SWODY3
SPC AC 230751
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0151 AM CST SAT FEB 23 2008
VALID 251200Z - 261200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
VERY PROGRESSIVE SRN BRANCH OF MID-UPPER LEVEL WLYS WILL PERSIST
THROUGH THIS PERIOD. PRIMARY FEATURE WITH THAT FLOW WILL BE STG
SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY W OF CA
BETWEEN 135W-140W. THIS PERTURBATION SHOULD MOVE ACROSS GREAT
BASIN/4-CORNERS REGION DAY-2...THEN EWD ACROSS CENTRAL/SRN PLAINS
AND MID MS VALLEY THIS PERIOD. BY ABOUT 26/00Z...AVAILABLE
OPERATIONAL PROGS AND STRONG CONSENSUS OF SREF MEMBERS INDICATES
POSITIVELY TILTED TROUGH FROM UPPER GREAT LAKES SWWD ACROSS SRN HIGH
PLAINS...MAIN DIFFERENCES BEING IN MAGNITUDE OF RELATIVE SHORTWAVE
STRENGTH IN MERGED NRN AND SRN BRANCHES OF FLOW.
SUCH MESOSCALE DIFFERENCES ALOFT MANIFEST THEMSELVES IN SFC PROGS ON
STRENGTH OF MAIN LOW....HOWEVER CONFIDENCE IS FAIRLY STG IN TRACK
FCST. SFC CYCLONE DEVELOPING IN CENTRAL PLAINS...PER DAY-2
OUTLOOK...SHOULD MOVE EWD ACROSS IL TO OH VALLEY AND LOWER GREAT
LAKES REGIONS BY END OF PERIOD. TRAILING COLD FRONT SHOULD MOVE
SEWD OVER OK/AR/MO...MOST OF TX...AND PARTS OF MS/TN/LA BY 26/12Z.
..SE TX TO WRN TN/MO BOOT-HEEL REGION...
CONDITIONAL POTENTIAL EXISTS FOR SVR TSTMS TO DEVELOP INVOF SFC
FRONT...PRIMARILY FROM LATE AFTERNOON THROUGH EVENING HOURS WHEN
COMBINATION OF LOW LEVEL WARM/MOIST ADVECTION...FAVORABLE DEEP-LAYER
SHEAR...FRONTAL FORCING AND AT LEAST MRGL INFLOW-LAYER MOISTURE MAY
BE BEST JUXTAPOSED. GREATER CONCENTRATION OF SVR THAN REFLECTED BY
CURRENT PROBABILITIES MAY DEVELOP WITHIN THIS SWATH...HOWEVER
SPATIAL/TIMING UNCERTAINTIES ON CONVECTIVE INITIATION NEED TO BE
RESOLVED BEFORE LARGER PROBABILITIES CAN BE DRAWN.
WARM SECTOR MOISTENING AHEAD OF SYSTEM IS EXPECTED TO BE INCOMPLETE
BECAUSE OF FCST TRAJECTORIES THAT EMANATE FROM CONTINENTAL
ANTICYCLONE THAT WILL SETTLE ACROSS ERN CONUS BEFORE DAY-3. THIS
WILL RESULT IN ONLY NARROW CORRIDOR OF PARTIAL MARINE MODIFICATION
IMMEDIATELY AHEAD OF SFC COLD FRONT. ALSO...GIVEN POSITIVE TILTING
OF TROUGH AND ASSOCIATED GEOMETRY OF STRONGEST MID/UPPER LEVEL
ASCENT BEHIND SFC FRONT...WARM SECTOR LAPSE RATES BY TIME OF MOST
PROBABLE STORM INITIATION WILL BE RELATIVELY WEAK. EXPECT CAPPING
OF MUCH OF WARM SECTOR DURING DAY...THOUGH TSTMS MAY DEVELOP ALONG
FRONT DURING AFTERNOON AND INCREASE FOR SEVERAL HORUS DURING
EVENING...W OF AXIS OF 40-50 KT LLJ. CONVECTION SHOULD WEAKEN AFTER
ABOUT 26/06Z AS STRONGEST DEEP-LAYER FORCING LIFTS AWAY FROM REGION
TO NE.
.EDWARDS.. 02/23/2008
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