[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 242000
SWODY1
SPC AC 241958

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0258 PM CDT THU AUG 24 2006

VALID 242000Z - 251200Z

...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND TONIGHT OVER
PARTS OF NERN SD...SERN ND...CNTRL/SRN MN AND W-CNTRL WI...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE DAKOTAS INTO PARTS OF
THE UPPER GREAT LAKES...

...DAKOTAS INTO THE UPPER GREAT LAKES...

COMPLEX SCENARIO IS EVOLVING TODAY ACROSS THE REGION IN ADVANCE OF
STRONG SHORT WAVE TROUGH TRANSLATING EWD THROUGH WRN/CNTRL ND. 
WATER VAPOR IMAGERY SUGGESTS THAT A LEAD IMPULSE IS CURRENTLY
SHIFTING EWD THROUGH CNTRL/ERN SD WHICH IS LIKELY SUPPORTING THE
ONGOING STORMS FROM FAR NERN SD INTO CNTRL MN. IN THE
LOW-LEVELS...PRIMARY SURFACE LOW APPEARS TO BE W OF MBG WITH
ATTENDANT WARM FRONT EXTENDING SEWD TO NEAR HON AND THEN ACROSS SRN
MN TO NEAR THE WI/IL BORDER. A SECONDARY SURFACE LOW WAS ANALYZED
ALONG THIS BOUNDARY N OR NE OF FSD WITH A TRAILING PRE-FRONTAL
TROUGH STRETCHING SWWD FROM THIS LOW INTO CNTRL NEB. 
MEANWHILE...COLD FRONT /CURRENTLY MASKED BY ADIABATIC DOWNSLOPE
WARMING/ EXTENDED FROM NEAR MOT TO PHP INTO THE NEB PNHDL.

THUS FAR TODAY...PRIMARY SEVERE IN THE FORM OF ELEVATED SUPERCELLS
PRODUCING LARGE /AND AT TIMES SIGNIFICANT/ HAIL HAS PERSISTED FROM
CNTRL MN INTO SRN WI IN ASSOCIATION WITH LOW-LEVEL WAA/ISENTROPIC
ASCENT REGIME N OF WARM FRONT. BOTH 12Z AND 18Z REGIONAL SOUNDINGS
INDICATE THAT INFLOW PARCEL SOURCE REGION OVER THE MID MO VALLEY
INTO SRN MN REMAINS MODERATE TO STRONGLY UNSTABLE WITH MUCAPES OF
2500-4500 J/KG.  STRENGTHENING SWLY LLJ THIS AFTERNOON AND TONIGHT
SHOULD MAINTAIN CLUSTERS OF ELEVATED SUPERCELLS TO THE N OF SURFACE
BOUNDARY WITH VERY LARGE HAIL BEING THE MAIN SEVERE THREAT.

OTHER SURFACE-BASED STORMS WILL BECOME INCREASINGLY LIKELY LATE THIS
AFTERNOON INTO EVENING FROM SERN SD EWD ACROSS SRN MN NEAR AND E OF
TRIPLE POINT ASSOCIATED WITH SECONDARY SURFACE LOW.  MODERATELY
STRONG LOW-LEVEL SHEAR /0-1 KM SRH OF 100-200 M2/S2/ COUPLED WITH
THE MODERATE TO STRONG INSTABILITY AND 40-50 KTS OF EFFECTIVE BULK
SHEAR INDICATE THE POTENTIAL FOR SUPERCELLS CAPABLE OF A FEW
TORNADOES...LARGE HAIL AND DAMAGING WINDS SHOULD STORMS DEVELOP AND
BECOME SUSTAINED.

FARTHER DOWNSTREAM...TSTM COMPLEX OVER SRN WI WILL POSE A DAMAGING
WIND/LARGE HAIL THREAT AS IT CONTINUES SEWD ALONG BAROCLINIC ZONE
ACROSS SERN WI/NERN IL.

MEANWHILE...A LARGE CLUSTER OF TSTMS INCLUDING EMBEDDED SUPERCELLS
CONTINUES TO INCREASE IN COVERAGE AND INTENSITY THIS AFTERNOON OVER
PORTIONS OF WRN AND CNTRL ND...IMMEDIATELY AHEAD OF SHORT WAVE
TROUGH.  VISIBLE SATELLITE IMAGERY AND SURFACE OBSERVATIONS INDICATE
THAT AIR MASS IS RECOVERING AHEAD OF THIS ACTIVITY OVER N-CNTRL SD
INTO S-CNTRL ND WHERE STRONGER DIABATIC HEATING HAS ALLOWED
TEMPERATURES TO WARM INTO THE 80S...SUPPORTING MLCAPES OF 1500-3000
J/KG.  WHILE THERE HAS BEEN SOME TENDENCY FOR STORMS TO EVOLVE INTO
A MORE LINEAR CONFIGURATION...POTENTIAL STILL EXISTS FOR MORE
DISCRETE SUPERCELLS ALONG SRN PORTION OF COMPLEX NEAR SURFACE LOW
AND ATTENDANT WARM FRONT WITH A THREAT OF A FEW TORNADOES AS WELL AS
LARGE HAIL AND DAMAGING WINDS.

THERE IS SOME UNCERTAINTY AS TO HOW FAR S STORMS WILL FORM INTO
CNTRL SD OWING TO CLOSE PROXIMITY OF LEAD SHORT WAVE TROUGH OVER ERN
SD.  LATEST VISIBLE IMAGERY DOES INDICATE DEEPENING CUMULUS ALONG
COLD FRONT SW OF MBG AND SSE PHP.  SHOULD STORMS DEVELOP AND BECOME
SUSTAINED THE COMBINATION OF MODERATE TO STRONG INSTABILITY AND
MODERATELY STRONG VERTICAL SHEAR WILL BE SUPPORTIVE OF SUPERCELLS
AND BOWING STRUCTURES CAPABLE OF LARGE HAIL...DAMAGING WINDS AND
PERHAPS A COUPLE OF TORNADOES.

..MEAD.. 08/24/2006