SWODY1
SPC AC 071254
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0754 AM CDT WED OCT 07 2009
VALID 071300Z - 081200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
SLOWLY PROGRESSIVE SPLIT FLOW PATTERN WILL PREVAIL IN THE WEST THIS
PERIOD...WHILE BROAD SUBTROPICAL RDG PERSISTS OVER FL...AND LWR GRT
LKS TROUGH SWEEPS RAPIDLY E TO THE CANADIAN MARITIMES. POSITIVE
TILT CLOSED LOW NOW OVER SRN CA SHOULD OPEN AND MOVE E INTO AZ BY
12Z THU...INDUCING LEE CYCLOGENESIS OVER ERN CO...AND NWD
REDEVELOPMENT OF SFC FRONT NOW STALLING OVER S TX AND THE WRN GULF
CST.
...ERN NY/NEW ENG THROUGH LATE MORNING...
VORT MAX NOW OVER ERN OH IS BEGINNING TO IMPINGE ON SFC COLD FRONT
/ASSOCIATED WITH LARGER SCALE LWR GRT LKS UPR TROUGH/...NOW IN ERN
NY. CONTINUED E/ENE MOTION OF THE VORT SHOULD ACCELERATE FRONT OFF
THE MA CST BY LATE MORNING. A STRONG...DEEP...UNIDIRECTIONAL WLY
WIND FIELD WILL ACCOMPANY THE FAST-MOVING FRONT AND ATTENDANT
LOW-TOPPED CONVECTIVE BAND. INCREASING DPVA AND FORCED ASCENT ALONG
FRONT MAY ALLOW CONVECTIVE BAND TO PERSIST...EWD TO THE CST...
DESPITE VERY LIMITED INSTABILITY/NEARLY SATURATED ENVIRONMENT OVER
CNTRL/SRN NEW ENG. EMBEDDED STRONGER CELLS WITHIN THE CONVECTIVE
BAND MAY YIELD ISOLD SVR WIND GUSTS AND PERHAPS SMALL HAIL THROUGH
LATE MORNING.
...CSTL CAROLINAS/GA THIS AFTN...
TSTMS HAVE PERSISTED OVERNIGHT ALONG/AHEAD OF TRAILING COLD FRONT
FROM THE LWR MS VLY E INTO PARTS OF GA/UPSTATE SC. ADDITIONAL AREAS
OF STORMS SHOULD FORM ALONG/AHEAD OF FRONT AS BOUNDARY CONTINUES ESE
LATER TODAY. THE DIURNALLY-DRIVEN CONVECTION LIKELY WILL FOCUS IN
AREAS WELL-REMOVED FROM CURRENT ACTIVITY...I.E. FROM SRN LA E INTO
SRN GA...AND ALONG THE S ATLANTIC CST FROM SAV TO ILM. WEAK SHEAR
WILL LIMIT STORM STRENGTH ALONG THE GULF CST. BUT COMBINATION OF
MODERATE INSTABILITY...RICH MOISTURE...AND 40 KT DEEP WLY SHEAR ON
SRN FRINGE OF GRT LKS TROUGH MAY SUPPORT MORE SUSTAINED/ORGANIZED
STORMS...AND AN ISOLD SVR WIND THREAT...AHEAD OF FRONT ALONG THE S
ATLANTIC CST.
...W/SW TX INTO SE NM THIS AFTN/TONIGHT AND EARLY THU...
FRONT NOW STALLED OVER SW TX WILL BEGIN TO REDEVELOP N ACROSS THE
SRN PLNS LATER TODAY/TONIGHT AS LEE CYCLONE STRENGTHENS OVER ERN CO.
AXIS OF VERY MOIST AIR/WEAK INHIBITION WILL PERSIST ALONG AND S OF
BOUNDARY. WEAKLY CONVERGENT/UPSLOPE LOW LVL FLOW AND DIFFERENTIAL
HEATING SHOULD SUPPORT SCTD STORMS BY MID AFTN OVER THE HIGHER
TERRAIN FROM SW TX N/NW INTO SE NM. THIS ACTIVITY SHOULD CONTINUE
TO INCREASE AND MERGE INTO ONE OR MORE SLOWLY-MOVING CLUSTERS
TONIGHT THROUGH EARLY THU.
COMBINATION OF MODERATE INSTABILITY WITH GRADUALLY INCREASING /40-50
KT/ MID LVL SWLY FLOW MAY SUPPORT SUSTAINED MULTICELLS/ SUPERCELLS
THIS AFTN/EVE WITH ISOLD SVR HAIL/LOCALLY DMGG WIND. THIS THREAT
MAY CONTINUE...AND BE ACCOMPANIED BY LOCALLY HEAVY RAIN... AS
REGENERATIVE ACTIVITY DEVELOPS TONIGHT/EARLY THU ACROSS A LARGER
PART OF W TX.
...SRN HI PLNS OF TX TO OK/LOWER MO VALLEY TONIGHT/EARLY THU...
STRENGTHENING /40-50 KT/ LLJ OVER THE SRN PLNS AND INCREASING HEIGHT
FALLS DOWNSTREAM FROM CA/AZ UPR TROUGH WILL ENHANCE NEWD MOISTURE
TRANSPORT ATOP SHALLOW LAYER OF COOL/STABLE AIR N/E OF NWD-MOVING
WARM FRONT. THIS SHOULD RESULT IN A SUBSTANTIAL INCREASE IN
ELEVATED TSTMS TOWARD/AFTER 06Z FROM NW TX AND THE TX PANHANDLE ENE
INTO WRN/NRN OK...SRN/ERN KS AND MUCH OF MO. DEVELOPMENT OF WEAK TO
MODERATE ELEVATED BUOYANCY /500-1500 J PER KG/ AND 40+ KT
UNIDIRECTIONAL CLOUD LAYER SHEAR SUGGEST POTENTIAL FOR ISOLD TO
PERHAPS SCTD INSTANCES OF SVR HAIL.
..CORFIDI/SMITH.. 10/07/2009
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