SWODY3
SPC AC 260730
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CDT WED MAR 26 2008
VALID 281200Z - 291200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
PROGRESSIVE MID/UPPER LEVEL PATTERN IS FCST TO CONTINUE THROUGH
PERIOD...FEATURING TWO PRIMARY SHORTWAVE TROUGHS IN NRN STREAM.
FIRST TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY NEAR COASTAL
PACIFIC NW -- IS EXPECTED TO CROSS NRN ROCKIES AND N-CENTRAL PLAINS
THROUGH DAY-2. PERTURBATION THEN SHOULD ACCELERATE EWD FROM UPPER
GREAT LAKES STATES ACROSS NEW ENGLAND BY END OF DAY-3 PERIOD.
ASSOCIATED SFC COLD FRONT WILL MOVE SEWD FROM LOWER/MIDDLE OH VALLEY
REGION ACROSS CENTRAL/SRN APPALACHIANS...TN VALLEY...AND MUCH OF
LOWER MS RIVER VALLEY THIS PERIOD. SWRN SEGMENT OF THIS FRONT
SHOULD DECELERATE LATE IN PERIOD OVER SOME PORTION CENTRAL/SRN TX.
DRYLINE SHOULD EXTEND FROM NERN MEX PIEDMONT NWD ACROSS SW TX TO
INTERSECTION WITH FRONT...AND WILL MARK WRN BOUND OF SIGNIFICANT
CONVECTIVE POTENTIAL. FRONTAL ZONE SHOULD WEAKEN AND RETREAT NWD
LATE IN PERIOD AS SFC CYCLOGENESIS OCCURS OVER NRN HIGH
PLAINS...AHEAD OF NWRN CONUS TROUGH.
FARTHER NW...SEVERAL SHORTWAVE COMPONENTS OF PERSISTENT GULF OF AK
LOW ARE PROGGED TO PHASE AND DIG SEWD. COMBINED PERTURBATION SHOULD
MOVE ASHORE PACIFIC NW EARLY IN DAY-3 PERIOD AS STG SHORTWAVE
TROUGH...PERHAPS WITH EMBEDDED/CLOSED LOW. TSTMS...PERHAPS WITH STG
GUSTS OR SMALL HAIL...MAY PRECEDE THIS FEATURE OVER INTERIOR PACIFIC
NW...ESPECIALLY INVOF STG LOW LEVEL COLD FRONT. HOWEVER...ANY
ASSOCIATED SVR POTENTIAL APPEARS TOO MRGL/CONDITIONAL FOR
PROBABILITIES THIS SOON.
..SRN PLAINS TO LOWER MS VALLEY...
CONSIDERABLE MODEL VARIEGATION IN FRONTAL PLACEMENT -- DISCUSSED IN
DAY-2 OUTLOOK -- LIKEWISE EXTENDS INTO AND INFLUENCES
LOCATION/TIMING OF DAY-3 CONVECTIVE POTENTIAL. BECAUSE OF
ASSOCIATED UNCERTAINTIES...AS WELL AS CAPPING CONCERNS AND FCST
WEAKNESS OF LOW LEVEL FLOW AND DEEP-LAYER SHEAR OVER ALMOST ANY
REASONABLE FRONTAL POSITION...WILL MAINTAIN LESS THAN CATEGORICAL
RISK OF SVR FOR THIS PERIOD. FAVORABLE FACTORS PRIMARILY INCLUDE
POTENTIAL FOR FRONTAL CONVERGENCE AND STG SFC HEATING TO WEAKEN
CINH...STEEP MIDLEVEL LAPSE RATES ASSOCIATED WITH ELEVATED MIXED
LAYER...AND BOUNDARY LAYER THETAE E OF DRYLINE SUITABLE FOR
STG/BRIEFLY SVR TSTMS. SFC DEW POINTS 60S F SHOULD BE COMMON ACROSS
SFC MOIST SECTOR...CONTRIBUTING TO POTENTIAL MLCAPES OVER 2000 J/KG
FOR ANY DIURNAL TSTMS THAT CAN DEVELOP ALONG FRONT.
.EDWARDS.. 03/26/2008
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