000 
FXUS63 KFSD 152034
AFDFSD

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA 
NATIONAL WEATHER SERVICE SIOUX FALLS SD
230 PM CST SAT JAN 15 2005

.DISCUSSION...
LARGE ARCTIC HIGH EXTENDED FROM MONTANA TO IOWA AND WILL MOVE EAST 
TONIGHT THRU SUNDAY. THIS WILL KEEP THE COLD AIR OVER THE AREA 
HOWEVER WINDS ARE EXPECTED TO BE LESS THEN 10 MPH FOR THE MOST PART 
SO NO HEADLINES FOR WIND CHILLS. WEAK WAVE WILL KEEP CLOUDS OVER 
SOUTHERN AREAS THIS EVENING BUT THESE WILL THEN DECREASE LATER 
TONIGHT FOR MOSTLY CLEAR SKIES AFTER MIDNIGHT AND SUNDAY. TEMPS 
TONIGHT SHOULD AGAIN FALL TO 10 BELOW TO 20 BELOW. NO BIG CHANGE TO 
AIR MASS SO HIGHS ON SUNDAY SHOULD BE SIMILAR TO TODAY. SUNDAY NIGHT 
WINDS SHIFT TO LIGHT SE WITH AN INCREASE IN CLOUDS. TEMPS STILL 
DROPPING TO BELOW ZERO BUT NOT AS FAR. AFTER MIDNIGHT WITH MORE 
MOISTURE AND A LITTLE LIFT WILL HAVE SLIGHT CHANCE OF LIGHT SNOW IN 
WEST. ON MONDAY WEAK WAVE WILL MOVE OVER AREA WITH A CHANCE OF 
LIGHT SNOW. NOT A LOT OF MOISTURE SO SNOW AMOUNTS SHOULD BE LESS 
THAN AN INCH. TEMPS WILL ALSO BE WARMING ON MONDAY BUT WITH EAST TO 
SOUTHEAST WINDS THEY STILL WILL BE BELOW NORMAL. CHANCE OF LIGHT 
SNOW MOVES EAST MONDAY EVENING WITH WAVE BUT SOUTH WINDS AND CLOUDS 
SHOULD HOLD TEMPS ABOVE ZERO. WINDS SHIFT MORE TO SOUTHWEST ON 
TUESDAY AS SURFACE LOW OVER S CNTRL CANADA MOVES INTO GREAT LAKE 
REGION.  THIS SHOULD WARM TEMPS TO NORMAL OR A LITTLE ABOVE AS IT 
STAYS DRY. WINDS DO SHIFT TO NW TUESDAY NIGHT NIGHT BUT NOT BIG PUSH 
OF COLDER AIR.   

&&

IN THE EXTENDED FORECAST...THE MAIN CONCERN IS TOWARD NEXT WEEKEND.  
ALL MODELS...ECMWF...GFS...ENSEMBLES...CANADIAN...ADVERTISE AND 
SHORT-WAVE MOVING ACROSS THE NRN PLAINS IN THE WNW FLOW ALOFT THU 
NIGHT AND FRIDAY.  WITH ENSEMBLES ADVERTISING OVER 50 PERCENT CHC OF 
GREATER THAN TENTH OF INCH...HAVE SOME CONFIDENCE THAT PRECIPITATION 
WILL OCCUR AND HAVE ADDED POPS THU NIGHT AND FRIDAY TO THE ERN TWO 
THIRDS OF THE CWA. WITH MOST MODELS FOCUSED EAST OF I29...HAVE 
HIGHEST POPS IN SW MN/NW IA WITH NO POPS IN SOUTH CENTRAL SD WHERE 
THE SURFACE LOW WILL GO.  AS FOR TYPE...HAVE GONE ALL SNOW.  MODELS 
SHOW WHERE SNOW BREAKS OUT...850 MB TEMPS ARE BELOW ZERO.  
THEREFORE...EXPECT THAT PLACES MODEL IS DEPICTING ABOVE 0C...WILL 
FALL BELOW 0C WITH EVAPORATIVE COOLING IF SNOW DOES DEVELOP.  

AS FOR TEMPS...HAVE LOWERED TEMPS A FEW DEGREES IN MOST PERIODS.  
BACKDOOR COLD FRONT EXPECTED TO MOVE THROUGH WITH A VERY TIGHT 
THERMAL GRADIENT.  THIS WILL LIKELY LEAD TO ONE OR TWO DAYS WITH A 
15 TO 25 DEGREE DIFFERENCE IN TEMPS FROM SW MN TO SOUTH CENTRAL SD.  
BECAUSE EVEN A SMALL ERROR IN FRONTAL POSITION COULD LEAD TO LARGE 
CHANGE IN TEMPS...HAVE NOT GONE THAT EXTREME WITH TEMP 
GRADIENT...BUT DO HAVE TEMPS ABOVE FREEZING NEAR K9V9 WHILE AROUND 
20 AROUND KMML WITH ENE FLOW.  SHOULD ALSO BE A FAIRLY CLOUDY PERIOD 
THROUGH THE CWA FOR MUCH OF THE PERIOD AS BAROCLINIC ZONE IS NEARBY 
MOST DAYS.  THEREFORE HAVE RESTRICTED DIURNAL RANGE TO 10 TO 15 
DEGREES IN MOST PLACES.

&&

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

&&

$$

WB/SCHUMACHER