SPC AC 050600
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0100 AM CDT TUE MAY 05 2009
   
   VALID 051200Z - 061200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF NORTH TX AND SRN
   OK...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN PLAINS
   AND LOWER MS VALLEY...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE ERN
   SEABOARD AND ERN GULF COAST STATES...
   
   ...SRN PLAINS...
   A WEST NORTHWEST FLOW PATTERN WILL BE IN PLACE ACROSS THE PLAINS
   STATES AS A LOW-LEVEL JET OVER WEST TX INCREASES MOISTURE FROM THE
   SOUTH TODAY. ELEVATED THUNDERSTORMS SHOULD BE ONGOING ON THE NOSE OF
   THE LOW-LEVEL JET IN WRN OK THIS MORNING WITH THIS ACTIVITY
   SPREADING EWD ACROSS CNTRL AND ERN OK DURING THE AFTERNOON. SOUTH OF
   THIS CLUSTER OF STORMS...MODEL FORECASTS SUGGEST THE WARM SECTOR
   WILL BE UNDISTURBED ALLOWING FOR SUBSTANTIAL DESTABILIZATION. WITH
   SFC DEWPOINTS IN THE MID TO UPPER 60S F ACROSS NORTH TX AND SRN
   OK...MODERATE TO STRONG INSTABILITY SHOULD DEVELOP WITH SFC-BASED
   CONVECTIVE INITIATION MOSTLY LIKELY IN SW OK OR NW TX DURING THE
   LATE AFTERNOON WITH A CLUSTER OF SEVERE STORMS DEVELOPING EWD DURING
   THE EARLY EVENING.
   
   NAMKF FORECAST SOUNDINGS ALONG THE RED RIVER AT 00Z WEDNESDAY SHOW
   AN IMPRESSIVE SHEAR AND THERMODYNAMIC ENVIRONMENT WITH 0-6 KM SHEAR
   OF 55 TO 60 KT AND MLCAPE VALUES APPROACHING 3000 J/KG. THIS ALONG
   WITH STEEP MID-LEVEL LAPSE RATES SHOULD BE SUPPORTIVE OF RAPID
   SUPERCELL DEVELOPMENT WITH VERY EFFICIENT HAIL PRODUCTION.  THE MORE
   DOMINANT SUPERCELLS COULD CONTAIN VERY LARGE HAIL. IN
   ADDITION...STRONG LOW-LEVEL SHEAR...LCL HEIGHTS BELOW 500 METERS AND
   DEWPOINTS IN THE UPPER 60S F SHOULD BE FAVORABLE FOR TORNADOES WITH
   THE POSSIBILITY OF A STRONG TORNADO AS THE LOW-LEVEL JET STRENGTHENS
   IN THE EARLY EVENING. WIND DAMAGE WILL ALSO BE POSSIBLE ESPECIALLY
   IF A TRANSITION TO A LINEAR MODE OCCURS DURING THE EVENING. AN
   ENHANCED WIND DAMAGE THREAT COULD EXIST FURTHER EAST ALONG THE
   INSTABILITY GRADIENT IF AN MCS ORGANIZES ACROSS NE TX INTO SW AR.
   
   ...ERN SEABOARD/GULF COAST STATES...
   AN UPPER-LEVEL TROUGH WILL MOVE NEWD ALONG THE ERN SEABOARD TODAY AS
   A LOW-LEVEL JET REMAINS IN PLACE FROM THE CAROLINAS NEWD INTO SERN
   VA. THUNDERSTORMS APPEAR LIKELY TO DEVELOP ONCE AGAIN ON THE WRN
   EDGE OF THE LOW-LEVEL JET IN THE HIGHER TERRAIN OF WRN SC AND CNTRL
   NC AS SFC TEMPS WARM. THIS CONVECTION SHOULD SPREAD NEWD INTO THE
   LOWER ELEVATIONS THIS AFTERNOON. FORECAST SOUNDINGS AT 21Z IN ECNTRL
   NC SHOW ABOUT 40 KT OF VERTICAL SHEAR WHICH SHOULD BE SUPPORTIVE OF
   SEVERE STORMS. 30 TO 40 KT OF LOW-LEVEL FLOW WITH SOMEWHAT
   UNIDIRECTIONAL WIND PROFILES ABOVE THE BOUNDARY LAYER SHOULD BE
   FAVORABLE FOR WIND DAMAGE. IF SUPERCELLS CAN DEVELOP WHERE
   INSTABILITY IS MAXIMIZED...THEN A LARGE HAIL THREAT WILL ALSO BE
   POSSIBLE.
   
   FURTHER SOUTHWEST ACROSS CNTRL AND ERN GA...THUNDERSTORMS SHOULD
   DEVELOP BEHIND THE AXIS OF THE UPPER-LEVEL TROUGH THIS AFTERNOON
   ALONG RESIDUAL OUTFLOW BOUNDARIES DUE TO SFC HEATING. MODERATE
   INSTABILITY...SFC DEWPOINTS NEAR 70 F AND 30 TO 40 KT OF VERTICAL
   SHEAR SHOULD BE SUPPORTIVE OF ISOLATED SEVERE STORMS. ISOLATED
   DAMAGING WIND GUSTS AND HAIL SHOULD OCCUR WITH THE STRONGER CELLS
   DURING THE AFTERNOON WHEN INSTABILITY WILL BE MAXIMIZED.
   
   ...CNTRL PLAINS...
   WEST TO NORTHWEST FLOW WILL REMAIN IN PLACE ACROSS THE CNTRL PLAINS
   TODAY. THIS AFTERNOON...THE MODELS FORECAST A NARROW AXIS OF
   INSTABILITY EXTENDING NNEWD FROM THE TX PANHANDLE INTO WRN KS AND
   SRN NEB. ALTHOUGH FORCING ACROSS THE INSTABILITY AXIS SHOULD REMAIN
   RATHER WEAK...A FEW STORMS SHOULD INITIATE DUE TO SFC HEATING AND
   LOW-LEVEL CONVERGENCE. FORECAST SOUNDINGS AT 00Z WEDNESDAY IN WRN KS
   SUGGEST MID-LEVEL LAPSE RATES WILL BE QUITE STEEP APPROACHING 8.0
   C/KM. THIS COMBINED WITH STRONG VERTICAL SHEAR SHOULD BE ENOUGH FOR
   A MARGINAL HAIL THREAT LATE THIS AFTERNOON OR EARLY THIS EVENING.
   
   ..BROYLES.. 05/05/2009
   
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