ACUS01 KWNS 051224
SWODY1
SPC AC 051223
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0723 AM CDT SUN SEP 05 2010
VALID 051300Z - 061200Z
...NO SVR TSTM AREAS FORECAST...
...SRN MT/NRN WY INTO THE NRN PLAINS...
CONSIDERABLE AMPLIFICATION OF WRN CANADA/NWRN CONUS UPPER TROUGH IS
FORECAST THIS PERIOD AS POTENT VORTICITY MAXIMUM AND ASSOCIATED
50-60 KT MIDLEVEL JET STREAK PROGRESS FROM THE PACIFIC NW INTO
NRN/CNTRL HIGH PLAINS. THIS LARGE-SCALE PATTERN EVOLUTION WILL
RESULT IN NOTABLE HEIGHT FALLS --I.E. 50-100 M/12 H-- SPREADING
ESEWD THROUGH THE NRN INTERMOUNTAIN REGION INTO NRN HIGH PLAINS. AT
THE SURFACE...BROAD LEE CYCLONE NOW OVER WRN PARTS OF SD/NEB IS
FORECAST TO CONSOLIDATE AND UNDERGO DEEPENING WHILE DEVELOPING ESEWD
TO CNTRL NEB BY MONDAY MORNING. MEANWHILE...A TRAILING COLD FRONT
WILL PROGRESS SEWD THROUGH THE NRN HIGH PLAINS INTO THE WRN DAKOTAS
AND WRN NEB.
CLUSTERS OF TSTMS HAVE PERSISTED EARLY THIS MORNING OVER SRN PARTS
OF MT IN ADVANCE OF WEAKER MIDLEVEL PERTURBATION PRECEDING PRIMARY
SYSTEM MENTIONED ABOVE. SOME SMALL HAIL MAY ACCOMPANY THIS ACTIVITY
THROUGH THE REMAINDER OF THE MORNING...THOUGH NO ORGANIZED SEVERE
WEATHER IS ANTICIPATED. MORE INTENSE...DIURNALLY-ENHANCED STORMS
ARE FORECAST THIS AFTERNOON ALONG COLD FRONT FROM SRN/ERN PARTS OF
MT INTO NRN WY AS STRONGER DYNAMIC FORCING ATTENDANT TO AMPLIFYING
MIDLEVEL TROUGH BEGINS TO OVERSPREAD REGION.
PRE-FRONTAL AIR MASS IS EXPECTED TO REMAIN RATHER DRY WITH PW VALUES
AOB ONE INCH AND BOUNDARY LAYER DEW POINTS IN THE 40S. HOWEVER...
THE PRESENCE OF A STEEP LAPSE RATE ENVIRONMENT WILL YIELD MODEST
DESTABILIZATION THROUGH THE DIURNAL HEATING CYCLE WITH MLCAPE
APPROACHING 500-1000 J/KG. WHEN COUPLED WITH 40-50 KT OF DEEP WLY
SHEAR...SETUP WILL FAVOR THE DEVELOPMENT OF ISOLATED SEVERE STORMS
/INCLUDING EPISODIC SUPERCELL STRUCTURES/ WITH A RISK FOR SPORADIC
DAMAGING WIND AND HAIL. AN ISOLATED WIND/HAIL THREAT IS EXPECTED TO
DEVELOP EWD INTO THE WRN DAKOTAS TONIGHT IN ASSOCIATION WITH TSTMS
ONGOING ALONG COLD FRONT.
CURRENTLY...IT APPEARS THAT THE LIMITED MOISTURE AVAILABILITY AND
RESULTING MARGINAL CONVECTIVE INSTABILITY WILL PRECLUDE THE
DEVELOPMENT OF A MORE ORGANIZED SEVERE WEATHER EPISODE AND THE
NECESSITY FOR A CATEGORICAL SLIGHT RISK.
..MEAD/GRAMS.. 09/05/2010
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