SWODY2
SPC AC 150555
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1155 PM CST SAT NOV 14 2009
VALID 161200Z - 171200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MID-UPPER LEVEL SHORTWAVE TROUGH -- NOW ANALYZED OVER UT/NRN AZ --
IS EXPECTED TO EVOLVE INTO CLOSED LOW OVER NWRN/N-CENTRAL OK AND
SWRN/S-CENTRAL KS BETWEEN 16/12Z-16/18Z...MOVING SLOWLY EWD TO WRN
OZARKS BY 17/12Z. BY THAT TIME...ACCOMPANYING/BROAD CYCLONE WILL BE
CUT OFF TEMPORARILY FROM MAIN ZONE OF PREVAILING WLYS. RELATED SFC
CYCLONE IS EXPECTED TO MOVE SLOWLY NEWD ACROSS AR EARLY IN
PERIOD...THEN HOOK NWWD ACROSS SERN MO TOWARD BECOMING MORE
VERTICALLY STACKED WITH MID/UPPER LEVEL LOW. TRAILING SFC COLD
FRONT IS FCST TO MOVE FROM COASTAL PLAIN QUICKLY OFFSHORE TX COAST
BY 16/18Z...AND EWD ACROSS LA/MS AND PORTIONS AL THROUGH END OF
PERIOD.
HEIGHTS ALOFT WILL BE FALLING OVER PAC NW THROUGH MUCH OF PERIOD AS
SERIES OF LOW-AMPLITUDE SHORTWAVES TRAVERSE SWLYS...IN ADVANCE OF
MORE POTENT/EXPANSIVE TROUGHING EXPECTED DAY-3. THUNDER POTENTIAL
INLAND APPEARS TOO ISOLATED/MRGL FOR GEN TSTM OUTLOOK OVER THAT
AREA.
...W GULF COASTAL PLAIN TO MS DELTA REGION...
BAND OF PRECIP AND EMBEDDED CONVECTION...WITH EPISODIC AND WIDELY
SCATTERED TSTMS...MAY BE ONGOING AT BEGINNING OF PERIOD INVOF
FRONTAL ZONE...BETWEEN ARKLATEX REGION AND S-CENTRAL TX. ACTIVITY
SHOULD SHIFT SEWD OFF TX COAST AND EWD ACROSS INLAND REGIONS E
TX/LA/SRN AR THROUGH DAYLIGHT HOURS. SERN PERIPHERY OF STG
MID-UPPER LEVEL WINDS ASSOCIATED WITH MID-UPPER CYCLONE SHOULD
EXTEND OVER FRONTAL ZONE AND SMALL PARTS OF ADJACENT WARM SECTOR --
E.G. ROUGHLY 50 KT AT 500 MB AND 80 KT AT 300 MB. THIS FLOW WILL
OVERSPREAD NARROW CORRIDOR OF RETURN-FLOW MOISTURE CHARACTERIZED BY
SFC DEW POINTS COMMONLY 60S F.
HOWEVER...SEVERAL FACTORS PRECLUDE UNCONDITIONAL SVR PROBABILITIES
ATTM. WITH MID-UPPER LEVEL CYCLONE BECOMING CUT-OFF...AND RELATED
LARGE-SCALE ASCENT BOTH WEAKENING AND REMAINING BEHIND SFC
FRONT...LAPSE RATES ALOFT WILL REMAIN VERY WEAK. BOUNDARY LAYER
LAPSE RATES ALSO WILL BE WEAK FOR MOST OF MORNING AND PERHAPS INTO
AFTERNOON DUE TO EFFECTS OF CLOUDS/PRECIP. ALTHOUGH THETAE
ADVECTION AND SUBTLE DIABATIC HEATING MAY BOOST LOW-LEVEL LAPSE
RATES DURING AFTERNOON...BY THAT TIME...LOW LEVEL CONVERGENCE WILL
BE WEAKENING INVOF FRONT WITH GENERALLY LIGHT AND INCREASINGLY SWLY
PREFRONTAL WINDS PROGGED AT SFC. 850 MB FLOW ALONG/AHEAD OF SFC
FRONT ALSO WILL BE WEAKENING WITH TIME FROM 16/12Z-17/00Z...REDUCING
BOTH HODOGRAPH SIZE AND LOW-LEVEL BULK SHEAR.
THEREFORE...CONVECTIVE COVERAGE AND STRENGTH SHOULD BE DECLINING IN
AREAS OF GREATEST INLAND THETAE.
..EDWARDS.. 11/15/2009
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