[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 121231
SWODY1
SPC AC 121229

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0629 AM CST SUN MAR 12 2006

VALID 121300Z - 131200Z

...THERE IS A HIGH RISK OF SVR TSTMS OVER NRN/CENTRAL MO...FAR SERN
IA INTO W-CENTRAL IL...

...THERE IS A MDT RISK OF SVR TSTMS FROM ERN PORTIONS OF THE
SRN/CENTRAL PLAINS INTO THE MID SOUTH/OH RIVER VALLEY...

...THERE IS A SLGT RISK OF SVR TSTMS OVER A LARGE PORTION OF THE
NATION/S MID SECTION...

...SIGNIFICANT SEVERE THUNDERSTORM OUTBREAK STILL ANTICIPATED
TODAY... 

OVERNIGHT MODELS ARE CONSISTENT IN SLOWING DOWN APPROACHING
SHORTWAVE TROUGH AND ASSOCIATED SURFACE LOW.  06Z NAM AND GFS ALONG
WITH 09Z RUC DEVELOP SURFACE LOW INTO NWRN KS THRU 21Z...WHICH WILL
MOVE ACROSS NWRN MO EARLY THIS EVENING AND INTO SRN WI OVERNIGHT. 
THUS WILL SHIFT SEVERE THREAT AREAS A BIT WEST AS COMPARED TO
EARLIER OUTLOOK.

ELEVATED SUPERCELLS AND MULTICELL CLUSTERS ONGOING ACROSS PORTIONS
OF CENTRAL AND ERN KS THIS MORNING WILL LIKELY PERSIST AND SPREAD
ENEWD ACROSS THE MO RIVER VALLEY THIS AFTERNOON ALONG LLJ AXIS.
LARGE HAIL...SOME OF WHICH COULD BE VERY LARGE...MAY ACCOMPANY THIS
ACTIVITY.  THE EARLY DEVELOPMENT EAST OF THE DRY LINE RAISES SOME
CONCERN ABOUT QUALITY OF AIR MASS AVAILABLE FOR LATER SEVERE THREAT.
 HOWEVER...AIR MASS WILL RECOVER QUICKLY EAST AND SOUTH OF THIS
ACTIVITY WITH SURFACE DEW POINTS WELL INTO THE 60S EXPECTED ALONG
AND NORTH OF THE MO RIVER VALLEY BY 21Z...AS WRN END OF OUTFLOW
BOUNDARY CURRENTLY NEAR THE OZARKS ERODES.  WITH AFTERNOON
HEATING...SRN AND ERN MOST STORMS WILL BECOME INCREASINGLY SURFACE
BASED DURING THE EARLY TO MID AFTERNOON...WITH ADDITIONAL
DEVELOPMENT INTO SERN KS/NERN OK ALONG DRY LINE.  LOW AND DEEP LAYER
SHEAR REMAINS MORE THAN OPTIMAL FOR TORNADIC SUPERCELLS WITH VERY
LARGE HODOGRAPHS.  THEREFORE...THE POTENTIAL FOR LONG-TRACK
TORNADOES WILL SPREAD EWD ACROSS MUCH OF MO/POSSIBLY FAR SERN IA AND
INTO WRN IL THROUGH THE EVENING.  MOST LIKELY AREA WILL CONTINUE TO
BE NEAR AND JUST SOUTH OF EFFECTIVE WARM FRONT WHICH IS EXPECTED TO
LIFT NWD AHEAD OF APPROACHING LOW CENTER TO NEAR THE IA/MO BORDER BY
THIS EVENING. HERE LOW LEVEL SSELY WINDS WILL BE MAXIMIZED...AND AN
OUTBREAK OF DAMAGING TORNADIC SUPERCELLS IS MORE LIKELY.  AS STORMS
CROSS THE WARM FRONT AND DEVELOP NWD WITHIN ENHANCED ASCENT INTO
MORE OF IA...EFFECTIVE SHEAR WILL REMAIN SUFFICIENT FOR ELEVATED
SUPERCELLS ENHANCING THE THREAT OF VERY LARGE HAIL.  ACTIVITY WILL
CONTINUE WELL INTO THE NIGHT EWD ACROSS THE MID MS RIVER
VALLEY...WITH CONTINUED THREAT OF TORNADOES WHERE STORMS CAN ROOT
NEAR THE SURFACE ALONG AND SOUTH OF THE WARM FRONT.

FARTHER SOUTH INTO ERN OK AND NERN TX...INITIATION SHOULD BE DRIVEN
BY HEATING AND CONVERGENCE ALONG AND AHEAD OF DRY LINE AS CAPPING
HOLDS FOR MUCH OF THE DAY.  THOUGH THIS REGION WILL REMAIN REMOVED
FROM GREATEST LARGE SCALE ASCENT...FORECAST SOUNDINGS INDICATE A
VERY VOLATILE COMBINATION OF 2000+ J/KG MLCAPES AND 50+ KT EFFECTIVE
BULK SHEAR.  IN ADDITION...STORMS SHOULD REMAIN DISCRETE. 
THEREFORE...TORNADIC SUPERCELL THREAT...INCLUDING THE THREAT OF
LONG-LIVED TORNADOES AND VERY LARGE HAIL WILL SPREAD ACROSS SRN
MO/AR AND INTO THE LOWER OH RIVER VALLEY WELL AFTER DARK.

..EVANS/GRAMS.. 03/12/2006