SPC AC 031731
   
   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1231 PM CDT FRI JUL 03 2009
   
   VALID 041200Z - 051200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL HIGH
   PLAINS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
   PLAINS...OZARKS AND MID-MS VALLEY...
   
   ...CNTRL HIGH PLAINS...
   AN UPPER-LEVEL RIDGE WILL REMAIN IN PLACE ACROSS THE ROCKIES THROUGH
   SATURDAY. AT THE SFC...A LEE TROUGH IS FORECAST FROM SE MT SSEWD
   INTO ERN WY AND ERN CO. THUNDERSTORMS SHOULD DEVELOP IN THE HIGHER
   TERRAIN AND ALONG THE SFC TROUGH AS SFC TEMPS WARM DURING THE DAY.
   THE ACTIVITY SHOULD EXPAND IN COVERAGE ESEWD ACROSS THE HIGH PLAINS
   INTO AN AXIS OF MODERATE INSTABILITY. FORECAST SOUNDINGS ALONG THIS
   AXIS AT 00Z GENERALLY SHOW 0-6 KM SHEAR VALUES IN THE 35 TO 40 KT
   RANGE MAINLY DUE TO SPEED SHEAR IN THE MID TO UPPER-LEVELS. THIS
   ALONG WITH STEEP MID-LEVEL LAPSE RATES COULD SUPPORT A FEW
   SUPERCELLS WITH LARGE HAIL POTENTIAL. THE GREATEST THREAT FOR
   ORGANIZED SEVERE SHOULD EXIST FROM ECNTRL WY SWD ACROSS ERN CO WHERE
   SFC DEWPOINTS SHOULD BE A BIT HIGHER THAN AREAS TO THE NORTH
   RESULTING IN SLIGHTLY GREATER INSTABILITY. ALTHOUGH LOW-LEVEL WINDS
   SHOULD BE RELATIVELY WEAK ACROSS THE REGION...0-3 KM LAPSE RATES
   EXCEEDING 3.0 C/KM COULD BE SUPPORTIVE OF ISOLATED DAMAGING WIND
   GUSTS WITH THE MORE PERSISTENT STORMS. VERTICAL SHEAR AND
   INSTABILITY ON MODEL FORECASTS GRADUALLY DROP WITH SWD EXTENT ACROSS
   PARTS OF CNTRL AND NRN NM WHERE A FEW MARGINALLY SEVERE STORMS MAY
   DEVELOP DURING THE LATE AFTERNOON.
   
   ...SRN PLAINS/OZARKS/MID-MS VALLEY...
   A LOW-AMPLITUDE UPPER-LEVEL TROUGH IS FORECAST TO MOVE ESEWD ACROSS
   THE MID-MS VALLEY SATURDAY AS A SFC LOW DRIFTS EWD ACROSS NRN MO AND
   SRN IL. A CLUSTER OF THUNDERSTORMS COULD BE ONGOING ALONG A WARM
   FRONT EAST OF THE LOW SATURDAY MORNING WITH THIS COMPLEX PERSISTING
   OR REDEVELOPING EWD INTO THE OH VALLEY BY AFTERNOON. OTHER
   THUNDERSTORMS SHOULD DEVELOP ALONG A COLD FRONT EXTENDING FROM
   SCNTRL MO WWD INTO ERN OK. THIS ACTIVITY SHOULD INCREASE IN COVERAGE
   MOVING SEWD ACROSS AN AXIS OF MODERATE INSTABILITY WHERE SFC
   DEWPOINTS ARE FORECAST TO BE IN THE UPPER 60S F. FORECAST SOUNDINGS
   ALONG THIS CORRIDOR AT 00Z SHOW 30 TO 40 KT OF FLOW IN THE LOW TO
   MID-LEVELS RESULTING IN SUFFICIENT VERTICAL SHEAR FOR SEVERE STORMS.
   MODEL FORECASTS SUGGEST THE DOMINANT STORM MODE COULD BE LINEAR
   WHICH IS SUPPORTED BY THE LATEST WRF/NAM/NAMKF MODELS. IN THIS
   CASE...WIND DAMAGE WOULD BE POSSIBLE WITH EMBEDDED LINE-SEGMENTS
   ESPECIALLY AS LOW-LEVEL FLOW INCREASES IN THE EARLY EVENING
   ASSOCIATED WITH A 30-40 KT LOW-LEVEL JET. HAIL WILL ALSO BE POSSIBLE
   WITH SUPERCELLS EARLY IN THE DEVELOPMENT OF THE LINE OR WITH
   ROTATING STORMS EMBEDDED IN THE LINE. IF A LINEAR MCS CAN PERSIST
   THROUGH THE MID-EVENING...THEN THE SEVERE PROBABILITIES MAY NEED TO
   BE UPGRADED FOR A MORE WIDESPREAD WIND DAMAGE THREAT. THE SEVERE
   THREAT SHOULD EXTEND WSWWD INTO OK AND THE FAR ERN TX PANHANDLE
   WHERE MODEL FORECASTS SHOW MODERATE INSTABILITY AND VERY STEEP
   LOW-LEVEL LAPSE RATES BELOW 700 MB.
   
   ...FLORIDA...
   A VERY MOIST AND UNSTABLE AIRMASS WILL BE IN PLACE ACROSS SOUTHERN
   AND CNTRL FLORIDA SATURDAY WITH SCATTERED THUNDERSTORMS DEVELOPING
   ALONG SEA BREEZE BOUNDARIES AND ACROSS THE PENINSULA BY MIDDAY.
   FORECAST SOUNDINGS AT 21Z ACROSS PARTS OF CNTRL FL SHOW MUCAPE
   VALUES AROUND 3000 J/KG WITH 0-3 KM LAPSE RATES APPROACHING 8.0
   C/KM. THIS COULD BE SUFFICIENT FOR ISOLATED DAMAGING WIND GUSTS IN
   SPITE OF THE WEAK SHEAR ENVIRONMENT.
   
   ..BROYLES.. 07/03/2009
   
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