SWODY1
SPC AC 101958
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0258 PM CDT WED SEP 10 2008
VALID 102000Z - 111200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF WRN AND CNTRL NEB
THROUGH SD...
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF SRN AND CNTRL
AZ...
...NEB AND SD...
THIS AFTERNOON A COLD FRONT EXTENDS FROM NW ND SWWD THROUGH SERN MT
AND INTO NRN WY. A PRE-FRONTAL TROUGH EXTENDS FROM SW ND THROUGH WRN
NEB. RUC AND WV IMAGERY SHOW A COUPLE MID LEVEL VORTICITY MAXIMA
EJECTING NEWD THROUGH THE CNTRL AND NRN HIGH PLAINS.
AN AXIS OF MODEST LOW LEVEL MOISTURE WITH DEWPOINTS IN THE UPPER 50S
TO AROUND 60 HAVE ADVECTED NWD THROUGH WARM SECTOR OVER THE ERN TWO
THIRDS OF NEB AND SD EAST OF SURFACE TROUGH. MID-LEVEL LAPSE RATES
AROUND 7-7.5 C/KM HAVE SPREAD OVER THE MOIST AXIS. THOUGH THE EML IS
NOT PARTICULARLY WARM...IT HAS CONTRIBUTED TO A CAP IN MUCH OF THE
WARM SECTOR DUE TO LOW CLOUDS AND THE RELATIVELY COOL BOUNDARY
LAYER. THE LOW CLOUDS HAVE BEEN GRADUALLY MIXING OUT FROM THE WEST
FROM SWRN SD THROUGH WRN NEB WHERE THE ATMOSPHERE IS DESTABILIZING
WITH MLCAPE FROM 1000-1500 J/KG EXPECTED BY EARLY EVENING.
STORMS SHOULD DEVELOP IN VICINITY OF THE PRE-FRONTAL TROUGH BY EARLY
EVENING WHERE SURFACE HEATING AND ASCENT ATTENDING THE SHORTWAVE
TROUGH WILL PROMOTE DESTABILIZATION AND WEAKENING CONVECTIVE
INHIBITION. ACTIVITY WILL SHIFT EAST OVERNIGHT WHERE STRENGTHENING
LOW LEVEL JET WILL ENHANCE LIFT IN VICINITY OF SEWD ADVANCING
BAROCLINIC ZONE. EFFECTIVE SHEAR OF 30-40 KT WILL SUPPORT POTENTIAL
FOR SOME ORGANIZED STORM STRUCTURES AND POSSIBLY SUPERCELLS WITH
INITIAL STORMS. ACTIVITY MAY EVOLVE INTO AN MCS OR MAY BECOME MORE
FOCUSED WITHIN FRONTAL ZONE OVERNIGHT. LARGE HAIL AND DAMAGING WIND
WILL BE THE MAIN THREATS THROUGH THE EVENING.
...AZ...
RICH LOW LEVEL MOISTURE WITH MID 60S DEWPOINTS HAS ADVECTED NEWD
THROUGH SWRN AZ FROM THE GULF OF CA. STRONG DIABATIC HEATING WILL
CONTINUE TO DESTABILIZE THE ATMOSPHERE WITH MLCAPE FROM 1000 TO 1500
J/KG FROM SW THROUGH W CNTRL AZ. STORMS SO FAR HAVE BEEN MOSTLY OVER
THE HIGHER TERRAIN...AND WV IMAGERY SHOWS SUBSTANTIAL MID-UPPER
LEVEL DRYING SPREADING INTO SRN AZ. SO THERE IS SOME CONCERN THAT
ENTRAINMENT COULD LIMIT STORM COVERAGE OVER SRN AZ. BULK SHEAR
AROUND 30 KT IS MARGINALLY SUPPORTIVE OF MID LEVEL UPDRAFT ROTATION.
LAPSE RATES AND BOUNDARY LAYER TEMPERATURE-DEWPOINT SPREADS WILL
SUPPORT A THREAT OF ISOLATED DAMAGING WIND WITH THE STRONGER STORMS
THAT DO DEVELOP. HAIL MAY ALSO ACCOMPANY THE STRONGER UPDRAFTS.
..DIAL/KISS.. 09/10/2008
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