SWOD48
SPC AC 110955
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0355 AM CST SUN DEC 11 2011
VALID 141200Z - 191200Z
...PREDICTABILITY TOO LOW TO DELINEATE A REGIONAL SVR RISK AREA...
MEDIUM RANGE MODELS INDICATE THAT A VIGOROUS UPPER IMPULSE LIFTING
OUT OF THE SOUTHWESTERN STATES BY MIDWEEK WILL CONTRIBUTE TO
SIGNIFICANT SURFACE CYCLOGENESIS FROM THE CENTRAL PLAINS INTO THE
UPPER MIDWEST WEDNESDAY AND WEDNESDAY NIGHT. WITH THIS EXPECTED TO
COINCIDE WITH A SUBSTANTIVE INFLUX OF MOISTURE FROM THE WESTERN GULF
OF MEXICO...AN INCREASE IN CONVECTIVE POTENTIAL CERTAINLY SEEMS
LIKELY. SOME GUIDANCE...THE 11/00Z ECMWF IN PARTICULAR... SUGGESTS
THAT A DRY LINE OR DRY LINE TYPE STRUCTURE COULD FORM BENEATH A
MID-LEVEL DRY SLOT ACROSS PARTS OF CENTRAL INTO EASTERN OKLAHOMA AND
KANSAS BY LATE WEDNESDAY AFTERNOON...PROVIDING A POSSIBLE FOCUS FOR
SUPERCELL DEVELOPMENT IN THE PRESENCE OF STRONG VERTICAL SHEAR.
HOWEVER...EVEN IN THIS CASE...BOUNDARY LAYER DESTABILIZATION ALONG
AND AHEAD OF THE SURFACE FEATURE INTO PARTS OF ARKANSAS AND MISSOURI
REMAINS UNCLEAR. IT SEEMS MORE LIKELY THAN NOT THAT MOISTURE RETURN
ABOVE A RESIDUAL COOL BOUNDARY LAYER WILL PROMOTE CONSIDERABLE LOW
CLOUD COVER AND PRECIPITATION... MAINTAINING STABLE NEAR SURFACE
CONDITIONS. GIVEN THIS UNCERTAINTY...ALONG WITH LINGERING
DISCREPANCIES/SPREAD AMONG THE MODELS AND MODEL
ENSEMBLES...PREDICTABILITY REMAINS TOO LOW TO CONFIDENTLY ASSESS THE
POTENTIAL FOR A REGIONAL SEVERE WEATHER OUTBREAK. THIS UNCERTAINTY
GROWS THROUGH THE REMAINDER OF THE PERIOD...AS SHORT WAVE
DEVELOPMENTS WITHIN THE PREVAILING SPLIT UPPER FLOW PATTERN BECOME
INCREASINGLY UNCLEAR.
..KERR.. 12/11/2011
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