SWODY2
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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