEL JET WILL OVERSPREAD THE
INSTABILITY AXIS LATE THIS AFTERNOON HELPING TO CREATE MODERATE
VERTICAL SHEAR PROFILES FAVORABLE FOR SEVERE STORMS. THE MODEL
SOLUTIONS ARE QUITE VARIED ACROSS THE OH VALLEY AND HOW MUCH
CONVECTION WILL DEVELOP ALONG THE FRONTAL BOUNDARY REMAINS
QUESTIONABLE. THE CURRENT THINKING IS THAT THE NAM IS UNDERDONE WITH
CONVECTIVE COVERAGE AND THAT THE SCENARIO WILL PAN OUT MORE LIKE THE
GFS SOLUTION. THIS WOULD RESULT IN A CONVECTIVE COMPLEX DEVELOPING
IN IL AND IND THIS AFTERNOON WITH THIS CLUSTER MOVING INTO THE UPPER
OH VALLEY BY EARLY EVENING. VEERED LOW-LEVEL WIND PROFILES...STEEP
LOW-LEVEL LAPSE RATES AND ABOUT 25 KT OF FLOW AROUND 850 MB SHOULD
BE FAVORABLE FOR WIND DAMAGE ESPECIALLY IF A COLD POOL CAN ORGANIZE.
HAIL WILL ALSO BE POSSIBLE WITH THE STRONGER CORES.
...ERN CO/NE NM/WRN NEB...
THUNDERSTORMS WILL AGAIN DEVELOP IN WEST NORTHWEST FLOW ALOFT IN THE
HIGHER TERRAIN OF ECNTRL CO AND NERN NM TODAY. THE CONVECTION SHOULD
MOVE SLOWLY EWD ACROSS THE SERN CO AND NERN NM PLAINS THIS
AFTERNOON. FORECAST SOUNDINGS IN SE CO AT 21Z SHOW 40-50 KT OF
VERTICAL SHEAR LARGELY DUE TO DIRECTIONAL SHEAR AND STRONG MID-LEVEL
FLOW. IN ADDITION...ELY SFC WINDS SHOULD BRING SFC DEWPOINTS IN SERN
CO INTO THE 50S F RESULTING IN MODERATE DESTABILIZATION. THE
INSTABILITY AND VERTICAL SHEAR COMBINED WITH VERY STEEP LAPSE RATES
SHOULD BE FAVORABLE FOR HAIL. ISOLATED WIND DAMAGE WILL ALSO BE
POSSIBLE ESPECIALLY IF A LINE-SEGMENT CAN ORGANIZE DURING THE LATE
AFTERNOON. MODEL FORECASTS DESTABILIZE THE MOIST AXIS NWD ACROSS NE
CO AND WRN NEB SUGGESTING ISOLATED MARGINALLY SEVERE STORMS WILL
ALSO BE POSSIBLE FURTHER NORTH.
...CNTRL AND SRN PLAINS/NRN OZARKS...
WEST TO NORTHWEST FLOW WILL BE IN PLACE TODAY AS A COLD FRONT MOVES
SWD INTO THE CNTRL PLAINS TODAY. AN AXIS OF MODERATE INSTABILITY IS
FORECAST SOUTH OF THE BOUNDARY EXTENDING EWD ACROSS SRN KS INTO
CNTRL MO. MODEL SOLUTIONS ARE NOT IN AGREEMENT THIS AFTERNOON
CONCERNING CONVECTIVE INITIATION. THE CURRENT THINKING IS THAT STORM
DEVELOPMENT WILL HOLD OFF UNTIL EVENING DUE TO A STRONG CAPPING
INVERSION. THEN AS THE LOW-LEVEL JET INCREASES...SEVERAL CLUSTERS
SHOULD DEVELOP BY MID TO LATE EVENING MOVING EWD ACROSS THE SEE TEXT
AREA DURING THE OVERNIGHT PERIOD. FORECAST SOUNDINGS ACROSS SRN KS
AND SCNTRL MO BY LATE EVENING SHOW ENOUGH VERTICAL SHEAR AND
INSTABILITY FOR AN ISOLATED HAIL AND WIND DAMAGE THREAT.
..BROYLES/JEWELL.. 07/15/2009
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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