SWODY1
SPC AC 040449
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1149 PM CDT FRI OCT 03 2008
VALID 041200Z - 051200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MAIN SYNOPTIC FEATURE FOR THIS PERIOD WILL BE DEEPENING TROUGH
ACROSS WRN CONUS...EXTENDING SEWD FROM LARGE UPPER CYCLONE COVERING
MUCH OF AK. BROADER SCALE WRN TROUGHING WILL BE REINFORCED BY
SERIES OF LOW-AMPLITUDE SHORTWAVE PERTURBATIONS SE OF THAT NOW APCHG
WA/ORE COAST. STG SHORTWAVE TROUGH WILL MOVE SWD FROM ERN HUDSON
BAY AND DEEPEN ALMOST INTO CLOSE LOW OVER NERN ONT BY END OF PERIOD.
IN BETWEEN...CONUS PORTION OF MIDCONTINENTAL RIDGING IS FCST TO
BECOME PROGRESSIVELY SHORTER IN WAVELENGTH...RESEMBLING MORE
OMEGA-LIKE PATTERN WITH TIME AS HEIGHTS CONTINUE TO FALL ACROSS
GREAT BASIN AND ROCKIES...AND ANTICYCLONE STRENGTHENS OVER NRN MB.
AT SFC...LEE TROUGHING IS FCST TO STRENGTHEN CONSIDERABLY THROUGH
PERIOD...FROM MT TO TX PANHANDLE. DIFFUSE/SEGMENTED DRYLINE
DEVELOPMENT REASONABLY IS INDICATED BY SREF CONSENSUS OVER
CENTRAL/SRN HIGH PLAINS INVOF LEE TROUGH. BROAD WARM FRONTAL ZONE
-- NOW ANALYZED FROM SERN CO SEWD ACROSS SWRN OK...N-CENTRAL TX AND
CENTRAL LA...IS EXPECTED TO MOVE/REDEVELOP NWD THROUGH
TODAY...REACHING POSITION FROM NERN CO SEWD ACROSS CENTRAL/SERN KS
AROUND 5/00Z...THEN NWD TO W-CENTRAL SD AND SWRN IA 12 HOURS LATER.
PRONOUNCED RIDGING AND RESULTANT ANTICYCLONIC FLOW WILL PERSIST
ACROSS MS DELTA REGION SWWD INVOF TX COAST AND ADJACENT PORTIONS
NWRN GULF.
...OZARKS REGION...MORNING...
SCATTERED TSTMS ARE EXPECTED TO DEVELOP BEFORE 4/12Z ACROSS ERN
OK...AS ISENTROPIC LIFT AND MOISTURE TRANSPORT NEAR NOSE OF
VEERING/25-40 KT SWLY LLJ MOISTEN/DESTABILIZE AIR MASS ABOVE SFC.
ACTIVITY SHOULD PERSIST INTO FIRST FEW HOURS OF THIS
PERIOD...SHIFTING EWD/NEWD IN STEP WITH ZONE OF STRONGEST ISENTROPIC
ASCENT AND MOISTURE TRANSPORT. ELEVATED MUCAPES AND EFFECTIVE SHEAR
MAGNITUDES EACH SHOULD BE ON DECREASING TREND FROM 12Z ONWARD...BUT
STILL IN 500-1000 J/KG AND 35-45 KT RANGE RESPECTIVELY...IN SUPPORT
OF A FEW STG-SVR TSTMS. STORM-RELATIVE INFLOW ALSO WILL WEAKEN WITH
LOSS OF NOCTURNAL LLJ. THEREFORE...SVR HAIL POTENTIAL SHOULD BE
MARGINAL AND DIMINISHING BY 15Z.
...UPPER MS VALLEY REGION...NOCTURNAL...
SCATTERED TO WIDELY SCATTERED TSTMS...WITH MRGL HAIL POTENTIAL FROM
STRONGEST CORES...ARE POSSIBLE PRIMARILY FROM 06Z ONWARD IN
EWD-SHIFTING/EXPANDING WAA REGIME. ACTIVITY SHOULD BE ALIGNED
GENERALLY NW-SE...PARALLEL TO AND NE OF SFC WARM FRONT AND IN CLOSE
PROXIMITY TO WARM FRONT IN 850-700 MB LAYER. NEWD-TRENDING BRANCH OF
50-60 KT CENTRAL PLAINS LLJ WILL CONTRIBUTE TO DESTABILIZATION AND
HUMIDIFICATION OF AIR MASS ABOVE SFC...WITH INCREASING TENDENCY FOR
PARCELS TO BE LIFTED ISENTROPICALLY TO LFC. FCST SOUNDINGS SUGGEST
BOTH BUOYANCY AND SHEAR WILL BE TOO WEAK FOR ORGANIZED SVR...BUT
WITH ELEVATED MUCAPES 400-800 J/KG AND EFFECTIVE SHEAR IN 30-40 KT
RANGE...A FEW TSTMS WITH STG-SVR HAIL CANNOT BE RULED OUT.
...INTER-MTN W...
WIDELY SCATTERED TO SCATTERED TSTMS ARE EXPECTED ACROSS THIS
REGION...IN STEP WITH EWD SHIFT OF COLDEST AIR ALOFT. FCST
SOUNDINGS SUGGEST WARM MID-UPPER LEVEL AIR WILL INHIBIT LAPSE RATES
AND THUNDER POTENTIAL FOR MUCH OF DAY ACROSS CENTRAL/SRN ROCKIES AND
SRN HIGH PLAINS...BUT DESTABILIZATION ALOFT WILL SHIFT EWD AS RESULT
OF COMBINATION OF MIDLEVEL DPVA AND UPPER ASCENT ASSOCIATED WITH
LEFT EXIST REGION OF STRONGLY CYCLONIC 250 MB JET MAX. DURING LATE
AFTERNOON AND EVENING...LOW-MIDLEVEL SHEAR PROFILES WILL BE
FAVORABLE FOR SVR PRIOR TO WLY LOW LEVEL WIND SHIFT...WITH 35-50 KT
0-6 KM SHEAR IN FCST SOUNDINGS -- OVER WIDE AREA OF ERN GREAT BASIN
AND 4-CORNERS REGIONS INTO WRN PORTION SRN ROCKIES. HOWEVER...VERY
LIMITED BUOYANCY MAY JUST BARELY SUPPORT SUSTAINED DEEP CONVECTIVE
UPDRAFTS AMIDST STRENGTHENING WINDS ALOFT. GUSTY WINDS AT HIGHER
ELEVATIONS...AND SMALL HAIL...ARE POSSIBLE FROM ALMOST ANY
PERSISTENT TSTM OVER BROAD AREA. HOWEVER SVR POTENTIAL APPEARS TOO
MRGL...CONDITIONAL AND SPATIALLY DIFFUSE TO ASSIGN UNCONDITIONAL
PROBABILITY AREA AOA 5-PERCENT ATTM.
..EDWARDS/BOTHWELL.. 10/04/2008
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