SPC AC 200645
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1245 AM CST TUE JAN 20 2009
VALID 221200Z - 231200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
BREAKDOWN OF HIGH-AMPLITUDE WRN RIDGE/ERN TROUGH REGIME WILL
CONTINUE THROUGH DAY-3 PERIOD...AS SRN STREAM SPLIT FLOW PATTERN
DEVELOPS OVER SWRN/S-CENTRAL CONUS. LEADING SHORTWAVE TROUGH -- NOW
EVIDENT IN MOISTURE CHANNEL IMAGERY OFFSHORE CA BETWEEN 130W-140W --
WILL MOVE INLAND AROUND 23/12Z. TROUGH THEN IS FCST TO WEAKEN
SOMEWHAT AS IT CONTINUES EWD...MAINTAINING NEGATIVE TILT...AND
REACHING FROM NERN NV TO SWRN NM BY END OF PERIOD.
...SWRN CONUS...
ISOLATED TO WIDELY SCATTERED TSTMS MAY CARRY OVER FROM DAY-2...AND
ALSO DEVELOP DURING DAYLIGHT HOURS...OVER PORTIONS AZ. REGIME THEN
SHOULD SHIFT EWD TO SWRN NM. SVR POTENTIAL APPEARS TOO MRGL AND
CONDITIONAL ATTM FOR AOA 5-PERCENT PROBABILITIES. LOW LEVEL WAA AND
RIBBON OF ELEVATED MOISTENING BETWEEN 700-800 MB SHOULD DESTABILIZE
AIR MASS...IN TANDEM WITH MIDLEVEL ASCENT IMMEDIATELY AHEAD OF
SHORTWAVE TROUGH...TO YIELD MUCAPE 200-300 J/KG PRIOR TO TROUGH
PASSAGE. STRENGTH/COVERAGE OF SFC HEATING IS IN QUESTION BECAUSE OF
POTENTIAL FOR CLOUD COVER...HOWEVER POCKETS OF INSOLATION MAY
DESTABILIZE RELATIVELY DRY BOUNDARY LAYER ENOUGH TO YIELD SFC-BASED
CONVECTIVE PARCELS DURING AFTERNOON. LIMITING ORGANIZATIONAL FACTOR
BESIDES WEAK BUOYANCY WILL BE LACK OF MORE ROBUST LOW-MIDLEVEL
SHEAR.
..EDWARDS.. 01/20/2009
CLICK TO GET WUUS03 PTSDY3 PRODUCT
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0830Z
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