575 FXUS63 KFSD 180457 AAB AFDFSD AREA FORECAST DISCUSSION...UPDATED National Weather Service Sioux Falls SD 1057 PM CST Fri Jan 17 2020 .UPDATE... Issued at 720 PM CST Fri Jan 17 2020 Latest infrared satellite imagery shows dry mid level air pushing off to the east, inducing decreasing winds and an anticipated lull in activity, other than continued freezing drizzle across much of the region. This brief respite will only last a few hours. Satellite imagery shows cold air mid level air starting to enter the James River valley, which will change the precipitation type to dominantly snow later this evening. Will continue to monitor the eastward progression of the approaching Arctic front, currently situated just west of a line from Aberdeen to Winner. Behind the front, strong northwest winds will likely ramp up blizzard conditions rapidly. && .SHORT TERM...(This Evening through Saturday) Issued at 407 PM CST Fri Jan 17 2020 Current radar/satellite images indicating drying in the mid levels, with snowfall beginning to lighten up through the western and southern portions of the CWA. In addition, current obs at KHON, KMHE, and KSUX are reporting -FZRA/UP, so forecast is on track with previous thinking of a dry slot moving up over the area. Am not expecting significant icing as forcing weakens through the afternoon/early evening. Later this evening, an inverted trough begins to work across the region, with snow redeveloping as forcing increases and the midlevels saturate once again. Not expecting snowfall as heavy as today though, with additional amounts of 1 to 2" overnight. Although winds may taper down a bit during the early evening as the gradient weakens a bit in advance of the surface trough, then pick up later in the night from west to east with the cold air advection/rapid pressure rises/and increasing momentum transport winds behind the trough. This will result in decreasing visibilities as the snow blows around, and the current Winter Storm Warning to Blizzard Warning remains valid for tonight into tomorrow, with winds at the top of the mixed layer running around 50 to 55 kts by Saturday. The biggest challenge will be how much of the the snow will be able to be lofted with the it being of the heavier variety and possibly slightly crusted over in some locales due to the mixed precipitation this evening. As for temperatures tonight, may see readings even warm slightly during the evening out ahead of the trough, then rapidly plunge with the passage of the boundary. Temperatures will then continue to fall into the single digits through mid to late morning on Saturday, before steadying out in the afternoon. Actual precipitation will move to the east by Saturday morning, though with the expected winds, as mentioned before, snow will be blowing around. .LONG TERM...(Saturday Night through Friday) Issued at 407 PM CST Fri Jan 17 2020 The cold air then continues to feed into the region behind the exiting system, with lows 5 to 10 below on Saturday night. With winds remaining rather stout into Sunday, wind chills will fall to 25 to 30 below in some areas, and Wind Chill headlines are going to be likely for that period. Arctic high pressure continues to build into the region for the beginning of the week, with highs on Sunday and Monday in the single digits to just below zero. There then appears to be a rather significant warm up for the middle of next week as the high pushes off to the east and a southerly flow returns to the region. Think the NBM guidance may be a little too aggressive with the warm up based on individual model guidance and snow cover across the area, though upper 20s to lower 30s seems reasonable for Tuesday through Thursday. Although there are model differences, could see some light precipitation over the area by Thursday. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1056 PM CST Fri Jan 17 2020 IFR ceilings and visibility are expected to prevail overnight. An Arctic front will blast through overnight, with the return of snow and strong northwest winds behind the front. Rapid onset of NW gusts at 30-50 kts and blizzard conditions will occur west to east, starting over the next few hours at KFSD/KSUX. Snow will end at TAF sites by 13z, but BLSN and gusty NW winds will linger through much of Saturday. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...Winter Storm Warning until midnight CST tonight for SDZ039-040- 054>056-061-062-066-067-070-071. Blizzard Warning until 6 PM CST Saturday for SDZ039-040-054>056- 061-062-066-067-070-071. Blizzard Warning until 3 PM CST Saturday for SDZ038-050-052-053- 057>060-063>065-068-069. MN...Winter Storm Warning until midnight CST tonight for MNZ071-072- 080-081-089-090-097-098. Blizzard Warning until 6 PM CST Saturday for MNZ071-072-080-081- 089-090-097-098. IA...Winter Storm Warning until midnight CST tonight for IAZ001>003- 012>014-020>022-031-032. Blizzard Warning until 6 PM CST Saturday for IAZ001>003-012>014- 020>022-031-032. NE...Winter Storm Warning until midnight CST tonight for NEZ013-014. Blizzard Warning until 6 PM CST Saturday for NEZ013-014. && $$ UPDATE...BP SHORT TERM...JM LONG TERM...JM AVIATION...BP