[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 220549
SWODY1
SPC AC 220548

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1248 AM CDT FRI SEP 22 2006

VALID 221200Z - 231200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER AR...SRN/ERN MO...AND
CENTRAL/SRN IL...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK OVER
THE MIDDLE MS AND LOWER OH VALLEYS SWWD INTO NERN TX...

...SYNOPSIS...
HIGH AMPLITUDE ENERGETIC FLOW PATTERN IS FORECAST TO CONTINUE
THROUGH THE PERIOD AS CENTRAL PLAINS OCCLUDED UPPER LOW LIFTS NWD
TOWARD SD AND BEGINS TO WEAKEN...AS UPSTREAM SHORT WAVE TROUGH OVER
THE NRN INTERMOUNTAIN REGION DIGS SEWD INTO THE GREAT BASIN.  THIS
WILL RESULT IN A STRONG MID/UPPER LEVEL JET STREAM BECOMING
ESTABLISHED FROM THE NRN PARTS OF AZ/NM ACROSS KS/OK AND THE MIDDLE
MS VALLEY TODAY.

AT THE SURFACE...COMPLEX PATTERN IS FORECAST TO EVOLVE AS OCCLUDED
LOW LIFTS NWD TOWARD ERN SD/SWRN MN...WITH A COLD FRONT ARCING SWD
FROM THE LOW INTO THE LOWER MO RIVER VALLEY THEN SWWD INTO THE SRN
HIGH PLAINS.  THE COLD FRONT IS FORECAST TO MOVE SEWD ACROSS THE SRN
PLAINS REGION DURING THE NIGHT.  IN ADVANCE OF THE COLD FRONT...A
DRY LINE IS EXPECTED TO BE LOCATED FROM ERN KS/WRN MO SWD ACROSS ERN
OK INTO CENTRAL TX.

...IL/MO/AR AREA...
...SIGNFICANT SEVERE THREAT EXPECTED TODAY...
STRONG NOCTURNAL CONVECTION OVER PARTS OF MO AND AR IS EXPECTED TO
MOVE EWD/NEWD DURING THE EARLY MORNING HOURS AND POSSIBLY CONTINUE
INTO THE MS VALLEY PRIOR TO 18Z.  THE MORNING ACTIVITY IN THE MIDDLE
MS VALLEY WILL LIKELY REMAIN BELOW SEVERE LEVELS AS MOISTURE AND
INSTABILITY WILL BE MARGINAL...ALTHOUGH THE STORMS MOVING INTO THE
MID SOUTH REGION MAY HAVE POTENTIAL TO PRODUCE MARGINALLY SEVERE
HAIL.

LOW LEVEL MOISTURE IS EXPECTED TO INCREASE NWD IN THE WAKE OF THE
MORNING CONVECTION.  SURFACE DEW POINTS OF 65-70F ARE CURRENTLY OVER
ERN OK INTO SRN/ERN TX AND LA AND MODEL GUIDANCE INDICATES THAT
MOISTURE WILL SURGE NWD TOWARD THE MIDDLE MS VALLEY DURING THE LATE
MORNING AND AFTERNOON HOURS.  ALTHOUGH RESIDUAL CLOUDS AND
OCCASIONAL CONVECTION WILL INHIBIT DIURNAL HEATING ACROSS PARTS OF
THIS REGION...STRONGER HEATING IS LIKELY WHERE BREAKS IN THE CLOUD
COVER DEVELOP...AND ALONG THE WRN PORTIONS OF THE LOW LEVEL MOIST
AXIS FROM ERN OK/WRN AR INTO WRN MO/IA.  THIS WILL ENHANCE
DESTABILIZATION WITH MLCAPE RANGING FROM 1500-2000 J/KG OVER AR INTO
SRN MO TO AROUND 1000 J/KG FROM NRN MO INTO CENTRAL IL.

MULTIPLE BANDS OF CONVECTION ARE EXPECTED TO DEVELOP DURING THE
AFTERNOON FROM PARTS OF ERN OK/WRN OK NNEWD INTO MO AND IL WITHIN A
WEAKLY CAPPED ENVIRONMENT.  MODEL FORECAST SOUNDINGS INDICATE WINDS
WILL VEER AND STRENGTHEN WITH HEIGHT AS 40-50 KT SSWLY LOW LEVEL
FLOW VEERS TO WLY/SWLY AT 50-75 KT ACROSS AN EXPANSIVE WARM SECTOR. 
THIS RESULTS IN VERY STRONG DEEP LAYER SHEAR /50-60 KT IN THE LOWEST
6 KM/ INDICATING A LIKELIHOOD FOR PERSISTENT SUPERCELLS TO DEVELOP. 
LOW LEVEL SHEAR WILL ALSO BE VERY STRONG WITH 0-1 KM SRH OF 200-400
M2/S2. GIVEN THE ANTICIPATED LOW LCL HEIGHTS AND POTENTIAL FOR
DEVELOPMENT OF DISCRETE STORMS AND EMBEDDED SUPERCELLS WITHIN SHORT
LINE SEGMENTS...THERE IS A THREAT FOR A FEW STRONG TORNADOES TO
DEVELOP...IN ADDITION TO DAMAGING WIND GUSTS AND LARGE HAIL.  THIS
ACTIVITY WILL SPREAD NEWD THROUGH THE EVENING HOURS ACROSS THE
MIDDLE MS VALLEY INTO THE LOWER OH VALLEY.

..WEISS/GRAMS.. 09/22/2006