SWODY1
SPC AC 041953
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0253 PM CDT THU OCT 04 2007
VALID 042000Z - 051200Z
..THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON AND TONIGHT OVER
PORTIONS OF THE UPPER MS AND MID MO VALLEYS...
..UPPER MS INTO MID MO VALLEYS...
EARLY AFTERNOON MESOANALYSIS SHOWED SURFACE LOW OVER WRN KS WITH
QUASI-STATIONARY BOUNDARY EXTENDING NEWD THROUGH CNTRL NEB...SERN SD
INTO CNTRL MN. CONSIDERABLE LOW CLOUDINESS HAS PERSISTED OVER
PORTIONS OF CNTRL/ERN NEB WHICH HAS ALLOWED FOR THE DEVELOPMENT OF A
DIFFERENTIAL HEATING/BAROCLINIC ZONE FROM N-CNTRL KS TO
E-CNTRL NEB.
SHORT WAVE TROUGH OVER THE OK/TX PNHDLS INTO SWRN KS CONTINUES TO
LIFT NEWD THIS AFTERNOON WITH IMPLIED ZONE OF FORCING FOR ASCENT
GRADUALLY SHIFTING NEWD THROUGH NRN KS AND SRN NEB. LATEST SHORT
TERM MODEL GUIDANCE SUGGESTS THAT SURFACE-BASED STORM DEVELOPMENT
WILL BECOME INCREASINGLY LIKELY BY LATE AFTERNOON INTO EARLY EVENING
INVOF ABOVEMENTIONED BOUNDARIES OVER N-CNTRL/NERN KS INTO ERN
NEB...PERHAPS AS THIS FORCING FOR ASCENT ACTS ON DESTABILIZING AIR
MASS.
GOES SOUNDER PW LOOP AND TRENDS IN SURFACE OBSERVATIONAL DATA SHOW
THAT CONSIDERABLE LOW-LEVEL MOISTURE RETURN IS OCCURRING OVER ERN
NEB/WRN IA WHICH WHEN COUPLED WITH DAYTIME HEATING...SHOULD
CONTRIBUTE TO MLCAPES OF 1000-1500 J/KG FROM VICINITY OF WARM
FRONT/DIFFERENTIAL HEATING BOUNDARY SWD INTO KS. AREA PROFILERS
INDICATE THAT VERTICAL SHEAR REMAINS SOMEWHAT MARGINAL FOR STORM
ORGANIZATION WITH DEEP LAYER VERTICAL SHEAR OF GENERALLY LESS THAN
25-30 KT. STILL...SOME POTENTIAL WILL EXIST FOR A FEW
STRONG/MARGINALLY SEVERE STORMS WITH A THREAT OF MAINLY DAMAGING
WINDS/LARGE HAIL.
AS LLJ STRENGTHENS TONIGHT...ELEVATED TSTMS WILL BECOME INCREASINGLY
NUMEROUS FROM NERN NEB/NWRN IA INTO ERN SD AND SRN MN. FORECAST
SOUNDINGS INDICATE THE PRESENCE OF RELATIVELY STEEP LAPSE RATES AND
MODEST LOW-LEVEL MOISTURE ABOVE FRONTAL INVERSION WITH MUCAPES OF
1000-1500 J/KG. THIS INSTABILITY COMBINED WITH 30-35 KT OF SHEAR
THROUGH THE CLOUD-BEARING LAYER SUGGEST A THREAT OF
ORGANIZED/ROTATING STORMS CAPABLE OF MAINLY SEVERE HAIL.
..CNTRL/SRN HIGH PLAINS...
LEE TROUGH/WEAK DRYLINE IS SHARPENING THIS AFTERNOON FROM SURFACE
LOW OVER WRN KS SWD INTO WRN TX WITH VISIBLE SATELLITE IMAGERY
DEPICTING GROWING CUMULUS CONVECTION ALONG AND E OF THIS FEATURE.
SUSTAINED CONVERGENCE ALONG THIS BOUNDARY ALONG WITH INFLUENCE OF
SHORT WAVE TROUGH LIFTING NEWD THROUGH KS SHOULD SUPPORT THE
DEVELOPMENT OF ISOLATED/SCATTERED STORMS BY LATE AFTERNOON. THE
COMBINATION OF MODERATE INSTABILITY /MLCAPES OF 1000-1500 J PER KG/
AND MODEST VERTICAL SHEAR /EFFECTIVE BULK SHEARS OF 25-30 KT/
INDICATE SOME THREAT FOR A COUPLE OF SEVERE STORMS CAPABLE OF HAIL
AND LOCALLY DAMAGING WINDS.
..AZ...
SCATTERED TSTMS ARE ONGOING THIS AFTERNOON...MAINLY N OF THE
MOGOLLON RIM IN ASSOCIATION WITH SHEARED...LOW-LATITUDE SHORT WAVE
TROUGH/VORTICITY MAXIMUM LIFTING NEWD THROUGH THE LOWER CO VALLEY.
12Z TUS/FGZ SOUNDINGS INDICATED THAT MID-LEVEL LAPSE RATES ARE
RELATIVELY WEAK...HOWEVER DAYTIME HEATING AND PW VALUES OF 0.8-1.3
INCHES ARE CONTRIBUTING TO POCKETS OF MODERATE INSTABILITY WITH
SBCAPES OF 1000-1500 J/KG. THIS INSTABILITY COUPLED WITH MODEST
DEEP LAYER VERTICAL SHEAR /EFFECTIVE BULK SHEARS OF 30-40 KT/ SHOULD
SUPPORT THE DEVELOPMENT OF A FEW ORGANIZED STORMS THIS AFTERNOON AND
EVENING WITH LOCALLY STRONG WIND GUSTS AND SOME HAIL BEING THE
PRIMARY SEVERE WEATHER HAZARDS.
.MEAD.. 10/04/2007
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