774 FXUS63 KFSD 101750 AFDFSD AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SIOUX FALLS SD 1150 AM CST WED DEC 10 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 418 AM CST WED DEC 10 2014 COMPLICATED FORECAST AGAIN TODAY AS SMATTERING OF CLOUDS ACROSS THE REGION WHICH WILL IMPACT POTENTIAL WARMING. CURRENTLY...WARM FRONT IS ACROSS THE FAR WESTERN EDGE OF SOUTH DAKOTA...AND A LARGE PART OF THE WARM AIR WILL REMAIN BOTTLED UP WEST OF THE FORECAST AREA TODAY. STRATUS ACROSS SOUTHWEST MINNESOTA EARLY THIS MORNING IS EXPECTED TO RETREAT TO THE NORTHEAST THROUGH THE MORNING TODAY...HOWEVER...AM ALSO CONCERNED ABOUT AREA OF CLOUDS EXPANDING ACROSS EASTERN NEBRASKA. SOUTHERLY FLOW IN THE LOW LEVELS SUGGESTS THAT THIS AREA OF CLOUD COVER WILL LIFT NORTHWARD THROUGH THE DAY IMPACTING ANY POTENTI9AL WARMING ALONG AND EAST OF I-29. SHORT TERM HI-RES MODELS SHOW CLOUD COVER BREAKING APART THIS AFTERNOON....BUT AM NOT COMPLETELY CONVINCED THIS WILL OCCUR...SO HAVE SKY COVER TRENDING TOWARDS A PARTLY CLOUDY SKY THROUGHOUT THE DAY. WITH SKY COVER CONCERNS...HAVE CONTINUED THE TREND DOWNWARD...ESPECIALLY ACROSS THE EAST. MODELS SUGGEST THERE WILL BE A RESURGENCE OF LOW CLOUDS ACROSS THE EASTERN HALF OF THE FORECAST AREA TONIGHT. WITH CLOUDS ACROSS THE AREA...KEPT FORECAST LOWS N THE EAST WARMER THAN IN THE WEST...WITH LOWS IN THE 20S. GIVEN THE STRATUS WILL BE AROUND...AM NOT EXPECTING DENSE FOG TO DEVELOP OVERNIGHT...BUT COULD BE SOME 4-6 SM VISIBILITIES FLOATING AROUND. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 418 AM CST WED DEC 10 2014 CONTINUED CONCERN FOR THE LATER HALF OF THE WEEK WILL BE THE IMPACT OF STRATUS ON THE UNSEASONABLY WARM TEMPERATURES. LARGE SCALE UPPER RIDGING OVER THE WESTERN PLAINS CONTINUES TO SLOWLY SHIFT EASTWARD DURING THIS PERIOD. MID LEVEL TEMPERATURES SOAR THURSDAY AND THURSDAY NIGHT...WITH 850MB TEMPS WELL INTO THE LOW TO MID TEENS CELSIUS. WITH LOW LEVEL SOUTH TO SOUTHWEST WINDS...MOISTURE BELOW THIS TEMPERATURE INVERSION WILL INCREASE...BUT IT LOOKS LIKE THE BEST POTENTIAL FOR PROLONGED STRATUS WILL BE ACROSS OUR SOUTHEASTERN THIRD OF THE FORECAST AREA - PRIMARILY NORTHWEST IOWA AND SOUTHWEST MINNESOTA. THIS LAYER LOOKS TO BE EXTREMELY SHALLOW WITH EXTREMELY DRY AIR ABOVE...WHICH SHOULD PREVENT ANY DRIZZLE DEVELOPMENT. IT ALSO SHOULD ALLOW FOR SOME DISSIPATION DURING THE AFTERNOON HOURS ON THURSDAY FOLLOWED BY A SLIGHT INCREASE THURSDAY NIGHT. HIGHS WILL BE IN THE 40S TO MID 50S THURSDAY AND WARM FURTHER INTO THE MID 40S TO LOWER 60S ON FRIDAY. WARMEST TEMPERATURES WILL BE IN SOUTH CENTRAL SD WHERE SUNSHINE IS MOST LIKELY TO BE ABUNDANT. A STRONGER SURGE OF MOISTURE BUILDS BACK INTO THE AREA LATER FRIDAY AFTERNOON INTO FRIDAY NIGHT. WITH A SLIGHTLY MORE SUBSTANTIAL CLOUD DECK...SOME PATCHY FOG AND DRIZZLE MAY DEVELOP ACROSS OUR EASTERN HALF LATE FRIDAY NIGHT AND PERSIST THROUGH MUCH OF SATURDAY AS THE CLOUD COVER INCREASES TO BLANKET MUCH OF THE FORECAST AREA. WILL CONTINUE WITH SOME LIGHT RAIN CHANCES EXPANDING ACROSS THE FORECAST AREA SATURDAY NIGHT AND SUNDAY WITH A SHORTWAVE LIFTING INTO THE FORECAST AREA DURING THIS PERIOD. HIGHS ON SATURDAY WILL BE MILD IN THE 50S DESPITE THE INCREASED CLOUD COVERAGE. ALL MODELS BEGIN TO PAINT A DEEP CUT OFF LOW EMERGING FROM THE ROCKIES INTO THE CENTRAL AND SOUTHERN PLAINS ON SUNDAY. MODELS SHOW SOME PRETTY SIGNIFICANT DIFFERENCES IN THE IMPACT OF THIS SYSTEM FOR OUR FORECAST AREA. WHILE THE GFS AND GEM TRACK THE STACKED LOW CENTER NEAR THE KANSAS AND OKLAHOMA BORDER...THE ECMWF HAS COME IN FURTHER NORTH CLOSER TO THE NEBRASKA BORDER. AS A RESULT...THERE ARE SOME MAJOR DIFFERENCES IN WHERE THE THERMAL BOUNDARY WILL SET UP SUNDAY NIGHT AND MONDAY. THE GEM HAS VERY LITTLE IMPACT ON OUR FORECAST AREA...WHILE THE GFS BRINGS SOME PRECIPITATION IN THE MISSOURI VALLEY AND NORTHWEST IOWA. THE ECMWF HOWEVER BRINGS AS MUCH AS 1" OF QPF INTO THE HEART OF OUR FORECAST AREA. WITH COOLER AIR RETURNING TO THE FORECAST AREA...MUCH OF THIS PRECIPITATION COULD BE SNOWFALL OR RAIN TURNING TO SNOWFALL. STILL...SO MUCH UNCERTAINTY DURING THE TIME SO WILL LEAVE ONLY CHANCE POPS WHICH ARE HIGHEST IN NORTHWEST IOWA. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 1147 AM CST WED DEC 10 2014 WENT MORE PESSIMISTIC AND TOOK FSD AND SUX INTO THE IFR CATEGORY THROUGH TOMORROW MORNING. WITH AN INCREASING INVERSION SEEMS LIKE IT WILL BE DIFFICULT TO SCOUR OUT CLOUD COVER ONCE IT MOVES IN. SOME QUESTION HOW FAR WEST IT WILL PUSH...BUT MAY ALSO NEED TO BECOME MORE PESSIMISTIC WITH KHON AS WELL. CEILINGS WILL BE THE MAIN CONCERN BUT MVFR FOG ALSO LIKELY OVERNIGHT INTO THURSDAY MORNING. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ SHORT TERM... LONG TERM... AVIATION...08