SWODY2
SPC AC 080536
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1236 AM CDT FRI AUG 08 2008
VALID 091200Z - 101200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER NRN ID/WRN MT...
...THERE IS A SLGT RISK OF SVR TSTMS OVER WRN/CNTRL KS...
...SYNOPSIS...
AN AMPLIFIED LARGE-SCALE PATTERN WILL PERSIST THROUGH THE DAY TWO
PERIOD...FEATURING A FULL-LATITUDE TROUGH OVER THE ERN
CONUS...RIDGING FROM THE SRN ROCKIES INTO CANADIAN PRAIRIES AND A
MORE PROGRESSIVE TROUGH MOVING THROUGH WRN CANADA AND THE PACIFIC
NW. IN THE LOW LEVELS...A LEE CYCLONE WILL SLOWLY DEVELOP SWD FROM
THE CNTRL INTO SRN HIGH PLAINS WITH ATTENDANT FRONTAL ZONE EXTENDING
SEWD THROUGH ERN TX. A COLD FRONT ACCOMPANYING PACIFIC NW TROUGH
WILL PUSH EWD THROUGH THE NRN INTERMOUNTAIN REGION INTO THE NRN HIGH
PLAINS. FINALLY...A COLD FRONT ASSOCIATED WITH A SHORT WAVE TROUGH
DIGGING SEWD THROUGH THE UPPER GREAT LAKES WILL MOVE SWD THROUGH THE
UPPER GREAT LAKES WITH THE WRN EXTENSION OF THIS BOUNDARY REMAINING
MORE QUASI-STATIONARY OVER THE NRN PLAINS.
...NRN ID/WRN MT...
MODEST MOISTURE /PW VALUES OF 0.75-0.90 INCH/ COUPLED WITH STEEP
LAPSE RATES WILL CONTRIBUTE TO AN INCREASINGLY UNSTABLE AIR MASS BY
AFTERNOON AHEAD OF COLD FRONT WITH SBCAPES APPROACHING 1000 J/KG.
TSTMS ARE EXPECTED TO INCREASE IN COVERAGE AND INTENSITY BY LATE
AFTERNOON OR EVENING AS OROGRAPHIC ASCENT COMBINES WITH FRONTAL
FORCING AND HEIGHT FALLS ASSOCIATED WITH UPPER TROUGH. FORECAST
HODOGRAPHS INDICATE 35-45 KT OF DEEP-LAYER SWLY SPEED SHEAR WHICH
WILL BE SUPPORTIVE OF A FEW ORGANIZED STORMS...INCLUDING MARGINAL
BOWING AND SUPERCELL STRUCTURES. HAIL AND DAMAGING WINDS WILL BE
THE PRIMARY SEVERE WEATHER THREATS THROUGH THE EVENING HOURS.
...WRN/CNTRL KS...
A NW-SE ORIENTED BAND OF TSTMS MAY BE ONGOING AT THE ONSET OF THE
FORECAST PERIOD ALONG COOL SIDE OF LOW-LEVEL BAROCLINIC ZONE FROM
NEB INTO OK. LATEST MODEL GUIDANCE SUGGESTS THAT RATHER STRONG
DIABATIC HEATING WILL OCCUR SATURDAY FROM SWRN KS INTO THE TX/OK
PNHDLS. THIS INSOLATION COMBINED WITH A MOIST BOUNDARY LAYER INVOF
FRONT /DEWPOINTS IN THE 60S TO LOWER 70S/ AND MODEST MIDLEVEL LAPSE
RATES WILL RESULT IN A MODERATELY UNSTABLE AIR MASS WITH MLCAPES
APPROACHING 1000-2000 J/KG. PERSISTENT LOW-LEVEL WAA IN CONCERT
WITH INCREASED FORCING FOR ASCENT ASSOCIATED WITH A VORTICITY
MAXIMUM /NOW OVER UT/ TURNING SEWD THROUGH THE CNTRL HIGH PLAINS
SHOULD CONTRIBUTE TO AN INCREASE IN STORM COVERAGE DURING THE
AFTERNOON ALONG THE BOUNDARY.
WHILE MID AND HIGH-LEVEL WIND FIELDS WILL NOT BE PARTICULARLY
STRONG...FORECAST HODOGRAPHS SHOW PRONOUNCED VEERING THROUGH THE
LOWEST 2-3 KM WITH RESULTANT DEEP-LAYER SHEAR OF 30-35 KT. AS
SUCH...POTENTIAL WILL EXIST FOR A FEW ROTATING STORMS WITH MODEL
GUIDANCE SUGGESTIVE OF UPSCALE GROWTH INTO AN MCS SATURDAY NIGHT.
HAIL AND DAMAGING WINDS APPEAR TO BE THE MAIN SEVERE WEATHER
THREATS.
...LOWER MI/WI...
MODEST BOUNDARY LAYER MOISTURE AND DAYTIME HEATING WILL CONTRIBUTE
TO A WEAKLY UNSTABLE AIR MASS SATURDAY WITH SBCAPES INCREASING TO
500-1000 J/KG. FRONTAL CONVERGENCE AND DEEP-LAYER FORCING FOR
ASCENT ASSOCIATED WITH SHORT WAVE TROUGH WILL RESULT IN AN INCREASE
IN STORM COVERAGE BY AFTERNOON WITH ACTIVITY MOVING/DEVELOPING SEWD.
VERTICAL SHEAR WILL REMAIN SOMEWHAT MARGINAL...BUT A FEW
STRONG/SEVERE STORMS CONTAINING GUSTY WINDS AND SOME HAIL ARE
POSSIBLE.
..MEAD.. 08/08/2008
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