Categorical Graphic
Probabilistic Tornado Graphic
Probabilistic Damaging Wind Graphic
Probabilistic Large Hail Graphic

   SPC AC 091959
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0259 PM CDT TUE JUN 09 2009
   
   VALID 092000Z - 101200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS SOUTH CENTRAL AND
   SOUTHEAST KANSAS...NORTH CENTRAL AND NORTHEAST OKLAHOMA...AND PARTS
   OF SOUTHWEST MISSOURI...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CENTRAL HIGH
   PLAINS...ACROSS KS AND PORTIONS OF THE SRN PLAINS...AND ACROSS THE
   OH AND TN VALLEYS INTO THE ATLANTIC COAST STATES/NY/PA...
   
   ...CENTRAL AND SRN PLAINS REGION...
   A CLUSTER OF VIGOROUS STORMS CONTINUES MOVING ESEWD ACROSS ERN KS
   AND MO ATTM...WITH THE STRONGEST/SUPERCELL-TYPE STORMS ALONG THE SRN
   FRINGE OF THIS ACTIVITY FROM SERN KS INTO THE SRN HALF OF MO INVOF
   THE OUTFLOW-ENHANCED WARM FRONT EXTENDING ROUGHLY W-E ACROSS THIS
   REGION.
   
   A MOIST BOUNDARY LAYER /DEWPOINTS IN THE UPPER 60S TO NEAR 70/
   BENEATH VERY STEEP MID-LEVEL LAPSE RATES COMBINED WITH AFTERNOON
   HEATING HAS YIELDED A VERY UNSTABLE AIRMASS NEAR AND S OF THE
   SURFACE BOUNDARY...WITH OBJECTIVE ANALYSES REVEALING MIXED-LAYER
   CAPE LOCALLY IN EXCESS OF 3000 J/KG CONFIRMED BY AFTERNOON NORMAN OK
   AND SPRINGFIELD MO RAOBS.
   
   LATEST VIS IMAGERY INDICATES A DEVELOPING CU FIELD ALONG THE SURFACE
   BOUNDARY EXTENDING WWD FROM THE ONGOING SUPERCELL STORMS OVER SERN
   KS.  GIVEN THE DEGREE OF INSTABILITY AND RAOB/PROFILER DATA
   DEPICTING DEEP-LAYER SHEAR FAVORABLE FOR SUPERCELLS...THREAT FOR
   ISOLATED/STRONG TORNADOES WILL CONTINUE...ALONG WITH VERY LARGE
   HAIL.  IN ADDITION...STORMS NOW ONGOING ACROSS MO SHOULD SLOWLY
   EVOLVE INTO A LARGE MCS...WITH INCREASING THREAT FOR DAMAGING WINDS
   INTO THIS EVENING.  
   
   LATER TONIGHT...A SECOND MCS MAY EVOLVE AS STORMS DEVELOP OVER SRN
   KS/NRN OK INVOF THE SURFACE FRONT...AND EVENTUALLY EXPAND IN
   COVERAGE AND MERGE AS A LOW-LEVEL JET RE-INTENSIFIES THIS EVENING
   OVER OK AND THEN VEERS WITH TIME OVERNIGHT AND NOSES INTO MO.  ALONG
   WITH SOME CONTINUED TORNADO POTENTIAL...DAMAGING WINDS AND LARGE
   HAIL CAN BE EXPECTED WITH THIS SECOND MCS.
   
   FARTHER S...STORMS SHOULD DEVELOP NEAR/AHEAD OF A DRYLINE MIXING EWD
   ACROSS THE WRN HALF OF TX.  WITH SHEAR SUFFICIENT FOR ROTATING
   STORMS...LARGE HAIL AND LOCALLY-DAMAGING WINDS CAN BE EXPECTED WITH
   ISOLATED STRONGER/SUPERCELL STORMS THROUGH THIS EVENING.
   
   ISOLATED STRONGER CELLS MAY ALSO DEVELOP IN WEAK UPSLOPE FLOW REGIME
   OVER NERN CO.  LOCALLY-DAMAGING WIND GUSTS AND/OR HAIL WILL BE
   POSSIBLE WITH ISOLATED CELLS THROUGH THIS EVENING.
   
   ...OH VALLEY/APPALACHIANS INTO THE MID-ATLANTIC REGION...
   SCATTERED SEVERE THUNDERSTORMS CONTINUE ACROSS PARTS OF CENTRAL/SERN
   NY INVOF THE SURFACE COLD FRONT...AND SWD INTO SERN PA NEAR THE N-S
   WARM FRONT.  WITH ROUGHLY 1000 TO 2000 J/KG MIXED-LAYER CAPE ACROSS
   THIS REGION AND AMPLE SHEAR FOR ORGANIZED/ROTATING STORMS...EXPECT
   THE SEVERE POTENTIAL -- PRIMARILY IN THE FORM OF DAMAGING WINDS AND
   HAIL -- TO CONTINUE INTO THIS EVENING BEFORE SLOW DIURNAL WEAKENING
   COMMENCES.  
   
   FARTHER SWWD ALONG THE COLD FRONT INTO SWRN PA/WV/SRN OH...AND SWD
   INTO THE VA AND THE CAROLINAS...MORE DISORGANIZED
   PULSE/MULTICELL-TYPE STORMS CONTINUE TO DEVELOP.  WHILE WEAKER SHEAR
   WILL CONTINUE TO LIMIT STORM LONGEVITY...MOIST/MODERATELY-UNSTABLE
   ENVIRONMENT /2000 TO 3000 J/KG MIXED-LAYER CAPE/ WILL SUPPORT
   BRIEF/VIGOROUS UPDRAFTS -- AND ASSOCIATED THREAT FOR HAIL AND/OR
   DAMAGING GUSTS THROUGH EARLY TO MID EVENING.
   
   ..GOSS.. 06/09/2009
   
   .PREV DISCUSSION... /ISSUED 1128 AM CDT TUE JUN 09 2009/
   
   ...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.
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z