000 
FXUS63 KFSD 020057
AFDFSD

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA 
NATIONAL WEATHER SERVICE SIOUX FALLS SD
800 PM CDT THU SEP 1 2005

.DISCUSSION...
CLEAR AND COOL NIGHT EXPECTED FOR THE CWA.  TEMPERATURES IN A FREE 
FALL FOR THE NEXT COUPLE OF HOURS AS AREA QUICKLY DECOUPLES WITH 
SUNSET.  HAVE INCREASED RATE OF TEMP FALL THIS EVENING IN GRIDS AND 
ALSO DROPPED WINDS TO LIGHT AND VARIABLE EVERYWHERE BUT IN SW MN.  
ALSO DECREASED SKY COVER ACROSS THE REGION.  HAVE LOWERED MIN TEMPS 
A FEW DEGREES IN THE SW CWA AS SFC RIDGE CURRENTLY OVER THE AREA AND 
PAST EVENTS HAVE SHOWN WINDS HAVE DIFFICULTY INCREASING ONCE THEY 
HAVE DECOUPLED...ESP IN VALLEY LOCATIONS.  OTHERWISE FCST LOOKS GOOD.
NEW ZFP AND PFM OUT BY 0130 UTC.

&&

.PREV DISCUSSION...
WARM AND DRY DAY ACROSS THE CWA WITH MOST LOCATIONS TOPPING OUT IN 
THE LOWER AND MID 80S...WITH DEW POINTS CRASHING INTO THE UPPER 30S 
TO LOWER 40S. OTHERWISE...SHORT TERM WEATHER CONCERNS ARE FEW. HAVE 
ADDED A CHANCE FOR ELEVATED THUNDERSTORMS ON FRIDAY NIGHT...SHIFTING 
FROM SOUTHWEST TO NORTHEAST. DECENT 850-800MB MOISTURE CONVERGENCE 
ALONG WITH 800MB LIS OF -4 TO -8 AND A STOUT GRADIENT BETWEEN 
STABLE AIR SHIFTING EAST AND UNSTABLE AIR SHIFTING NORTHEAST. RIGHT 
NOW SEVERE THREAT NOT A MAJOR CONCERN...BUT -14 TO -15 AT 500MB AND 
INCREASING MID LEVEL INSTABILITY MAY BE ENOUGH TO CONJURE UP SOME 
ELEVATED HAILERS.

AS FOR TEMPERATURES...TONIGHT COULD GET PRETTY DARN CHILLY...WITH 
NORTHERN TIER POSSIBLY CREEPING INTO THE LOWER 40S IN SOME OF THE 
LOW SPOTS. WOULD EXPECT LOWS FROM ABOUT LOWER 50S SOUTHWEST TO MID 
40S EAST. FRIDAY SHOULD PROVE TO BE THE BEST DAY OF THE UPCOMING 
WEEK WITH LIGHT WINDS...NOT MUCH IN THE WAY OF CLOUDS AND MILD 
TEMPS. AIMING FOR DECREASED MIXING WITH HIGHS FROM THE MID 70S IN SW 
MN TO THE MID 80S IN SOUTH CENTRAL SD. FRIDAY NIGHT SHOULD SEE SOME 
RESIDUAL CHILLY EFFECTS ALONG AND EAST OF THE BUFFALO RIDGE...AND 
WILL LOWER LOWS BELOW GUIDANCE IN THESE PARTS. LOWS MAY ALSO OCCUR A 
LITTLE EARLIER THAN NORMAL...WITH INCREASING CLOUDS AND A CHANCE FOR 
PRECIP. WILL GO LOWER 50S FAR EAST TO LOWER 60S TOWARDS THE MO 
RIVER. SATURDAY WILL TRY TO WARM UP...BUT YESTERDAYS TRENDS OF 
SHIFTING WARM FRONT MAINLY NORTH OF THE CWA HAS BACKED TO LEAVING IT 
NEAR I90 BY AFTERNOON. SO...WILL TREND TEMPERATURES BACK A FEW 
DEGREES.    

IN THE LATTER PERIODS...MODELS SLOWING DOWN PROGRESSION OF 
FRONT...WHICH WAS BUILT INTO FORECAST A BIT YESTERDAY...AND WILL 
CONTINUE THIS TREND. WILL NOT GO TOO HOT AHEAD OF THIS FRONT ON SUN 
AND MON AS COOL HIGH PRESSURE SOUTHEAST OF AREA STILL HAVING SOME 
EFFECT ON TEMPS...ESPECIALLY THE SOUTHEAST TWO THIRDS. ALL MODELS 
EXCEPT THE 12Z GFS BRINGING IN SOME DECENT COOLING BEHIND FRONT ON 
WED-THU. SO...WOULD NORMALLY AIM BELOW GUIDANCE IN THIS CASE BUT 
SINCE LATEST GFS NOT VERY COOL BEHIND BOUNDARY AND GFS ENS MEAN DATA 
ALSO INDICATING MAXES ABOVE MEX GUIDANCE BOTH DAYS...WILL NOT STRAY 
TOO FAR FROM GUIDANCE UNTIL CONFIDENCE A LITTLE HIGHER. WILL 
CONTINUE CHANCE FOR PRECIPITATION MONDAY NIGHT INTO TUESDAY WITH 30 
AND 40 POPS. NOTHING NEW THAT REALLY SUGGESTS DECREASING OR 
INCREASING POPS...ALTHOUGH MAIN UPPER WAVE DOES SHOW SOME 
INDICATIONS THAT IT MAY END UP FARTHER NORTH THAN SOUTH...WHICH 
WOULD DECREASE OUR CHANCES IF THESE TRENDS CONTINUE.  

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.

&&

$$

SCHUMACHER/08