SWODY2
SPC AC 051647
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1147 AM CDT SAT SEP 05 2009
VALID 061200Z - 071200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
PRIMARY FEATURE OF INTEREST DURING THE DAY TWO PERIOD IS STRONG
MID/UPPER-LEVEL TROUGH WHICH WILL PROGRESS EWD THROUGH WRN CANADA
AND THE NWRN CONUS. AT THE SURFACE...LOW PRESSURE ASSOCIATED WITH
THIS SYSTEM WILL CONCURRENTLY DEVELOP EWD THROUGH CNTRL/ERN
MT...ALONG PACIFIC COLD FRONT WHICH WILL MOVE FROM THE NRN ROCKIES
THROUGH NRN HIGH PLAINS.
...MT...
PRE-FRONTAL AIR MASS IS FORECAST TO REMAIN RELATIVELY DRY WITH
DEWPOINTS IN THE 40S /TO PERHAPS LOWER 50S ERN MT/ AND PW VALUES OF
GENERALLY LESS THAN AN INCH. HOWEVER...STEEPENING LOW TO MIDLEVEL
LAPSE RATES ASSOCIATED WITH DAYTIME HEATING AND EWD ADVECTION OF EML
WILL SUPPORT WEAK CONVECTIVE INSTABILITY ALONG FRONT BY LATE
AFTERNOON WITH MLCAPE AOB 500 J/KG.
GIVEN THE STRENGTH OF THE EML RELATIVE TO LOW-LEVEL MOISTURE
AVAILABILITY...IT APPEARS THAT FRONTAL ZONE WILL REMAIN CAPPED
THROUGH MUCH OF THE DIURNAL HEATING CYCLE. LATEST MODEL GUIDANCE
SUGGESTS THAT ISOLATED STORM DEVELOPMENT WILL BE MOST LIKELY BY
EVENING INTO SUN NIGHT OVER PARTS OF N-CNTRL/NERN MT WHERE SUSTAINED
CONVERGENCE ALONG FRONT AND DEEP ASCENT ASSOCIATED WITH UPPER SYSTEM
CAN LOCALLY OVERCOME CONVECTIVE INHIBITION. FORECAST SOUNDINGS
INDICATE A DEEPLY-MIXED BOUNDARY LAYER /EVEN INTO EVENING/...AND
GIVEN THE STRENGTHENING SWLY WIND FIELDS AHEAD OF MIDLEVEL
TROUGH...SOME THREAT WILL EXIST FOR LOCALLY STRONG WIND GUSTS AND
PERHAPS SOME HAIL.
..MEAD.. 09/05/2009
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