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KEY MESSAGES

- Freezing rain will impact most of western and central North Dakota late overnight through this morning morning, with ice accumulations as high as one tenth of an inch.

- Very strong winds expected late this morning through tonight, with gusts as high as 65 mph.

- 1 to 4 inches of snow are expected in the Turtle Mountains area this morning through tonight.

- Another round of snow will impact all of western and central North Dakota Wednesday afternoon through Thursday night.

- Below average temperatures are expected Wednesday through the upcoming weekend, with dangerous wind chills possible Thursday evening through Saturday morning.

UPDATE

Issued at 1200 AM CST Tue Dec 9 2025

Patch to areas of fog continue to be found over portions of central North Dakota into the James River Valley at the time of this mid night update. Visibilities have occasionally dropped to as low as 1/4 miles, though these have been fairly brief so far. Looking through NDDOT cameras, it appears that much of this fog is constrained to small fog banks scattered around the affected area. While visibility within these banks are poor, their small size means that they move off fairly quickly. If any location were to see a slightly more cohesive mass of fog, it would probably be in the northern James River Valley over the next few hours. That being said, mid to high based clouds moving out of the west are quickly overrunning the fog, and may help limit this development.

UPDATE Issued at 1047 PM CST Mon Dec 8 2025

Quick update to add patchy to areas of fog to the forecast over central ND through about 10 UTC based on observed trends which have fog developing on the edge of a stratus deck. This is no doubt aided by boundary layer moisture enhancement resulting from above-freezing temperatures over the snowpack today, and from the relatively sharp low-level inversion that's in place.

UPDATE Issued at 1005 PM CST Mon Dec 8 2025

Given the consensus of recent CAMs and other incoming 00 UTC model suites, we delayed the start time of the Winter Weather Advisory in western ND slightly until 1 am CST, and longer in central ND until 4 am CST. This was done in order to convey that impacts will not begin until later in the night, but we need to emphasize that once precipitation begins to develop, guidance suggests it will do so quickly, with increasing impacts quickly to follow. Forecast soundings suggest top-down saturation will only take 1-2 hours once low- and midlevel ascent arrives in any given location, and thermal profiles continue to display the requisite configuration for freezing rain with a warm nose aloft on the order of +3 to + 6 C atop a shallow, subfreezing surface layer. The 00z KABR RAOB reflected this thermal profile already, too. Note that surface temperatures are still expected to also warm above freezing from west to east Tuesday morning, but there is apt to be a lag between when surface temperatures exceed 32 F and when ground conditions warm above that threshold. We held off adding any of the remainder of far southwest ND to the Winter Weather Advisory with this update, since recent guidance suggests the greatest precipitation will be east of that area, but trends will be monitored closely in case a short-fuse expansion is needed. Otherwise, we updated hourly forecast fields with this update based on recent rapid- refresh model guidance. The overall forecast theme underwent only minor changes in timing, but we did increase precipitation chances into the 80-100 percent range over more of the area Tuesday morning.

UPDATE Issued at 635 PM CST Mon Dec 8 2025

Little change is needed to the forecast, and there were no changes to the Winter Weather Advisory and High Wind Warning with this update. As of early evening, a weak surface low is near Devils Lake and moving southeast out of the area. The midlevel air mass west and southwest of that system is very warm, with the 18z KBIS RAOB having already sampled a warm nose aloft that was around +3 C in the 900 to 850 mb layer. That will set the stage for freezing rain late tonight and Tuesday morning as forcing for ascent increases as a low- and midlevel warm front tied to a rapidly-deepening surface low in southern Canada and an associated intense jet streak aloft move across western and central ND. The 18 UTC global model guidance and recent rapid- refresh guidance remains in agreement on this scenario, so no changes were needed to our messaging at this time. We will need to carefully consider whether the rest of southwestern ND not already in a Winter Weather Advisory will need one for freezing rain for a few hours late tonight and Tuesday morning, but that area will be closest to the surface freezing line when precipitation develops. Otherwise, the incipient surface low with the upcoming system is in west central Alberta as of this writing, with water vapor imagery suggesting the intensifying upper-level jet streak that will foster its rapid strengthening the next 12 hours beginning to spread east across the Rockies.

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 /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1200 AM CST Tue Dec 9 2025

An area of IFR to MVFR stratus will continue to effect parts of east central ND into the James River Valley through late tonight, and areas of fog near and on the edge of the stratus deck could result in localized MVFR to IFR visibilities, including at KMOT and KBIS.

High-impact aviation weather is expected late tonight and Tuesday. We still expect freezing rain to begin in western ND between 07 and 10 UTC, and in central ND between 10 and 12 UTC. We expect a few hours of freezing rain at all terminals in western and central ND late tonight and Tuesday morning, before temperatures rise above freezing and precipitation turns to rain, then gradually diminishes from west to east. The exception wil be in far north central ND, e.g., the Turtle Mountain region, where snow is expected Tuesday and into Tuesday evening. MVFR to IFR ceilings are also expected with this precipitation late tonight and Tuesday morning. Low-level wind shear will develop late tonight and Tuesday as well, with westerly winds of 45 to 55 kt as low as 1500 AGL. Strong westerly surface winds will also develop from Tuesday morning into the early afternoon, before increasing further and turning more northwest, with peak gusts to around 50 kt Tuesday afternoon and Tuesday evening.

BIS WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory until noon CST /11 AM MST/ Tuesday for NDZ001-002-009-010-017-018-033-041-044. 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 CST /3 AM MST/ to noon CST /11 AM MST/ Tuesday for NDZ003-011-012-019>023-025-034>037-042- 045>048-050-051. 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.