829 
FXUS63 KFSD 241311
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
811 AM CDT THU OCT 24 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 350 AM CDT THU OCT 24 2013

THE BACKSIDE OF A TROUGH OF LOW PRESSURE TO THE EAST WILL SLOWLY 
WORK EAST OF THE AREA TODAY. SOME MID LEVEL CLOUD COVER SHOULD 
CONTINUE TO FALL APART AS SOUNDINGS SUGGEST THE DEPTH OF THE 
MOISTURE WITHIN THIS CLOUD DECK IS PRETTY THIN. THIS SHOULD ALLOW 
FOR A DECENT AMOUNT OF SUNSHINE...WITH SOUTHWEST MINNESOTA THE ONLY 
AREA THAT COULD SEE SOME STUBBORN PARTLY CLOUDY TO MOSTLY CLOUDY 
CONDITIONS. HIGHS SHOULD MAINLY BE IN THE MID TO UPPER 40S. 

AS THE TROUGH EXITS TONIGHT WARM ADVECTION SETS UP BUT A SIGNIFICANT 
LACK OF MOISTURE WILL NOT SUPPORT ANY PRECIPITATION. WITH WINDS 
TURNING TO THE SOUTH AND SOUTHWEST OVERNIGHT LOW TEMPERATURES SHOULD 
FOLLOW A BIT OF A NON DIURNAL PATTERN SO WILL HAVE 12Z FRIDAY 
TEMPERATURES IN MOST LOCATIONS ABOUT 3 TO 5 DEGREES WARMER THAN 
EXPECTED LOWS...WHICH WILL BE FROM THE UPPER 20S TO LOWER 30S.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 350 AM CDT THU OCT 24 2013

DRY WEATHER WILL PREVAIL FRIDAY INTO THE WEEKEND. WE WILL SEE DECENT 
WARM AIR ADVECTION AHEAD OF AN APPROACHING COLD FRONT ON 
FRIDAY...SETTING UP A WARM DAY ACROSS THE REGION. WENT AHEAD AND 
CONTINUED THE TREND OF BUMPING UP HIGHS A FEW DEGREES. LOOKING FOR 
50S EAST OF THE JAMES RIVER...AND LOW TO MID 60S TO THE WEST. WITH 
MOSTLY SUNNY SKIES...THE ONLY THING PREVENTING A PERFECT DAY WILL BE 
A BLUSTERY SOUTHWEST WIND GUSTING 20 TO 35 MPH...STRONGEST OVER 
SOUTHWEST MINNESOTA. THE COLD FRONT WILL MOVE THROUGH ON FRIDAY 
NIGHT...ALTHOUGH WITH A LACK OF MOISTURE THIS WILL BE A DRY 
PASSAGE...PROBABLY WITHOUT EVEN CLOUD COVER. COOLER CONDITIONS CAN BE 
EXPECTED ON SATURDAY WITH HIGHS RANGING FROM THE MID 40S SOUTHWEST 
MINNESOTA TO LOW 50S ALONG THE MISSOURI RIVER. MAY SEE SOME 
AFTERNOON CU DEVELOP IN THE WELL MIXED BOUNDARY LAYER...WITH 
GREATEST COVERAGE IN THE DEEPER COLD AIR OVER SOUTHWEST 
MINNESOTA...BUT STILL SHOULD BE PARTLY TO MOSTLY SUNNY. NOT THE 
STRONGEST WINDS BEHIND THE FRONT...BUT ENOUGH WINDS ALOFT TO SUPPORT 
A 10 TO 20 MPH NORTHWESTERLY SURFACE BREEZE. WARM AIR ADVECTION 
INCREASES AGAIN ON SUNDAY AHEAD OF A STRONG WAVE DIVING SOUTH ACROSS 
WESTERN CANADA. THUS WE WILL SEE HIGHS REBOUND BACK INTO THE 50S TO 
AROUND 60 UNDER CONTINUED MOSTLY SUNNY SKIES AND RELATIVELY LIGHT 
SOUTHERLY WINDS AROUND 10 MPH.

FORECAST BECOMES MORE COMPLICATED EARLY TO MID NEXT WEEK. A LOT OF 
ENERGY DIVING SOUTH OUT OF WESTERN CANADA INTO THE WESTERN PORTION 
OF THE COUNTRY. AND AS CAN BE EXPECTED WITH THIS MUCH 
ENERGY...MODELS ARE HAVING A TOUGH TIME ON THE EXPECTED EVOLUTION. 
CURRENT BEST GUESS SUGGESTS COLD FRONT WILL MOVE THROUGH SUNDAY 
NIGHT...ALTHOUGH MODELS DISAGREE ON HOW FAR SOUTH THIS GETS. SO IN 
GENERAL LOOKS LIKE MONDAY WILL BE COOLER...BUT EXACTLY HOW COLD WILL 
DEPEND ON THE SOUTHWARD PROGRESSION OF THE FRONT...WITH THE ECMWF 
THE COLDEST SOLUTION AND THE GFS THE WARMEST. AT THIS POINT LOOKS 
LIKE THE UPPER LOW WILL TRY TO CUTOFF SOMEWHERE WEST OF THE ROCKIES. 
A PIECE OF THIS ENERGY MAY EJECT EAST...WHICH COMBINED WITH 
INCREASING ISENTROPIC LIFT AHEAD OF THE DIGGING TROUGH...SUGGEST A 
PERIOD OF PRECIPITATION MONDAY NIGHT INTO TUESDAY WILL BE POSSIBLE. 
PRECIPITATION TYPE WILL AGAIN BE DEPENDENT ON THE SOUTHWARD FRONTAL 
PROGRESSION...AND THUS IS UNCERTAIN. FOR NOW MAINLY JUST WENT WITH 
RAIN AND SNOW MIX...WITH NO REAL PREFERENCE IN ANY ONE SOLUTION AT 
THIS TIME. THE ONLY THING CERTAIN IS THAT THE PROBABILITY OF SEEING 
SNOW INCREASES THE FURTHER NORTH YOU GET.

MEANWHILE THE MAIN UPPER LOW SHOULD NOT STAY CUTOFF FOR LONG AS IT 
GETS FORCED BACK INTO THE WESTERLY FLOW. AS IT MOVES ACROSS THE 
CENTRAL PLAINS...ANOTHER ROUND OF PRECIPITATION IS LIKELY SOMETIME 
WEDNESDAY INTO THURSDAY. BUT EXACTLY WHERE IN THE PLAINS AND WHEN IS 
HIGHLY UNCERTAIN. ALSO UNCLEAR IS WHETHER THE LOW KEEPS ITS NORTHERN 
STREAM COLD AIR CONNECTION...WITH THE LATEST EC SUGGESTING IT DOES 
NOT. SO THE BEST THING THAT CAN BE SAID IS THAT THE MID WEEK 
FORECAST REMAINS HIGHLY UNCERTAIN WITH REGARDS TO PRECIPITATION 
CHANCE AND PRECIPITATION TYPE OVER OUR CWA. AND WITH SO MANY FACTORS 
COMING INTO PLAY IT WILL LIKELY REMAIN UNCERTAIN FOR DAYS TO 
COME...SO THE BEST THING TO DO IS JUST WATCH MODEL TRENDS AND TRY TO 
SLOWLY NARROW IN ON A MOST LIKELY SCENARIO.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 811 AM CDT THU OCT 24 2013

VFR EXPECTED THROUGH 25/12Z. A FEW CEILINGS 3-6K FEET NORTHEAST
PART OF THE FORECAST AREA THROUGH 25/00Z...NORTHEAST OF FSD.

&&

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

$$

SHORT TERM...08
LONG TERM...CHENARD
AVIATION...08