[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 220600
SWODY2
SPC AC 220559

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CDT FRI SEP 22 2006

VALID 231200Z - 241200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MID-MS
VALLEY...OH VALLEY...GREAT LAKES...OZARKS AND SRN PLAINS...

...MID-MS VALLEY/OZARKS/OH VALLEY/GREAT LAKES...
AN IMPRESSIVE UPPER-LOW SHOULD BE IN THE NRN PLAINS SATURDAY MORNING
WITH THE LOW FORECAST TO EJECT NEWD ACROSS THE UPPER MIDWEST
SATURDAY AFTERNOON. SEVERAL STRONG TO POSSIBLY SEVERE MESOSCALE
CONVECTIVE SYSTEMS SHOULD BE ONGOING AT THE BEGINNING OF THE PERIOD
ALONG AND AHEAD OF A FRONTAL BOUNDARY EXTENDING SSWWD FROM A SFC LOW
IN THE UPPER MIDWEST ACROSS IA INTO WRN MO AND ERN OK. SFC DEWPOINTS
AHEAD OF THE BOUNDARY SHOULD BE IN THE UPPER 60S TO LOWER 70S F
WHICH MAY RESULT IN WIDESPREAD MODERATE INSTABILITY ACROSS THE WARM
SECTOR BY SATURDAY AFTERNOON. AS A RESULT...THUNDERSTORM COVERAGE
SHOULD INCREASE ALONG AND AHEAD OF THE FRONT WITH SQUALL-LINE
FORMATION LIKELY BY LATE AFTERNOON INTO THE EVENING ACROSS THE OH
VALLEY...MID-MS VALLEY AND OZARKS.

FORECAST SOUNDINGS SATURDAY AFTERNOON AND EVENING ACROSS THE REGION
SHOW 0-6 KM SHEAR VALUES IN THE 50 TO 70 KT RANGE SUGGESTING SHEAR
PROFILES WILL BE FAVORABLE FOR SEVERE STORMS. THE LARGE NUMBER OF
STORMS FORECAST IN THIS FAVORABLE WIND ENVIRONMENT SHOULD RESULT IN
A MIXTURE OF STORM MODE WITH SUPERCELLS...BOW ECHOES AND SEVERE
MULTICELLS ALL LIKELY. SUPERCELLS WILL BE MOST LIKELY IN AREAS OF
ENHANCED INSTABILITY WHERE STORMS REMAIN DISCRETE. SUPERCELLS WILL
ALSO BE POSSIBLE OUT AHEAD OF THE SQUALL-LINE OR ON THE SRN END OF
CONVECTIVE LINES. SUPERCELLS AND BOW ECHOES WILL ALSO LIKELY BE
EMBEDDED IN THE SQUALL-LINE. SEVERAL TORNADOES MAY OCCUR WITH
SUPERCELLS AND/OR WITH THE STRONGER BOW ECHOES. THE TORNADO THREAT
SHOULD BE THE GREATEST IN THE OH VALLEY ON THE NORTHWEST SIDE OF A
60 KT LOW-LEVEL JET WHERE LOW-LEVEL SHEAR SHOULD BE ENHANCED. THIS
AREA IS ALSO FORECAST TO HAVE THE GREATEST LARGE-SCALE ASCENT
ASSOCIATED WITH THE EJECTING UPPER-LOW. WIND DAMAGE AND LARGE HAIL
WILL ALSO BE LIKELY WITH THE SUPERCELLS AND STRONGER BOWING
SEGMENTS. THE LARGE NUMBER OF STORMS AND WIDESPREAD CLOUD COVER MAY
INHIBIT DESTABILIZATION OVER SOME AREAS AND THE EXTENT OF
DESTABILIZATION STILL REMAINS UNCERTAIN. IF IT APPEARS MODERATE
INSTABILITY WILL BECOME WIDESPREAD WITH AN INTENSE SQUALL-LINE
AND/OR A LARGE NUMBER OF RELATIVELY DISCRETE STORMS...THEN AN
UPGRADE TO MODERATE RISK MAY BECOME NECESSARY IN LATER OUTLOOKS.

....SRN PLAINS...
WEST TO SOUTHWEST FLOW ALOFT WILL IN BE IN PLACE ACROSS THE SRN
PLAINS AHEAD OF AN APPROACHING UPPER-LEVEL TROUGH. MODEL FORECASTS
DISAGREE ON WHETHER CONVECTIVE CLUSTERS WILL BE ONGOING AT THE
BEGINNING OF THE PERIOD AHEAD OF A COLD FRONT LOCATED FROM ERN OK
INTO CNTRL TX. MODEL FORECASTS DO AGREE WITH DEVELOPING MODERATE
INSTABILITY ACROSS A WIDESPREAD AREA AHEAD OF THE FRONT IN CNTRL AND
ERN TX. THIS SHOULD RESULT IN THUNDERSTORM INITIATION JUST ALONG AND
JUST AHEAD OF THE BOUNDARY WITH THE DEVELOPMENT OF A SQUALL-LINE
AND/OR A BROKEN LINE SEGMENT GRADUALLY ORGANIZING DURING THE
AFTERNOON AND EARLY EVENING.

FORECAST SOUNDINGS LATE SATURDAY AFTERNOON ACROSS THE REGION SHOW
0-6 KM SHEAR VALUES IN THE 35 TO 45 KT RANGE SUGGESTING SHEAR WILL
BE ADEQUATE FOR ISOLATED SUPERCELLS AND SEVERE MULTICELLS ALONG AND
AHEAD OF THE FRONT. ALTHOUGH LOW-LEVEL FLOW IS FORECAST TO BE
STRONGER NORTHEAST OF THE REGION...AN ISOLATED TORNADO THREAT MAY
STILL EXIST WITH THE STRONGER SUPERCELLS DURING THE LATE AFTERNOON
AND EARLY EVENING. ISOLATED WIND DAMAGE AND LARGE HAIL WILL BE
POSSIBLE WITH SUPERCELLS AND BOWING SEGMENTS ALONG THE CONVECTIVE
LINE DURING THE AFTERNOON AND EVENING.

..BROYLES.. 09/22/2006