####018006686#### FXUS63 KBIS 082117 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 317 PM CST Mon Dec 8 2025 .KEY MESSAGES... - Freezing rain will impact North Dakota between midnight tonight and noon CST Tuesday with ice accumulations as high as one tenth of an inch. - Very strong winds expected late Tuesday morning through Tuesday night, with gusts as high as 65 mph. - 1 to 4 inches of snow are expected in the Turtle Mountains area Tuesday morning through Tuesday night. - Another round of snow will impact all of western and central North Dakota Wednesday afternoon through Thursday night. - Above average temperatures today and Tuesday, then below average expected for the rest of the week. Friday could be very cold with dangerous wind chills. && .DISCUSSION... Issued at 315 PM CST Mon Dec 8 2025 Currently northwest flow is over the Northern Plains. At the surface a warm front has moved east through North Dakota. Colder air sits in southern Canada awaiting to be pulled into the state by the backside of the low pressure system moving in tonight. Across western ND temperatures are above freezing post warm front, with breezy west winds. An Atmospheric River from the Pacific Ocean is flowing over the Northern Rockies creating a large high cloud shield over Montana and North Dakota. The Storm: Tonight an Alberta Clipper will start to move into the Northern Plains, tapping into that Pacific Ocean moisture. With the current northwest flow, there is warm air aloft ahead of the low across eastern Montana and North Dakota. This will create a swath of freezing rain as surface temperatures will be below freezing, moving west to east early Tuesday morning through about noon CST. A Winter Weather Advisory has been issued for this threat across most of western and central ND. We left the far southwest out because most of the precip will be farther north and east. If you are traveling to work in the morning be sure to check the road conditions. As the low moves through ND, and surface temperatures warm above freezing, it will switch to rain and the Winter Weather Advisory will expire at noon CST. The Turtle Mountains will be cooler and remain in the cold sector of the low, so mainly snow is expected. Current forecast totals are 1-4 inches with locally heavier amounts as you get closer to Canada and farther east into Towner County. The Winter Weather Advisory will remain there all day. QPF amounts are anywhere from 0.10 to 0.20 for the west and central. Closer to the northeast and east (the bullseye of the system) the amounts increase to 0.30 inches. A lot more snow will fall in the eastern part of the state where the cold sector and very strong frontogenesis with high lapse rates are located. Northeast ND will also be the left exit region of the jet stream, enhancing the lift and strength of the system. All that to say, snow amounts will be limited in our CWA by the length of time in the warm sector and lack of forcing. There will be a lull in precip in the afternoon before the wrap around moisture moves in from the north in the evening. This wrap around will mainly be snow, especially after sunset and through the overnight. Snow accumulations from Tuesday night will likely be below 1 inch and be limited to the Highway 52 corridor. For the winds, the pressure gradient will tighten in the late morning and combine forces with cold air advection (CAA) on the backside of the low. A strong pressure bubble will also be with the CAA, creating winds up to 65mph, possibly 70mph at times. We have a High Wind Warning out that will replace the Winter Weather Advisory at noon CST. The far southwest's Warning will start a tad earlier at 8am MST. The strong winds will reside Tuesday night, but breezy winds will continue through Wednesday morning. Blowing snow is also a concern but may be limited if the freezing rain puts a crust on the snow or if the rain soaks the snow enough to be too wet to be lofted. Likely either way there will be plenty of drifting snow across the roads Tuesday afternoon through the overnight. Rest of the week: Wednesday a Northern Rockies low will form and move through the state, bringing the next round of snow. Models continue showing strong frontogenesis setting up in a northwest to southeast diagonal across ND with jet stream support. Calibrated NBM probabilities for 1 inch of snow range from 20 to 50 percent. The higher chances are in the southwest where the frontogenesis may linger longer. Winds will not be as strong as Tuesday, only around 20mph. High temperatures will also be much cooler in the single digits in the northeast to the low 30s in the southwest (no snow pack). This snow system will linger into Friday. Northwest flow will then continue through the weekend, with very cold Arctic air dropping into the state. Lows starting Friday morning will be in the negatives statewide. Expect lows around 15 below in the north and 5 below in the south. This will make wind chill values of -25 to -40 across the state. This will need a Cold Weather product later this week. Saturday morning will be similar and Sunday morning will be slightly warmer but will still have wind chills around -20. In the northwest flow through the weekend, small waves will form off the Rocky Mountains, bringing low to medium (20-40%) chances of snow to North Dakota. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 315 PM CST Mon Dec 8 2025 MVFR to VFR today. Winds will be westerly and breezy this afternoon before gusting near 55kts Tuesday. Periods of freezing rain are likely early Tuesday morning before switching to rain through Tuesday afternoon. && .BIS WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from midnight CST /11 PM MST/ tonight to noon CST /11 AM MST/ Tuesday for NDZ001>003-009>012-017>023- 025-033>037-041-042-044>048-050-051. High Wind Warning from noon CST /11 AM MST/ to 9 PM CST /8 PM MST/ Tuesday for NDZ001>003-009>012-017>021. Winter Weather Advisory from 4 AM Tuesday to midnight CST Tuesday night for NDZ004-005-013. High Wind Warning from noon CST /11 AM MST/ Tuesday to 3 AM CST /2 AM MST/ Wednesday for NDZ022-023-025-033>037-041-042- 044>048-050-051. High Wind Warning from 8 AM to 8 PM MST Tuesday for NDZ031-032- 040-043. && $$ DISCUSSION...Smith AVIATION...Smith ####018007333#### FXUS63 KFSD 082119 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 319 PM CST Mon Dec 8 2025 .KEY MESSAGES... - Fog and low level stratus remains along and east of I-29 this afternoon. A Dense Fog Advisory remains in effect until 10 pm this evening. Slick spots are possible on roads and untreated surfaces. - Confidence remains high in strong winds impacting the area for Tuesday through Wednesday morning. A Winter Storm Watch for Blizzard conditions has been issued for the vast majority of the area. A High Wind Warning has been issued for Gregory, Charles Mix, and Brule counties. Winds up to 50 to 60 mph is expected in both headlines. Blowing snow will be the main impact where visibilities down to a quarter of a mile is possible. - Chances for snow will persist throughout the week and into the weekend. At this time, snowfall amounts look to be light with each chance. - Much colder temperatures are expected from the middle of the week through the weekend. Cold Weather headlines may be needed. && .DISCUSSION... Issued at 318 PM CST Mon Dec 8 2025 Low level stratus and fog persists across the area this afternoon. The fog is being driven by weak southerly moisture advection, keeping the boundary layer saturated. The stratus and fog have begun to nudge eastwards as low level winds begin to take on a more westerly component thanks to an advancing warm front. Thus, have left the Dense Fog Advisory in effect through 10 pm for locations along and east of I-29. Trends will be monitored through the rest of today to see if any further reductions are needed in the Advisories extent. Tonight will be quiet with low temperatures falling to the 20s to up to about 30F. Things begin to change on Tuesday as a strong upper level shortwave trough pushes through the Northern Plains. This will bring a round of precipitation to the area beginning Tuesday morning. Precipitation looks to begin as light freezing rain before transitioning to plain rain as temperatures warm through the morning hours, thanks to persistent warm air advection (WAA) aloft. A few places might see a light glaze of ice for a brief period of time during the morning and early afternoon hours before plain rain melts away the ice. The afternoon will still see some cooler temperatures across the area thanks to persistent cloud cover and current snowpack across the majority of the area. Have highs only warming to the mid 30s east of the James River up to the 40s and 50s west of the River. The bulk of the rain will push east of the area by the late afternoon hours. The other component to Tuesday will be strengthening winds during the afternoon hours as a strong cold front will pushes through the area. A strong shot of cold air advection (CAA) is expected with the passing front, resulting in very strong winds across the entire area. The strongest winds will come during the evening and overnight hours where gusts up to 50 to 60 mph is likely (>=70% chance). These strong winds will be capable of blowing the current snow pack around which can result in blowing snow across most of the area. The main uncertainty regarding the extent of the blowing snow is due to the previously mentioned rain and temperatures warming above freezing. The rain and warmer temperatures will likely melt some of the snow pack. Even with the quickly falling temperatures behind the front, questions remain how blowable the snowpack will be. As such, have issued a Winter Storm Watch for Blizzard Conditions from noon on Tuesday through noon Wednesday. A High Wind Warning has been issued for Gregory, Charles Mix, and Brule counties due to these counties having a much lower snowpack to non existent snowpack. The High Wind Warning is in effect from noon Tuesday through 3 am Wednesday. Winds will be weakening during the morning hours on Wednesday as high pressure slides through the Northern Plains. Tuesday will be the last "warm" day across the area before a much colder airmass settles into place for the rest of the week. Highs will be below average in the 20s to down to the teens and single digits come Friday through the weekend. With such cold temperatures in place along with light winds in place, Cold Weather headlines may be needed. Highs may trend back towards seasonable come early next week. For precipitation chances, there looks to be persistent chances for snow throughout the week. Currently, the highest chances (30-40%) for snow looks to come on Thursday. Though additional chances will persist through the weekend. Given how these are all clipper systems, light snowfall is most probable with each passing clipper at this time. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 1134 AM CST Mon Dec 8 2025 Latest satellite imagery shows low level stratus and fog across the majority of the area. Ceilings and visibilities range through the entire set of flight categories from VFR to LIFR. VFR conditions are present across parts of south central South Dakota with all other lower categories along and north of I-90 and the entirety of northwest Iowa. With weak southerly low level winds in place, think the fog and stratus will persist through the rest of the daylight hours. Winds then begin to take on a westerly component late this afternoon and evening. Think that the fog and stratus will begin to push eastwards and clear all TAF terminals and the entire area as this westerly component kicks in. Winds will turn back to out of the south/southwest by tomorrow morning. The next chance for precipitation looks to return to the area by the end of the TAF period. This looks to be generally along and north of highway-14. Precipitation will be in the form of light freezing rain before transitioning to plain rain. Low level wind shear (LLWS) is also possible to end the period as well by KHON. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...Dense Fog Advisory until 10 PM CST this evening for SDZ040-055- 056-062. Winter Storm Watch from Tuesday evening through Wednesday morning for SDZ067-070-071. Winter Storm Watch from Tuesday afternoon through Wednesday morning for SDZ038>040-052>056-058>062-064>066-068-069. High Wind Warning from noon Tuesday to 3 AM CST Wednesday for SDZ050-057-063. MN...Dense Fog Advisory until 10 PM CST this evening for MNZ071-080- 081-089-090-097-098. Winter Storm Watch from Tuesday evening through Wednesday morning for MNZ080-081-089-090-098. Winter Storm Watch from Tuesday afternoon through Wednesday morning for MNZ071-072-097. IA...Dense Fog Advisory until 10 PM CST this evening for IAZ001>003- 012>014-020>022-032. Winter Storm Watch from Tuesday evening through Wednesday morning for IAZ001>003-012>014-020>022-031-032. NE...Winter Storm Watch from Tuesday evening through Wednesday morning for NEZ013-014. && $$ DISCUSSION...Meyers AVIATION...Meyers