[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 221553
SWODY1
SPC AC 221552

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1052 AM CDT FRI SEP 22 2006

VALID 221630Z - 231200Z

...THERE IS A MDT RISK OF SVR TSTMS FROM ERN OK  AND MUCH OF AR INTO
PARTS OF MO/IL AND FAR WRN KY/TN...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK FROM N
TX INTO THE OH RIVER VALLEY...

RATHER COMPLEX FORECAST TODAY AS SPECIFIC TIMING FOR GREATEST SEVERE
THREAT STILL UNCERTAIN.  EXTREME SHEAR WILL REMAIN IN PLACE OVER A
LARGE PART OF THE CENTRAL U.S...WITH MOST FOCUSED INTENSE SHEAR
REMAINING FROM THE ARKLATEX REGION NEWD ACROSS THE MID MS/LOWER OH
RIVER VALLEYS. THIS INTENSE SHEAR WILL OVERSPREAD A VERY MOIST
BOUNDARY LAYER AS 65+F SURFACE DEW POINTS ADVECT NNEWD INTO
CENTRAL/NRN IL.  OVERALL SETUP REMAINS QUITE FAVORABLE FOR AN
OUTBREAK OF SEVERE THUNDERSTORMS AND TORNADOES ACROSS A LARGE PART
OF THE CENTRAL U.S.

...THROUGH 20Z...
OUTFLOW BOUNDARY/EFFECTIVE TROPICAL WARM FRONT REMAINS FAIRLY WELL
DEFINED AT 15Z FROM WRN TN WSWWD INTO SERN-E-CENTRAL OK...AND
MORNING SOUNDINGS WITHIN MOIST WARM SECTOR INDICATE LITTLE OR NO
CAPPING WITH TEMPERATURES IN THE LOWER 80S.  VWPS AND SHEAR ANALYSES
INDICATE VERY FAVORABLE LOW AND DEEP LAYER SHEAR FOR TORNADIC
SUPERCELLS...THOUGH OVERALL FOCUS FOR DEEP ASCENT APPEARS DIFFUSE
FOR MUCH OF THE DAY .  HOWEVER WITH INTENSE LOW PERSISTING OVER THE
MID MO/SWRN MN...SWLY LLJ WILL REMAIN IN PLACE INTO THE MID SOUTH
/H85 WINDS AROUND 40-45 KT/.  THUS...ISOLATED TORNADIC SUPERCELLS
MAY EVOLVE THROUGH THE DAY OVER AR INTO THE LOWER OH RIVER VALLEY. 
ACTIVITY WILL MOST LIKELY KEEP DEVELOPING WITHIN WARM AIR ALONG EDGE
OF STEEPER LAPSE RATES OVER ERN OK...WRN/CENTRAL AR AND MOVE QUICKLY
ENEWD INTO THE MID SOUTH.  NEWD EXTENT OF THREAT FROM AFTERNOON
ACTIVITY WILL BE HINDERED BY PERSISTENT CONVECTION/CLOUDS NOW
OVERSPREADING SERN MO AND THE LOWER OH RIVER VALLEY.

...LATER TODAY AND OVERNIGHT...
MORE VIGOROUS DEVELOPMENT CAN BE EXPECTED DURING THE MID TO LATE
AFTERNOON FROM PORTIONS OF NERN TX/NWRN LA/ERN OK INTO THE MID MS
RIVER VALLEY ALONG STRENGTHENING LOW LEVEL CONVERGENCE NEAR
INTENSIFYING SURFACE TROUGH/FRONT.  MODEL FORECASTS CONTINUE TO
DEVELOP AXIS OF MODERATE INSTABILITY WITHIN VERY MOIST BOUNDARY
LAYER INTO CENTRAL MO. IN ADDITION...SWLY LLJ WILL INCREASE LATE
TODAY AND THIS EVENING AS UPSTREAM IMPULSE DIGS SEWD INTO THE
CENTRAL ROCKIES AND LOW LEVEL TROUGH BECOMES BETTER DEFINED.  THIS
SHOULD MAINTAIN A THREAT OF STRONG TORNADOES AS SUPERCELLS AND SMALL
BOW ECHOES EVOLVE AND RACE ENEWD INTO/ACROSS THE MID MS RIVER VALLEY
LATER TODAY/OVERNIGHT  SEVERE THREAT MAY OCCUR IN SEVERAL BANDS
ACROSS WARM SECTOR GIVEN THE VERY WEAK INHIBITION...WITH DEVELOPMENT
CONTINUING/BACK-BUILDING TO THE WEST AHEAD OF EWD MOVING NE-SW
ORIENTED SURFACE TROUGH/FRONT.

..EVANS/CROSBIE.. 09/22/2006