SWODY1
SPC AC 110533
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1233 AM CDT TUE MAY 11 2010
VALID 111200Z - 121200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN AND
CNTRL PLAINS...OZARKS AND MID-MS VALLEY...
...SRN AND CNTRL PLAINS/OZARKS/MID-MS VALLEY...
AN UPPER-LEVEL LOW OVER THE INTERMOUNTAIN WEST WILL MOVE SLOWLY EWD
AS A WELL-DEFINED 70 TO 80 KT MID-LEVEL JET ROUNDS THE BASE OF THE
ASSOCIATED UPPER-LEVEL TROUGH. AHEAD OF THE SYSTEM...A STRONG
LOW-LEVEL JET WILL TRANSPORT MOISTURE QUICKLY NWD ACROSS WRN OK
WHERE FORECASTS SHOW STRONG INSTABILITY IN PLACE WITH MLCAPE VALUES
IN THE 3000 TO 4000 J/KG BY LATE AFTERNOON. ALTHOUGH LARGE-SCALE
ASCENT IS FORECAST TO BE WEAK ALONG THE DRYLINE...LOW-LEVEL
CONVERGENCE AND A WEAKENING CAPPING INVERSION SHOULD ALLOW
INITIATION OF ISOLATED THUNDERSTORMS LATE THIS AFTERNOON FROM THE
ERN OK AND TX PANHANDLES SWD ACROSS WRN OK INTO NW TX. FORECAST
SOUNDINGS ALONG THIS CORRIDOR AT 00Z SHOW STRONG DEEP LAYER SHEAR
MAINLY NORTH OF I-40 WHERE AN ISOLATED SUPERCELL WITH VERY LARGE
HAIL MAY DEVELOP ALONG THE RETREATING DRYLINE. A VERY CONDITIONAL
SEVERE THREAT WILL ALSO EXIST SWD ACROSS SW OK INTO NW TX WHERE ANY
STORM THAT INITIATES SHOULD HAVE A LARGE HAIL THREAT. WILL NOT
INTRODUCE A SIGNIFICANT HAIL PROBABILITY CONTOUR DUE TO THE ISOLATED
NATURE OF THE THREAT.
FURTHER NORTH AND EAST ACROSS KANSAS AND MISSOURI...MODEL FORECASTS
ARE IN AGREEMENT INITIATING THUNDERSTORMS ALONG THE WARM FRONT THIS
EVENING AS MOISTURE ADVECTION RESULTS IN MODERATE DESTABILIZATION.
FORECAST SOUNDINGS NEAR THE WARM FRONT AT 03Z TO 06Z IN CNTRL KS EWD
INTO WRN MO SHOW ABOUT 50 KT OF 0-6 KM SHEAR WHICH SHOULD SUPPORT
SUPERCELL DEVELOPMENT. THE CURRENT THINKING IS THAT SUPERCELLS WITH
LARGE HAIL WILL DEVELOP ALONG THE WARM FRONT THIS EVENING. THE
STORMS MAY INITIALLY BE SFC-BASED AND HAVE AN ISOLATED TORNADO
THREAT ON THE NOSE OF THE LOW-LEVEL JET. HOWEVER...A NEWD STORM
MOTION SHOULD TAKE THE STORMS NORTH OF THE WARM FRONT OVERNIGHT WITH
CONVECTION BECOMING ELEVATED. THE CONVECTION MAY REMAIN STRONG
ENOUGH FOR A HAIL THREAT AS THE EXIT REGION OF THE MID-LEVEL JET
APPROACHES AFTER MIDNIGHT.
...OH VALLEY...
AN UPPER-LEVEL RIDGE WILL MOVE INTO THE MS VALLEY THIS AFTERNOON AS
AN UPPER-LEVEL TROUGH DE-AMPLIFIES OVER THE GREAT LAKES. A STRONG
LOW-LEVEL JET IS FORECAST TO MOVE EWD ACROSS THE OH VALLEY AS
MOISTURE INCREASES FROM THE SOUTHWEST LATE THIS AFTERNOON. MODEL
FORECASTS DEVELOP A CLUSTER OF THUNDERSTORMS BY 00Z ALONG NRN EDGE
OF INSTABILITY AND MOVE THIS CONVECTION EWD INTO THE CNTRL
APPALACHIAN MTNS. A MARGINAL WIND DAMAGE THREAT COULD ACCOMPANY THE
STORMS DUE TO THE STRONG LOW-LEVEL FLOW EVIDENT ON FORECAST
SOUNDINGS.
...CO FRONT RANGE...
THE EXIT REGION OF A WELL-DEVELOPED MID-LEVEL JET WILL MOVE NEWD
INTO CNTRL CO BY EARLY THIS EVENING AS AN UPPER-LEVEL LOW APPROACHES
FROM THE WEST SOUTHWEST. INCREASING LARGE-SCALE ASCENT AND
TOPOGRAPHIC FORCING SHOULD RESULT IN CONVECTIVE INITIATION ALONG THE
FRONT RANGE AROUND 00Z. ALTHOUGH INSTABILITY IS FORECAST TO BE
WEAK...FORECAST SOUNDINGS SHOW VERY STRONG VERTICAL SHEAR PROFILES
WITH STEEP LAPSE RATES. THIS MAY BE ENOUGH FOR A MARGINAL WIND
DAMAGE THREAT WITH THE STRONGER DOWNDRAFTS.
..BROYLES/STOPPKOTTE.. 05/11/2010
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