[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 210537
SWODY2
SPC AC 210536

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1236 AM CDT THU SEP 21 2006

VALID 221200Z - 231200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM SERN KS/ERN OK...NEWD INTO
CNTRL IL...

...LOWER/MID MS VALLEY...SERN KS/ERN OK...

LATE EVENING MODEL GUIDANCE CONTINUE WITH DIVERGENT SOLUTIONS IN
REGARDS TO THE EVOLUTION OF MID U.S. UPPER TROUGH.  IT APPEARS THE
NAM MODEL IS TOO AGGRESSIVE MAINTAINING DOMINANCE OF LEAD UPPER LOW
OVER THE MID MO VALLEY AT THE EXPENSE OF STRONG UPSTREAM SPEED MAX
DIGGING INTO THE 4-CORNERS REGION.  GFS HAS BEEN VERY CONSISTENT
MAINTAINING TWO DISTINCT UPPER LOW/SHORTWAVE TROUGHS THROUGH THE
PERIOD.  LATEST THINKING IS THE LEAD SYSTEM WILL ROTATE NEWD INTO
THE GREAT LAKES BY 18Z FRI WITH TRAILING WARM CONVEYOR BELT AND LLJ
ACROSS THE MID MS VALLEY REGION EXPECTED TO GRADUALLY WEAKEN...BUT
REMAIN THE FOCUS FOR POTENTIAL SCATTERED THUNDERSTORM DEVELOPMENT
THROUGH THE PERIOD.  OF MUCH MORE CONCERN IS THE SPEED MAX THAT WILL
EJECT ACROSS THE SRN ROCKIES INTO KS DURING THE LATTER HALF OF THE
PERIOD.  THIS UPSTREAM SPEED MAX SHOULD INDUCE LEE CYCLOGENESIS OVER
THE TX PANHANDLE WHICH WILL THEN LIFT NEWD ALONG SHARPENING WARM
FRONT THAT WILL RETURN ACROSS THE SRN PLAINS IN THE WAKE OF LEAD
SHORTWAVE.  BOUNDARY LAYER MOISTURE SHOULD BE OF HIGH QUALITY ACROSS
THE WARM SECTOR WITH  UPPER 60S/LOWER 70S EXPECTED ACROSS THE SERN
HALF OF THE SLIGHT RISK AREA.  CONVECTIVE MODE/INITIATION WILL BE
SOMEWHAT COMPLEX THROUGH THE PERIOD WITH WEAKENING LOW LEVEL WARM
ADVECTION EXPECTED TO MAINTAIN THUNDERSTORM POTENTIAL FROM PORTIONS
OF AR INTO IL THROUGH MUCH OF THE DAYLIGHT HOURS.  SHEAR PROFILES
WILL SUPPORT STORM ROTATION AND THERE APPEARS TO BE A THREAT FOR
SUPERCELLS...HOWEVER WEAKENING LLJ THROUGH LATE AFTERNOON MAY LIMIT
SEVERE POTENTIAL THROUGH PEAK HEATING.

LATER IN THE EVENING...LLJ SHOULD BEGIN TO INCREASE ACROSS THE SRN
PLAINS IN RESPONSE TO UPSTREAM SPEED MAX AND SFC WARM FRONT SHOULD
LIFT NWD ACROSS ERN OK INTO SERN KS/SWRN MO.  THIS SHARPENING
BAROCLINIC ZONE WILL MOST LIKELY BE THE FOCUS FOR ROBUST SEVERE
THUNDERSTORM DEVELOPMENT DURING THE OVERNIGHT HOURS.  SHEAR PROFILES
WILL BECOME INCREASINGLY FAVORABLE FOR SUPERCELLS...AND WITH SFC DEW
POINTS EXPECTED TO RISE INTO THE LOWER 70S IT APPEARS THE TORNADO
THREAT MAY ACTUALLY INCREASE AS WELL.  WILL MONITOR THIS REGION FOR
A POSSIBLE UPGRADE IN LATER OUTLOOKS.

..DARROW.. 09/21/2006