[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 111624
SWODY1
SPC AC 111622

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1022 AM CST SAT MAR 11 2006

VALID 111630Z - 121200Z

...THERE IS A MDT RISK OF SVR TSTMS ERN OK...MUCH OF AR NEWD INTO
SRN/ERN MO SRN IL...

...THERE IS A SLGT RISK OF SVR TSTMS ERN SRN PLAINS NEWD INTO NRN MS
VALLEY AND WRN OH AND TN RIVER VALLEYS...

...THERE IS A SLGT RISK OF SVR TSTMS COASTAL AREAS OF SRN CA...

...SYNOPSIS...
LARGE COLD TROUGH OVER WRN U.S. WITH A VERY STRONG POLAR JET
EXTENDING AROUND TROUGH FROM SRN CA ENEWD ACROSS CENTRAL PLAINS TO
GREAT LAKES. EMBEDDED FAST MOVING S/WV TROUGHS MOVING ALONG THE JET
WITH ONE EXITING NEWD THRU NRN MS VALLEY...ANOTHER WEAKER IMPULSE
SRN HIGH PLAINS WHILE THE MAIN TROUGH AMPLIFIES FURTHER OVER SWRN
U.S.

AT THE SURFACE...LOW IN MN MOVES NEWD INTO WRN ONTARIO WITH TRAILING
COLD FRONT THRU ERN KS THEN WSWWD INTO TX PANHANDLE.  FRONT MOVES
INTO WRN GREAT LAKES THIS EVENING WHILE WRN PORTION STALLS AS
PRESSURES FALL AGAIN LEE OF CENTRAL ROCKIES AHEAD OF MAJOR WRN
TROUGH. DRY LINE INITIALLY ERN KS CENTRAL OK/NRN TX WILL MIX A
LITTLE E BY THIS AFTERNOON.

RICH GULF AIR MASS HAS BEEN SURGING NWD OVERNIGHT THRU ERN SRN
PLAINS/LWR/MID MS VALLEY AND COMBINED WITH WARM ADVECTION ON STRONG
LLJ...PRODUCED LARGE AREA OF THUNDERSTORMS NOW OVER OH VALLEY.

...CENTRAL U.S...
WITH LEAD TROUGH MOVING NEWD INTO SRN CANADA...NO STRONG UPPER
IMPULSE TO KEY ON TODAY ACROSS CENTRAL U.S. WHERE THE AIR MASS WILL
BE RAPIDLY DESTABILIZING.  HOWEVER THE STRONG DEEP LAYER SHEAR
ASSOCIATED WITH THE VIGOROUS POLAR JET DOES SUPPORT DEVELOPMENT OF
SEVERE THUNDERSTORMS OVER A LARGE AREA E OF COLD FRONT AND DRY LINE
BEGINNING BY MID AFTERNOON.

WITH MID/UPPER 60 DEWPOINTS SURGING NWD INTO MID MS/LWR OH VALLEYS
BY THIS AFTERNOON ALONG WITH 7 C/KM PLUS LAPSE RATES...MLCAPES
EXPECTED TO RANGE FROM 1500 J/KG MID MS VALLEY TO ABOVE 2000 J/KG AR
SWD THRU LOWER MS VALLEY/ERN SRN PLAINS.

THE WEAK IMPULSE MOVING OUT OF TX COUPLED WITH STRONG HEATING AND
GENERALLY WEAK CONVERGENCE SUGGESTS STORM INITIATION WILL OCCUR
VICINITY COLD FRONT AND DOWN DRY LINE FROM MO INTO ERN OK BY
MID/LATE AFTERNOON.  SUPERCELLS ARE EXPECTED AS DEEP LAYER SHEAR
WILL BE IN EXCESS OF 50KT WITH LOW LEVEL ENHANCED SHEAR PARTICULARLY
VICINITY THE SUBTLE WARM FRONT THAT WILL LIE ACROSS MID MS VALLEY.

WHILE VERY LARGE HAIL WILL BE MOST COMMON THREAT...THE SHEAR AND
INSTABILITY ALSO SUPPORT TORNADOS WITH POSSIBLY OF A COUPLE STRONG
TORNADOES BY THIS EVENING.

HAVE EXPANDED THE MDT RISK NWD INTO MID MS VALLEY BASED ON EXPECTED
GREATER DESTABILIZATION INTO THIS AREA THAN ORIGINALLY FORECASTED.

SEVERE THUNDERSTORMS WILL CONTINUE AFTER DARK SPREADING EWD ACROSS
OH VALLEY AND WRN TN VALLEY WITH SLOW LESSENING OF POTENTIAL
OVERNIGHT WITH SURFACE STABILIZATION.

...SRN CA...
THE VERY COLD STORM SYSTEM REMAINS ALONG THE WEST
COAST...WITH STRONG LOW LEVEL SHEAR AND STEEP LAPSE RATES EXPECTED
NEAR THE SRN CA COAST. SMALL SUPERCELLS ARE LIKELY TO FORM OVER
RELATIVELY WARMER OFFSHORE WATERS WHERE INSTABILITY IS THE GREATEST
AND THEN MOVE ONSHORE...PARTICULARLY ORANGE/SAN DIEGO COUNTIES WHERE
STORMS WILL HAVE GREATEST OVERWATER TRAJECTORY.  IN ADDITION TO HAIL
AND GUSTY WINDS...WATERSPOUTS AND BRIEF TORNADOES ARE POSSIBLE WITH
THESE MINI-SUPERCELLS.

..HALES/GUYER.. 03/11/2006