SWODY2
SPC AC 221719
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1119 AM CST MON NOV 22 2010
VALID 231200Z - 241200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
IN MID-UPPER LEVELS...MEAN TROUGHING WILL BE MAINTAINED OVER WRN
CONUS...TRAVERSED BY STG/PROGRESSIVE SHORTWAVES. FIRST SUCH
SHORTWAVE TROUGH -- NOW ANALYZED OVER CENTRAL/NRN HIGH PLAINS...WILL
EJECT NEWD OVER NERN MN/LS/WI AND NWRN ONT REGION EARLY DAY-2.
MEANWHILE...INTENSE SHORTWAVE TROUGH AND EMBEDDED MID-UPPER LOW --
EVIDENT IN MOISTURE CHANNEL IMAGERY OVER ERN BC/WRN AB -- WILL
RETROGRADE SLIGHTLY DAY-1...DIGGING SSWWD ACROSS NRN/WRN WA...BEFORE
ELONGATING MERIDIONALLY AND TURNING EWD. BY END OF PERIOD...500 MB
CYCLONE SHOULD BE LOCATED OVER WRN MT/ERN ID/NWRN WY REGION...WITH
MAIN TROUGH NWD OVER NWRN MT AND SWD OVER WRN UT. DURING
24/00Z-24/12Z...MID-UPPER RIDGING WILL BUILD OVER MS VALLEY REGION
FROM GULF COAST NWD ACROSS MN/WI.
AT SFC...CYCLONE NOW OVER ERN IA IS FCST TO MOVE NEWD TO NEAR SRN
JAMES BAY BY START OF PERIOD. TRAILING COLD FRONT -- ANALYZED AT
15Z ACROSS NRN MO...SERN KS AND EXTREME NERN OK -- IS EXPECTED NEAR
ERI-LEX-MEM-TXK LINE AROUND 23/12Z...THROUGH WEAK FRONTAL-WAVE LOW
OVER NE TX...THEN SWWD ROUGHLY ALONG BALCONES ESCARPMENT TO NEAR
DRT. WITHIN 12 HOURS...TX SEGMENT OF FRONT SHOULD WEAKEN
CONSIDERABLY AND MOVE NWD...AS STG LEE TROUGHING OCCURS OVER
CENTRAL-NRN GREAT PLAINS IN ADVANCE OF NWRN CONUS UPPER SYSTEM.
REMAINDER OF FRONT THEN SHOULD EXTEND FROM NEW ENGLAND SWWD ACROSS
COASTAL MID-ATLANTIC AND SRN APPALACHIANS TO NRN MS. ALTHOUGH SOME
MESOSCALE DIFFERENCES ARE EVIDENT IN PROGGED PLACEMENT...STG
CONSENSUS OF OPERATIONAL/SREF PROGS FAVORS LEE CYCLONE BY 24/12Z
OVER CENTRAL HIGH PLAINS.
...CENTRAL APPALACHIANS TO LOWER MS VALLEY AND ARKLATEX...
PRIMARY CONVECTIVE POTENTIAL OVER OUTLOOK AREA INVOLVES TWO REGIMES
SEPARATED IN TIME BUT SOMEWHAT OVERLAPPING SPATIALLY...
1. MORNING TO AFTERNOON INVOF DECELERATING COLD FRONT. BAND OF
CONVECTION WITH ISOLATED TO WIDELY SCATTERED EMBEDDED TSTMS MAY BE
ONGOING FROM CENTRAL/NRN APPALACHIANS REGION SWWD OVER LOWER MS
VALLEY REGION...PERHAPS BACKBUILDING S OF FRONT OVER PORTIONS LA AND
SE TX. STRONGEST FRONTAL FORCING...LOW-LEVEL CONVERGENCE AND
LARGE-SCALE ASCENT WILL BE AROUND 23/12Z...DIMINISHING THROUGH
REMAINDER MORNING. BY TIME OF PEAK AFTERNOON HEATING...CAPPING
SHOULD BE WEAK INVOF FRONTAL ZONE. HOWEVER...WEAKENING TRENDS ALSO
WILL PERSIST WITH LOW-LEVEL FLOW AND CONVERGENCE...ALONG WITH MRGL
LAPSE RATES ALOFT...ACTING TO LIMIT INTENSITY/COVERAGE OF DIURNAL
CONVECTION. SVR POTENTIAL APPEARS TOO WEAK/CONDITIONAL FOR AOA 5%
PROBABILITIES.
2. LATE IN PERIOD...SUPPORTED BY STG LEE-SIDE PRESSURE/HEIGHT
FALLS...BROAD/PRONOUNCED LOW-LEVEL WAA REGIME THAT WILL BE IN PLACE
ACROSS MUCH OF CENTRAL CONUS. SFC MOISTURE SHOULD RETURN NWD ACROSS
E TX WITH DEW POINTS MID-60S F S OF WARM FRONT...POTENTIALLY
REACHING AS FAR N AS SE OK/NE TX AREA AND WWD OVER CENTRAL TX. AIR
MASS OVER MOST OF THIS AREA SHOULD REMAIN CAPPED...WITH LAPSE RATES
ALOFT BEING TOO WEAK TO SUPPORT TSTMS. HOWEVER...INCREASING THETAE
ABOVE SFC MAY SUPPORT CONVECTIVE DEVELOPMENT NEAR END OF PERIOD OVER
ARKLATEX REGION NWD TOWARD OZARKS...AND/OR EWD OVER WRN TN.
..EDWARDS.. 11/22/2010
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