SWODY1
SPC AC 031956
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0256 PM CDT THU SEP 03 2009
VALID 032000Z - 041200Z
...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING FROM
E-CNTRL CO INTO WRN AND CNTRL PARTS OF KS...
...CNTRL PLAINS...
HIGHER WIND/HAIL PROBABILITIES AND A CATEGORICAL SLIGHT RISK HAVE
BEEN INCLUDED IN THIS FORECAST ACROSS PARTS OF WRN/CNTRL KS AND ERN
CO.
19Z MESOANALYSIS INDICATED A SURFACE LOW E OF GLD WITH ASSOCIATED
COLD FRONT PUSHING SWD THROUGH ERN CO...S OF AN ITR-LIC LINE.
FARTHER E...A WEAK WARM FRONT/DIFFERENTIAL HEATING BOUNDARY WAS
ANALYZED FROM VICINITY OF LOW EWD TO N OF HLC AND THEN MORE SEWD TO
NEAR ICT. FINALLY A WEAK INVERTED TROUGH STRETCHED FROM
INTERSECTION OF WARM FRONT /NE OF HLC/ NNEWD TO NEAR GRI.
FORCING ASSOCIATED WITH WRN EXTENSION OF MIDLEVEL VORTICITY MAXIMUM
CURRENTLY OVER ERN NEB...IN CONJUNCTION WITH COLD FRONT...HAS
INITIATED A CLUSTER OF TSTMS OVER E-CNTRL CO AS OF 1930Z.
ADDITIONAL STORMS ARE LIKELY TO DEVELOP THIS AFTERNOON INTO EVENING
ALONG SWD-MOVING COLD FRONT...AS WELL AS WARM FRONT AND INVERTED
TROUGH FROM WRN KS INTO S-CNTRL NEB. WARM SECTOR AIR MASS IS
RELATIVELY MOIST WITH DEWPOINTS IN THE LOWER 60S. WHEN COUPLED WITH
STRONG DIABATIC HEATING...EXPECT BOUNDARY LAYER TO FURTHER
DESTABILIZE WITH MLCAPE APPROACHING 1000-2000 J/KG BY LATE
AFTERNOON.
CURRENT PROFILER/VWP DATA INDICATE A BELT OF MODEST /25-30 KT/ NWLY
MIDLEVEL FLOW PRESENT S OF ERN NEB VORTICITY CENTER WHICH IS
RESULTING IN 30-35 KT OF DEEP-LAYER SHEAR GIVEN THE BACKED SURFACE
WINDS OVER CNTRL KS ALONG WARM FRONT. THIS SETUP SHOULD FAVOR THE
DEVELOPMENT OF ORGANIZED MULTICELL OR MARGINAL SUPERCELL STRUCTURES
WITH THE THREAT FOR HAIL AND LOCALLY DAMAGING WIND GUSTS.
LOW POTENTIAL FOR A BRIEF TORNADO WILL ALSO EXIST ALONG INVERTED
TROUGH OVER N-CNTRL KS/S-CNTRL NEB WHERE LOW-LEVEL BUOYANCY AND
VORTICITY AXES COINCIDE. SEE MCD 1989 FOR FURTHER NEAR-TERM DETAILS
ON THIS AREA.
...SRN PLAINS...
CONSIDERABLE MORNING CLOUDS AND ELEVATED TSTM CLUSTERS HAVE
ESTABLISHED A PRONOUNCED BAROCLINIC ZONE EXTENDING FROM THE SRN TX
PNHDL ESEWD ALONG THE RED RIVER AND THEN SWD THROUGH ERN TX. STRONG
SURFACE HEATING S AND W OF THIS BOUNDARY HAS BOOSTED TEMPERATURES
INTO THE 90S...CONTRIBUTING TO MLCAPE OF 1000-1500 J/KG AND A
WEAKENING CAP.
WEAK LOW-LEVEL WAA AND CONVERGENCE ALONG THIS BOUNDARY HAVE RECENTLY
FOSTERED TSTMS E/SE OF CRS WITH THIS ACTIVITY LIKELY
MOVING/DEVELOPING SWD TOWARD THE GULF COAST. VISIBLE SATELLITE
IMAGERY SUGGESTS THAT ADDITIONAL STORM CLUSTERS WILL BE POSSIBLE
THIS AFTERNOON INTO EVENING ALONG THE REMAINING PORTION OF
BAROCLINIC ZONE /I.E. NWRN AND NRN TX/. MARGINAL VERTICAL SHEAR
WILL TEND TO LIMIT A MORE ORGANIZED SEVERE WEATHER THREAT.
HOWEVER...SOME HAIL AND/OR LOCALLY STRONG WIND GUSTS WILL BE
POSSIBLE WITH THE STRONGER STORMS.
..MEAD.. 09/03/2009
.PREV DISCUSSION... /ISSUED 1111 AM CDT THU SEP 03 2009/
...CENTRAL PLAINS INTO THE SRN HIGH PLAINS...
WEAKENING MID/UPPER LEVEL LOW OVER ERN NEB WILL CONTINUE SETTLING
SSEWD TODAY WITH ASSOCIATED SURFACE FRONT/TROUGH EXTENDING SW-NE
FROM SRN NEB INTO SERN CO. THIS FEATURE SHOULD FOCUS CONVERGENCE
AND AFTERNOON TSTM DEVELOPMENT AS HEATING WEAKENS CAPPING AND
PRODUCES MARGINAL TO MODERATE INSTABILITY FROM THE CENTRAL KS-NEB
BORDER SWWD INTO THE OK/TX PANHANDLE REGION AND NERN NM. WEAK SELY
SURFACE WINDS WILL SUPPORT MODERATE DEEP LAYER SHEAR AS REGION IS
OVERSPREAD BY 25-35 KT OF MID LEVEL NWLY WINDS. THIS SUGGESTS A FEW
MORE ORGANIZED/PERSISTENT STORMS...INCLUDING WEAK SUPERCELLS...
COULD EVOLVE THROUGH THE EARLY EVENING WITH ATTENDANT RISKS OF
MARGINALLY SEVERE HAIL/WIND. OVERALL SEVERE THREAT SHOULD WANE
AFTER DARK...ALTHOUGH CLUSTERS MAY PERSIST TONIGHT NEAR THE
MID/UPPER LEVEL LOW OVER CENTRAL/ERN KS AND TOWARDS THE RED RIVER
VALLEY/NWRN TX AS SUGGESTED BY LATEST NAM/GFS.
...N-CENTRAL/NERN TX AND FAR SRN OK...
SURFACE FRONT/OUTFLOW BOUNDARY SHOULD REMAIN IN PLACE OVER NERN TX
INTO SWRN OK/NWRN TX THIS AFTERNOON...WITH DEVELOPMENT OF MODERATE
INSTABILITY ANTICIPATED ALONG AND JUST TO ITS SOUTH BY THE LATE
AFTERNOON. ALTHOUGH FLOW ALOFT REMAINS QUITE WEAK...CONVERGENCE
NEAR THE FRONT AND WEAKENING CAP/INCREASING INSTABILITY SHOULD
SUPPORT TSTM DEVELOPMENT DURING THE MID TO LATE AFTERNOON. THIS
ACTIVITY WILL LIKELY DRIFT SLOWLY SSEWD WITH ATTENDANT THREATS OF
ISOLATED...BRIEF-LIVED SEVERE HAIL/WIND THROUGH THE EARLY EVENING.
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