SWODY1
SPC AC 091628
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1128 AM CDT TUE JUN 09 2009
VALID 091630Z - 101200Z
...THERE IS A MDT RISK OF SVR TSTMS ACROSS S CENTRAL/SE KS INTO
EXTREME NRN OK AND SW MO THROUGH LATE EVENING...
...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK
AREA...FROM NE CO AND NW TX EWD TO THE OH
VALLEY...APPALACHIANS...AND S CENTRAL NY...
...CENTRAL/SRN PLAINS AREA THROUGH TONIGHT...
AN ONGOING CLUSTER OF SLIGHTLY ELEVATED THUNDERSTORMS APPEARS TO BE
IN THE PROCESS OF EVOLVING INTO A FORWARD-PROPAGATING MCS FROM ERN
KS INTO WRN MO. GIVEN A FEED OF STRONG INSTABILITY FROM THE SW AND
LOW-LEVEL DESTABILIZATION ASSOCIATED WITH DAYTIME HEATING AND NWD
PROGRESS OF THE WARM FRONT FROM OK/AR INTO SE KS/SW MO...THIS
CONVECTION WILL LIKELY BECOME ROOTED NEAR THE GROUND WITH AN
INCREASING WIND DAMAGE THREAT THROUGH THE AFTERNOON AS THE COLD POOL
STRENGTHENS. OUTFLOW FROM THIS CONVECTION IS ALSO MOVING SWD ACROSS
CENTRAL KS AND WILL CROSS SE KS EARLY THIS AFTERNOON...AS THE WARM
FRONT LIFTS NWD. THE NET RESULT SHOULD BE CONSOLIDATION OF A
PRONOUNCED BAROCLINIC ZONE FROM SW MO ENEWD INTO SE KS...AND THEN
WWD INTO S CENTRAL KS.
ADDITIONAL SURFACE-BASED THUNDERSTORMS WILL LIKELY FORM AROUND MID
AFTERNOON ALONG THE OUTFLOW BOUNDARY AND NEAR THE TRIPLE POINT WITH
THE DRYLINE ACROSS SRN KS AND PERHAPS EXTREME NRN OK. CONTINUED
DAYTIME HEATING /TEMPERATURES WARMING TO THE UPPER 80S TO LOWER 90S/
AND BOUNDARY LAYER DEWPOINTS OF 68-70 F...BENEATH STEEP MID LEVEL
LAPSE RATES...WILL CONTRIBUTE TO STRONG INSTABILITY /MLCAPE VALUES
AOA 3000 J/KG/ AND WEAKENING CONVECTIVE INHIBITION.
MEANWHILE...DEEP LAYER VERTICAL SHEAR WILL REMAIN FAVORABLE FOR
SUPERCELLS...AS SOME INCREASE IN MID LEVEL FLOW SHOULD OCCUR IN
CONJUNCTION WITH A SUBTLE SPEED MAX EJECTING NEWD FROM NM IN ADVANCE
OF THE PRIMARY MID LEVEL TROUGH OVER THE SWRN STATES. FORECAST
SOUNDINGS E OF THE TRIPLE POINT AND NEAR THE OUTFLOW/WARM FRONT SHOW
FAVORABLE PROFILES FOR SUPERCELLS CAPABLE OF PRODUCING VERY LARGE
HAIL...DAMAGING WINDS...AND ISOLATED STRONG TORNADOES. THE
AFTERNOON CONVECTION MAY GROW INTO ANOTHER MCS OVERNIGHT AND SPREAD
EWD ACROSS MO IN ASSOCIATION WITH AN INCREASE IN THE LLJ AND WAA
OVER THE REMNANT COLD POOL FROM THE ONGOING ACTIVITY IN KS/MO.
FARTHER S...AS DURING PREVIOUS DAYS...STRONG SURFACE HEATING COULD
SUPPORT ISOLATED THUNDERSTORM DEVELOPMENT ALONG THE DRYLINE IN TX.
IF STORMS FORM...ISOLATED LARGE HAIL AND DAMAGING WINDS CAN BE
EXPECTED.
...OH VALLEY/APPALACHIANS AREA TO CENTRAL NY THIS AFTERNOON...
COMPLICATED FORECAST TODAY WITH SEVERAL SMALL SCALE SPEED MAXIMA
PROGRESSING EWD FROM THE OH VALLEY TO THE APPALACHIANS...S OF THE
MAIN BELT OF WLYS AND THE PRIMARY SHORTWAVE TROUGH NEAR AND N OF THE
SAINT LAWRENCE VALLEY. AT THE SURFACE...A COLD FRONT IS MOVING
SLOWLY EWD INTO WRN NY/PA AND SEWD TOWARD THE OH RIVER...WHILE A
WARM FRONT IS LIFTING SLOWLY NEWD ACROSS ERN PA AND SRN/SERN NY.
REGIONAL 12Z SOUNDINGS REVEAL RELATIVELY STEEP MID LEVEL LAPSE RATES
AND POTENTIALLY MODERATE INSTABILITY /MLCAPE VALUES OF 1500-2500
J/KG/ ONCE AFTERNOON TEMPERATURES WARM INTO THE UPPER 70S ACROSS NY
...THE LOW-MID 80S TOWARD THE OH VALLEY...AND THE UPPER 80S IN THE
LEE OF THE CENTRAL/SRN APPALACHIANS. THERE WILL BE THE POTENTIAL
FOR SCATTERED THUNDERSTORM DEVELOPMENT THIS AFTERNOON ALONG THE
SURFACE FRONT AND IN ADVANCE OF THE SUBTLE MID LEVEL SPEED MAXIMA
FROM THE OH VALLEY NEWD INTO PA/NY. THE STRONGER LOW-MID LEVEL FLOW
AND VERTICAL SHEAR WILL RESIDE OVER PA AND ESPECIALLY NY...WHERE
ORGANIZED CLUSTERS/LINE SEGMENTS COULD PRODUCE DAMAGING WINDS AND
LARGE HAIL. FARTHER S AND SW TOWARD THE OH VALLEY AND
APPALACHIANS...DIURNAL PULSE-TYPE CONVECTION WILL BE CAPABLE OF
PRODUCING DAMAGING DOWNBURST WINDS AND LARGE HAIL IN THE RELATIVELY
WEAK VERTICAL SHEAR ENVIRONMENT.
...SE FL COAST THIS AFTERNOON...
WITH WEAK MEAN NWLY FLOW IN THE LOW-MID LEVELS...THE SE FL SEA
BREEZE SHOULD REMAIN ANCHORED CLOSE TO THE COAST THIS AFTERNOON.
THE THERMODYNAMIC ENVIRONMENT WILL AGAIN BE SUPPORTIVE OF ISOLATED
DAMAGING WET MICROBURSTS AND MARGINALLY SEVERE HAIL.
..THOMPSON/GARNER.. 06/09/2009
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