SWODY1
SPC AC 030559
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CDT TUE JUN 03 2008
VALID 031200Z - 041200Z
...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON THROUGH TONIGHT
ACROSS PARTS OF ERN MO...CENTRAL AND SRN IL...IND AND OH...
...THERE IS A SLGT RISK OF SVR TSTMS EXTENDING FROM THE CENTRAL HIGH
PLAINS EWD THROUGH THE LOWER MO VALLEY TO PA...
...SYNOPSIS...
A TROUGH IS EXPECTED TO EVOLVE OVER THE WRN STATES TODAY AS A COUPLE
OF PACIFIC TROUGHS AND ACCOMPANYING STRONG MID/UPPER LEVEL WNWLY
FLOW DIG SEWD INTO THE INTERMOUNTAIN WEST. BAND OF STRONG FLOW
ALOFT IS EXPECTED TO EXTEND FROM THE CENTRAL ROCKIES THROUGH THE MID
MS/OH VALLEYS AND NERN STATES...WITH SEVERAL EMBEDDED SHORT WAVE
TROUGHS/IMPULSES TRANSLATING ENEWD IN THIS FLOW FIELD. A MORE
DEFINED SHORT WAVE TROUGH...CURRENTLY MOVING ACROSS THE LOWER CO
RIVER VALLEY PER WATER VAPOR IMAGERY...IS EXPECTED TO REACH THE SRN
HIGH PLAINS TO ERN CO BY LATE THIS AFTERNOON. THIS FEATURE WILL
THEN MOVE INTO KS/OK TONIGHT. MEANWHILE...A SHORT WAVE TROUGH...
INITIALLY LOCATED OVER SRN QUEBEC WILL TRACK EWD TODAY.
IN THE LOW LEVELS...A COLD FRONT ATTENDANT TO THE QUEBEC TROUGH WILL
MOVE SEWD ACROSS THE NERN STATES WITH THE WRN EXTENT SETTLING SWD
AND STALLING IN THE OH VALLEY. FARTHER W...A SURFACE LOW LOCATED
OVER CENTRAL KS AT 12Z TODAY WILL TRACK ENEWD ALONG A BAROCLINIC
ZONE EXTENDING ENEWD ACROSS MO INTO THE LOWER OH VALLEY.
...MID MS/OH VALLEYS...
TSTMS SHOULD BE ONGOING ACROSS THE LOWER OH VALLEY AT 12Z TODAY.
STRENGTHENING SWLY LOW LEVEL WINDS FROM THE MID MS INTO THE OH
VALLEY WILL ADVECT MOISTURE NEWD TODAY...WITH SURFACE HEATING/
DESTABILIZATION DOWNSTREAM OF MORNING ACTIVITY SUPPORTING ADDITIONAL
TSTM DEVELOPMENT EWD INTO OH/KY THIS MORNING INTO THE AFTERNOON.
STRENGTHENING WLY MID LEVEL WINDS ATOP THE SWLY LLJ WILL RESULT IN
SUFFICIENT EFFECTIVE BULK SHEAR FOR STRONG TO SEVERE STORMS WITH
THIS ACTIVITY.
A GREATER SEVERE STORM POTENTIAL IS EXPECTED ACROSS THE OH VALLEY
DEVELOPING THIS AFTERNOON OVER IL/IND AND SPREADING EWD THROUGH THE
REST OF THE OH VALLEY THIS EVENING/TONIGHT. SURFACE HEATING IS
EXPECTED IN THE WAKE OF THE MORNING CONVECTION ACROSS THE LOWER OH
VALLEY... MAINLY ALONG AND S OF THE SURFACE FRONT. THIS COMBINED
WITH INCREASING MOISTURE /SURFACE DEWPOINTS TO AROUND 70/ BENEATH
PLUME OF STEEP MID LEVEL LAPSE RATES EXTENDING EWD OVER THIS AREA
WILL RESULT IN MODERATE TO STRONG INSTABILITY /MLCAPE 2000-2500
J/KG/ BY AFTERNOON. 50-70 KT WLY MID LEVEL FLOW SPREADING INTO THE
MID MS/LOWER OH VALLEYS BY MID-LATE AFTERNOON COMBINED WITH 30-40 KT
SWLY LLJ INTO THIS REGION WILL RESULT IN 40-50 KT OF EFFECTIVE BULK
SHEAR. THE FAVORABLE KINEMATICS AND THERMODYNAMICS WILL SUPPORT
SUPERCELLS WITH THE TSTMS THAT DEVELOP ALONG THE FRONT FROM NRN MO
INTO CENTRAL IL TO CENTRAL/SRN IND IN THE AFTERNOON. GIVEN
LIKELIHOOD FOR BACKED SURFACE WINDS IN VICINITY OF BAROCLINIC
ZONE...AND WINDS VEERING WITH HEIGHT... LARGE HODOGRAPHS WILL
PROMOTE THREAT FOR TORNADOES...SOME STRONG. MODELS TEND TO AGREE
THAT A FORWARD PROPAGATING MCS WILL BE POSSIBLE THIS
EVENING/TONIGHT...WITH THREAT FOR DAMAGING WINDS BECOMING THE
PRIMARY THREAT EWD THROUGH THE MID-UPPER OH VALLEY AFTER DARK.
ISOLATED TORNADOES WILL REMAIN A THREAT GIVEN FURTHER STRENGTHENING
OF LLJ ACROSS OH TO WRN PA/CENTRAL APPALACHIANS TONIGHT...ENHANCING
LOW LEVEL SHEAR. THREAT FOR STRONG WINDS MAY DEVELOP EWD LATE
TONIGHT ACROSS SRN PA/NRN MD.
...PLAINS STATES...
A COUPLE OF SURFACE BOUNDARIES MOVING SWD ACROSS NEB AND KS ARE
EXPECTED TO BE THE FOCI FOR TSTM DEVELOPMENT TODAY...GIVEN A
RESIDUAL MOIST BOUNDARY LAYER..SURFACE HEATING AND STEEP LAPSE RATES
CONTRIBUTE TO STRONG INSTABILITY. MODELS SUGGEST THE POTENTIAL FOR
NEW TSTM DEVELOPMENT MAY OCCUR EARLIER ACROSS NEB WHERE THE CAP
SHOULD BE WEAKER. FARTHER S ACROSS SRN KS...TSTM DEVELOPMENT MAY
REQUIRE FORCING FOR ASCENT WITH THE LOWER CO RIVER VALLEY TROUGH
APPROACHING THIS REGION AND WEAKENING THE STRONGER CAP. ADDITIONAL
TSTM DEVELOPMENT WILL BE POSSIBLE IN POST-FRONTAL UPSLOPE FLOW INTO
THE HIGHER TERRAIN OF CO/WY. ALL OF THESE AREAS WILL HAVE THE
POTENTIAL FOR ORGANIZED SEVERE STORMS...SINCE THIS REGION WILL
RESIDE BENEATH STRONG FLOW ALOFT RESULTING IN EFFECTIVE BULK SHEAR
AROUND 50 KT WITHIN A MODERATELY UNSTABLE AIR MASS.
UPSCALE DEVELOPMENT INTO A COUPLE OF TSTM CLUSTERS/MCSS PRODUCING
STRONG TO SEVERE STORMS APPEARS POSSIBLE TONIGHT. THE FIRST AREA
SHOULD BE ACROSS THE CENTRAL HIGH PLAINS AS A SELY LLJ STRENGTHENS
INTO THIS REGION BENEATH PLUME OF STEEP MID LEVEL LAPSE RATES. THE
SECOND AREA SHOULD BE ACROSS SRN KS/NRN OK INTO SWRN MO AS ASCENT
WITH THE SRN STREAM TROUGH AND INCREASING WAA ALONG A STRENGTHENING
SRN PLAINS LLJ DEVELOP OVER THIS AREA.
...UPPER TN VALLEY/SRN APPALACHIANS TO SERN STATES...
MODELS SUGGEST CONVECTION WILL BE LIKELY ACROSS THIS REGION TODAY.
25-40 KT OF NWLY FLOW EXTENDING SEWD INTO WRN CAROLINAS/NRN GA WILL
PROVIDE SUFFICIENT DEEP LAYER SHEAR FOR SOME STORM ORGANIZATION
WITHIN A MODERATELY UNSTABLE AIR MASS. HAIL AND DAMAGING WINDS
SHOULD BE THE PRIMARY THREATS WITH THIS ACTIVITY.
..PETERS/JEWELL.. 06/03/2008
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