DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 221628
SWODY1
SPC AC 221625

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1125 AM CDT WED AUG 22 2012

VALID 221630Z - 231200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...

SHORT-WAVE TROUGH OVER THE NRN HIGH PLAINS WILL CONTINUE EWD INTO
THE UPPER MS VALLEY WHILE A LOWER-LATITUDE VORTICITY MAXIMUM
TRANSLATES FROM CNTRL CA INTO THE LOWER CO VALLEY. IN THE E...A
BROAD...LARGE-SCALE TROUGH WILL PROGRESS EWD TO ALONG THE ATLANTIC
SEABOARD. IN THE LOW LEVELS...A WEAK SURFACE LOW WILL DEVELOP
ACROSS SD IN TANDEM WITH A COLD FRONT ADVANCING THROUGH THE NRN HIGH
PLAINS INTO DAKOTAS AND WRN NEB.

...PARTS OF SD/MN INTO THE CNTRL HIGH PLAINS...

12Z SOUNDINGS AND SATELLITE-DERIVED PW IMAGERY INDICATE THAT THE
PRE-FRONTAL AIR MASS IS RELATIVELY DRY WHICH WILL MODULATE THE
DEGREE OF DESTABILIZATION. STILL...THE PRESENCE OF STEEP...LOW TO
MIDLEVEL LAPSE RATES WILL YIELD AFTERNOON MLCAPE OF 500-1000 J/KG.
ISOLATED-WIDELY SCATTERED TSTMS ARE EXPECTED TO DEVELOP LATER THIS
AFTERNOON INTO EVENING OWING TO LOW-LEVEL UPLIFT ALONG FRONT AND/OR
LEE TROUGH AND GLANCING INFLUENCE OF SHORTWAVE TROUGH. WHILE SOME
HAIL IS POSSIBLE...LOCALLY DAMAGING WIND GUSTS APPEAR TO BE THE
PRIMARY HAZARD DUE TO THE STEEP LAPSE RATES AND DRY...DEEPLY MIXED
SUB-CLOUD LAYER.

...GREAT BASIN/LOWER CO VALLEY...

DCVA AND ASSOCIATED MIDLEVEL COOLING ATTENDANT TO PROGRESSIVE
SHORTWAVE TROUGH WILL GIVE RISE TO AN INCREASE IN TSTM ACTIVITY
ACROSS THE REGION TODAY. THOUGH MID AND UPPER-LEVEL WIND FIELD WILL
STRENGTHEN SLIGHTLY...VERTICAL SHEAR AND INSTABILITY WILL REMAIN TOO
MARGINAL TO SUPPORT AN ORGANIZED SEVERE WEATHER EPISODE.
NONETHELESS...ISOLATED...SEVERE STORMS WILL REMAIN POSSIBLE WITH AN
ASSOCIATED RISK FOR LOCALLY STRONG WIND GUSTS AND SOME SMALL HAIL.

...E-CNTRL FL PENINSULA...

SIMILAR TO PREVIOUS DAYS...DEEP...WLY TROPOSPHERIC FLOW WILL
CONCENTRATE AFTERNOON STORM DEVELOPMENT ALONG EAST COAST SEA BREEZE
FRONT WITHIN A MOIST AND MODERATELY UNSTABLE ENVIRONMENT WITH MLCAPE
OF 1000-2000 J/KG. WHILE VERTICAL SHEAR AND LAPSE RATES WILL REMAIN
RATHER WEAK...THE PRESENCE OF A MOIST ENVIRONMENT WILL PROMOTE
WATER-LOADING IN CONVECTIVE DOWNDRAFTS AND THE POTENTIAL FOR LOCALLY
DAMAGING MICROBURSTS.

..MEAD/SMITH.. 08/22/2012

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