DAY48SVR: Nws Storm Prediction Center Norman Ok

ACUS48 KWNS 100955
SWOD48
SPC AC 100954

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0354 AM CST MON DEC 10 2012

VALID 131200Z - 181200Z

...DISCUSSION...
MEDIUM RANGE FORECAST GUIDANCE CONTINUES TO INDICATE STRONG UPPER
JET INTENSIFICATION ACROSS MUCH OF THE CENTRAL AND SOUTHERN TIER OF
THE U.S...WITH ANOTHER STRONG MID LATITUDE JET NOSING INLAND ACROSS
THE PACIFIC COAST DURING THIS FORECAST PERIOD. THIS WILL
UNDOUBTEDLY LEAD TO AN INCREASINGLY ACTIVE PATTERN...WITH EMBEDDED
SHORT WAVE IMPULSES SUPPORTING POTENTIAL FOR PERIODIC SIGNIFICANT
SURFACE CYCLOGENESIS FROM THE LEE OF THE CENTRAL AND SOUTHERN
ROCKIES EASTWARD TO THE ATLANTIC SEABOARD...WHICH PROBABLY WILL
BECOME SUPPORTIVE OF AT LEAST BOUTS OF STRONG/SEVERE STORM
DEVELOPMENT LATE THIS WEEK INTO NEXT WEEK.

THE INITIATION OF STRONG SURFACE CYCLOGENESIS APPEARS POSSIBLE AS
EARLY AS THIS COMING FRIDAY ACROSS PARTS OF THE CENTRAL/SOUTHERN
PLAINS...AS THE SHORT WAVE IMPULSE...NOW BEGINNING TO DIG TOWARD THE
PACIFIC COAST...FINALLY ACCELERATES INLAND. BASED ON THE 10/00Z
ECMWF AND GFS...SEVERE WEATHER POTENTIAL APPEARS GREATEST FROM PARTS
OF WEST CENTRAL TX THROUGH NORTHERN TEXAS AND SOUTHERN OKLAHOMA LATE
FRIDAY AFTERNOON AND EVENING...EASTWARD ACROSS ARKANSAS
OVERNIGHT...AND PARTS OF WESTERN AND MIDDLE TENNESSEE/NORTHERN
MISSISSIPPI AND NORTHERN ALABAMA SATURDAY. HOWEVER...THE SPREAD
AMONG THE MODEL ENSEMBLE FORECASTS HAS BEEN AND REMAINS SIZABLE
CONCERNING THIS SHORT WAVE FEATURE. ADDITIONALLY...WHILE IT DOES
APPEAR POSSIBLE THAT A SUBSTANTIVE RETURN FLOW OF MOISTURE COULD
DEVELOP OFF THE WESTERN GULF OF MEXICO AS THE SYSTEM
DEVELOPS...JUXTAPOSITION OF THE MORE FAVORABLE FORCING FOR UPWARD
VERTICAL MOTION AND BOUNDARY LAYER DESTABILIZATION IS FAR FROM
CERTAIN. PREDICTABILITY REMAINS TOO LOW TO CONFIDENTLY ASCERTAIN
THE POTENTIAL FOR A REGIONAL SEVERE WEATHER EVENT...AND GRAPHICALLY
DELINEATE AN AREA.

THEREAFTER...THE SPREAD AMONG THE VARIOUS MODELS AND MODEL ENSEMBLES
INCREASES FURTHER WITH SUBSEQUENT DEVELOPMENTS.

..KERR.. 12/10/2012

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