039 FXUS63 KFSD 200831 AFDFSD AREA FORECAST DISCUSSION National Weather Service Sioux Falls SD 331 AM CDT Mon May 20 2019 .SHORT TERM...(Today and Tonight) Issued at 331 AM CDT Mon May 20 2019 Cold high pressure building into the area this morning dropping temperatures back into the 30s in many locations. Frost advisory still in place north of Interstate 90 early this morning but some patchy mid level cloudiness has so far protected the area from a pure radiational temperature fall. Clouds will continue to expand northeast through the day with winds gradually increasing from the east and southeast. This is in response to developing low pressure over southern parts of the High Plains. The energy from this developing low pressure is a little slower to lift northward so have slowed down the development of rainfall. Right now looking like a good chance for I-29 and east to remain dry all day with some light rain possible towards sunset. West of the James River it still looks like rain should develop in the afternoon while also seeing a threat for some light rain this morning. Raised high along and east of the James River with a little less dense cloud cover and a later arrival of rainfall. South central SD may still struggle to get to 50 today. By tonight moisture advection from about 750mb to 650mb will allow for some lighter showers to develop and lift north. These showers will be fighting through some dry air below about 800mb however so not expecting a lot of accumulation before 6z other than south central SD where a couple tenths will be possible. From 6z to 12z tonight the moisture advection lowers in the atmosphere as low pressure lifts north helping to increase the warm and moist advection. Expecting around a quarter of an inch near the Missouri River by 12z Tuesday. .LONG TERM...(Tuesday through Sunday) Issued at 331 AM CDT Mon May 20 2019 Windy, cold and rainy conditions still expected on Tuesday as the upper level low deepens and slowly lifts north across the Western High Plains and into Central Nebraska Tuesday night. east winds will average about 25 to 40 mph on Tuesday with periods of rain through the night. Convection not overly likely but will keep a small chance around northwest Iowa with some minor elevated instability creeping up into eastern Nebraska. Rainfall amounts on Tuesday should be a bit burlier with a half an inch to an inch and a half very possible. Highs Tuesday likely 50 to 55 most spots. As the upper level low wraps northward and remains mostly west of eastern South Dakota on Wednesday, dry air will wrap in aloft and likely bring an end to the rain. Soundings not overly supportive on rain on Wednesday as southerly flow mixes out the low levels and dries out there as well. So, other than the strong southerly winds gusting to 25 to 35 mph Wednesday may turn out to be an ok day. Winds will be strongest in far southeast SD, northeast NE and northwest IA. Highs should range from the lower 60s in central SD where clouds may linger longest to 70 to 75 in northwest IA. Upper level ridging builds into the area Wednesday afternoon into Thursday morning which should keep conditions dry and mild. Lows Wednesday night in the 40s to lower 50s and highs Thursday from the mid 60s in central SD to the mid 70s in northwest IA. There will be an increasing threat for showers and thunderstorms Thursday afternoon and night as another piece of energy cranks up the warm and moist advection. Severe weather will be possible during this time with some very impressive shear possible but right now the cap appears to be a problem below about 900 mb so the directional low level shear will go unused but still strong speed shear aloft and above the cap. Something to watch for. After this ridging tries to build into the area so mostly dry and near to slightly above normal temperatures are expected Friday through Sunday. There are hints of a fast moving upper level wave Saturday night so will have a chance for showers and thunderstorms then. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 1036 PM CDT Sun May 19 2019 MVFR ceilings will continue to thin out during the early night time hours. Could see some patchy fog development around KHON after 10z, lingering into mid morning on Monday. Showers will redevelop by Monday afternoon, and become more expansive by late evening. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...Frost Advisory until 9 AM CDT this morning for SDZ038>040- 052>056. MN...Frost Advisory until 9 AM CDT this morning for MNZ071-072-080- 081-097. IA...NONE. NE...NONE. && $$ SHORT TERM...08 LONG TERM...08 AVIATION...JM