660 FXUS63 KFSD 272107 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 307 PM CST Sun Jan 27 2019 .SHORT TERM...(This evening through Monday) Issued at 306 PM CST Sun Jan 27 2019 Active weather pattern in place, will bring several impacts to the region through the upcoming week. The main areas of concern will focus on the ongoing warm air advection and mixed precipitation event this afternoon through tonight, followed by a strong arctic cold blast which will bring extreme cold and dangerous wind chills for much of the work week. Strong theta-e advection has overrun the region, with a sharp temperature gradient seen across the northern and central Plains. With temperatures in the 40s in south central SD and central Nebraska, while single digits remain in southwest Minnesota and northeast SD, temperatures remain a tricky forecast. Expect warming to continue spreading northeastward this afternoon into much of the evening with gusty southerly winds in the warm sector of the approaching surface low. Light snowfall continues to fall in the vicinity of the elevated theta-e boundary in northeast and east central SD into southwest Minnesota and northwest Iowa. Light precipitation will become possible across the entire forecast area later this evening, but the bulk of the measurable precipitation will remain north of a Huron to Sioux Falls to Spencer IA line. Still looking at 3 to 6 inches in east central SD, southwest MN, and portions of northwest Iowa where models suggest a band of frontogenesis is expected to set up this evening from 00z through 06z. In light of this, models are showing a bit higher QPF in this area, so did bolster amounts slightly, while portions of northwest Iowa may see slightly less than previously forecast. Northwest Iowa may be more marginal for reaching advisory criteria, but will leave the headline as is, given the strong winds arriving and in the event that the heavier snowfall rates do drift a little further south. Elsewhere, with the warmer temperatures advecting into the area this afternoon and evening, expect much of southeast SD, including the James and Missouri Valleys, to mix with rain or sleet at times, likely becoming primarily rain in south central. Precipitation is expected to become light within this mix, which will keep icing concerns a minimum. With winds flipping to the west then northwest late evening into the early morning hours, colder air will again surge from northwest to southeast, quickly dropping temperatures back into the single digits by daybreak. Any liquid precipitation would change back to snow. If there is something to watch for - with much colder temperatures arriving, we could see some slippery roadways where rain falls and then flash freezes with the cold air arrival. But given that any liquid precip is expected to be quite light, this should be less of a concern. Behind the passing low pressure system, the aforementioned northwest winds will increase to around 25 to 40 mph, with gusts as high as 50 to 60 mph. Strongest winds are expected in the Missouri valley where the high wind warning remains, with a wind advisory elsewhere the winter weather advisory doesn't exist. The winds will of course cause areas of blowing snow and reduced visibility especially while snow is falling. Winds gradually decrease through the day on Monday, however blowing snow will remain a concern in areas with recent snowfall. Snow will come to an end around daybreak, but there may be some lingering flurries in the area with no additional accumulations. Temperatures will continue to fall through the day or remain steady. .LONG TERM...(Monday night through Sunday) Issued at 306 PM CST Sun Jan 27 2019 The main focus in the extended forecast remains the brutally cold airmass settling over much of the central US through the upcoming week. Lows Monday night will reach the single digits below zero for most locations, followed by steady readings during the day on Tuesday as a reinforcing shot of arctic air arrives. The coldest night will be Tuesday night, with lows around -20 to -35 and somewhat breezy northwest winds continuing overnight. This will result in extremely dangerous wind chills of -50 to -65 in the for the northeastern half of the forecast area and solidly within warning criteria elsewhere. Highs on Wednesday will be well below zero for most. The wind chill watch remains in effect for the entire region. Will wait until the ongoing system exits to upgrade to a warning. The good news is that temperatures will be on a warming trend Thursday into the end of the week. && .AVIATION...(For the 18Z TAFS through 18Z Monday afternoon) Issued at 1124 AM CST Sun Jan 27 2019 Conditions will slowly worsen across the region this afternoon, but especially this evening. Initial warm advection snows will lift to the north and east, with the synoptic wave arriving this evening. Some model guidance has trended further south with this wave suggesting snow may impact FSD a bit more than previously expected. Winds will increase after midnight, and gusts up to or exceeding 50 mph may be possible through mid- morning Monday. Periods of blowing snow may be likely after midnight into Monday morning. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...High Wind Warning from midnight tonight to noon CST Monday for SDZ050-057-063-068>071. Wind Advisory from midnight tonight to noon CST Monday for SDZ038-052>054-058>062-064>067. Wind Chill Watch from Tuesday evening through Wednesday morning for SDZ038-050-052>054-057>071. Winter Weather Advisory until noon CST Monday for SDZ039-040. Wind Chill Watch from Tuesday afternoon through late Wednesday night for SDZ039-040-055-056. Winter Weather Advisory from midnight tonight to noon CST Monday for SDZ055-056. MN...Winter Weather Advisory until noon CST Monday for MNZ071-072-080- 081-097. Wind Chill Watch from Tuesday afternoon through late Wednesday night for MNZ071-072-080-081-089-090-097-098. Winter Weather Advisory from midnight tonight to noon CST Monday for MNZ089-090-098. IA...High Wind Warning from midnight tonight to noon CST Monday for IAZ031. Wind Advisory from midnight tonight to noon CST Monday for IAZ012-020>022-032. Wind Chill Watch from Tuesday evening through Wednesday morning for IAZ012-020>022-031-032. Wind Chill Watch from Tuesday afternoon through late Wednesday night for IAZ001>003-013-014. Winter Weather Advisory from midnight tonight to noon CST Monday for IAZ001>003-013-014. NE...High Wind Warning from midnight tonight to noon CST Monday for NEZ013-014. Wind Chill Watch from Tuesday evening through Wednesday morning for NEZ013-014. && $$ SHORT TERM... LONG TERM... AVIATION...Dux