textproduct: Bismarck

KEY MESSAGES

- A high-end wind event is expected across western and central North Dakota this afternoon through Thursday morning, with widespread maximum gusts ranging from around 60 mph in the Turtle Mountains area to as high as 75 mph in the southwest.

- A period of accumulating snow is expected with the very strong winds late this evening into Thursday morning, with forecast totals ranging from around one half inch along the South Dakota border to around 2 to 4 inches in far northwest and north central North Dakota.

- The very strong winds combined with the snow may produce blizzard conditions across northern and eastern parts of the state, and a shorter-duration period of dangerous whiteout conditions (snow squalls) in the west and south central.

UPDATE

Issued at 848 AM CST Wed Dec 17 2025

Forecast overall remains on track with limited updates needed at this time. Weak returns starting to show up on radar in the north and in eastern Montana. The northern returns should push into Canada, while the returns in eastern Montana are forecast to get more organized later this morning and bring chances for rain from west to east today. Overall this is on point with current forecast, thus limited changes needed.

UPDATE Issued at 638 AM CST Wed Dec 17 2025

The near-term forecast remains on track. Current conditions and trends were blended in for this update.

DISCUSSION

Issued at 513 AM CST Wed Dec 17 2025

A well-advertised powerful Alberta clipper with forecast minimum MSLP as low as 980 mb will impact the Northern Plains this afternoon through Thursday. Already very high confidence continues to increase that this will be a high-impact event for our forecast area, with whiteout conditions and very intense wind gusts. The highest probabilities for blizzard conditions (at least 3 hours of 1/4 mile visibility) are generally along and to the north and east of Highway 52, while the potential for extreme wind gusts increases to the south and west.

Little to no notable weather is anticipated until early this afternoon, although broad mid level warm air advection could produce some very light "freezing sprinkles" falling through a warm and dry layer aloft this morning. Measurable precipitation is not anticipated from this. Early this afternoon, an initial surge of cold air advection with strong pressure rises is forecast to punch into western North Dakota, preceded by an area of rain showers. North central parts of the state are less likely to feel the brunt of this initial burst of winds, but there is potential for mixed precipitation in the Turtle Mountains area late this afternoon and evening, which may include freezing rain producing a light glaze of ice accumulation. Back to the south and west, temperatures should remain above freezing during the initial period of high winds, which forecast soundings indicate could be as high as 55 to 65 mph. This period of stronger gusts is likely to be shorter-lived and less impactful than what is to come.

Most ensemble guidance has consolidated on a double-barrel surface low crossing southern Saskatchewan through the northern Red River Valley, which is a slight northward shift from what a couple of global ensemble clusters had been suggesting. Even if the low does end up taking a slightly more southward path, which there are low probabilities for, that would not change the expected impacts and magnitude thereof. All locations will see a period of very intense winds (even by North Dakota standards) as the Arctic cold front plows through late this evening into early Thursday morning. The only missing ingredient for a high- impact wind event is the nocturnal timing, but this should be compensated by all other ingredients being objectively or subjectively near or at climatological maxima. Deterministic models project 3-hour pressure rises on the order of 15-20 mb with steep low level lapse rates despite the time of day. Model sounding analyses in BUFKIT also shows very strong downward momentum transfer of mean mixing layer winds that are forecast to be at least as strong as 50-65 kts. A wind gust EFI at the maximum value of 1 with a shift-of-tails greater than 2 over western North Dakota also implies high confidence in a high- impact event.

We have high confidence that winds will be strongest in the southwest and relatively "weakest" in the Turtle Mountains area, although gusts to around 60 mph are still anticipated there. The timing and duration of the strongest winds will vary by location, but can generally be summarized as mid evening to mid Thursday morning west; late evening to early Thursday afternoon south central; and late tonight to late Thursday morning north central.

There are some concerning signals emerging in rapid-refresh guidance that need to be addressed, but we emphasize these are still low-probability outcomes. HRRR/RAP soundings at Bowman have been consistently showing the top of the mixed layer to contain winds as high as 100 kts (115 mph), and the midway point of the mixed layer easily has winds in the 70-80 kt (80-90 mph) range. This occurs when all the aforementioned ingredients for maximum momentum transfer potential are forecast to be present, along with medium to high precipitation chances (more on that below). Other deterministic model soundings are not that extreme, but still show around 75-85 kts at the top of the mixed layer and around 65-75 kts at the midway point. We cannot recall seeing a wind signal like this since the January 2021 wind event that produced isolated gusts as high as 90 mph. The 100 kts mixing down to the surface would be a worst-case scenario and is borderline unreasonable (but not impossible). But given the lowest mixing potential in the southwest seems to be at least as high as 65 kts, we are advertising a reasonable high-end outcome of widespread maximum gusts to around 75 mph in southwest North Dakota. We anticipate there will a few sporadic gusts in the 80 to 90 mph range, and it would not be shocking to see a higher terrain location or two (such as on top of a butte) to record a triple digit wind gust. Even with the more conservative wind gust outcome, the strength of these winds will be similar to those commonly found in severe thunderstorms during the summer, and can be expected to cause at least minor property damage.

If the intense winds were not enough, they are expected to be accompanied by accumulating snow. There are high probabilities for at least 2 inches of snow along and north of a line from Crosby to Minot to Devils Lake, and low to medium probabilities for exceeding one inch reach as far south as the South Dakota border. Latest model/ensemble guidance has slightly increased amounts/threshold probabilities from previous forecasts at most locations.

Prior to the arrival of the Arctic cold front and new snowfall, whatever is left of snow already on the ground should not be blowable (note: wind gusts as high as +70 mph have been known to break through crusted snow packs, but snow may be nearly, if not completely melted in areas with the highest potential for gusts that strong). Whatever snow does fall in the strong winds is certain to produce whiteout/blizzard conditions, but there is still some uncertainty on the duration and intensity of blizzard conditions even where forecast snow amounts are highest. With the increase in forecast snow amounts, we have opted to expand the Winter Storm Watch for blizzard conditions southwestward into Divide, Mountrail, Sheridan, Wells, Foster, and Stutsman Counties, and maintain the pre- existing watch as is. All counties not under a Winter Storm Watch have been upgraded to a High Wind Warning.

Counties that are under a High Wind Warning will not remain void of hazardous winter weather. In fact, we have medium to high confidence that the Arctic cold front will produce snow squalls that meet Snow Squall Warning criteria. Virtually all known researched ingredients that support snow squall formation and maintenance are forecast to be present, including all previously mentioned ingredients for high winds, a strong 0-1 km theta-e gradient, strong low level frontogenesis, SBCAPE as high as 100 J/kg, and a snow squall parameter as high as 10 (values of just one are sufficient)! This phenomenon would likely only last for an hour at most at any given location. But the combination of the intense winds with the burst of snow could create an extremely hazardous travel situation. We cannot overstate the danger of being caught on rural highways in snow squalls, as visibility can go from "as far as the eye can see" to zero in a matter of seconds. The highest snow squall potential is across western and south central North Dakota this evening through tonight. This includes Highway 85 from Williston to the South Dakota border, and Interstate 94 from the Montana border to Bismarck. It is crucial that travelers in this part of the state remain weather aware this evening and tonight, and strong consider altering their travel plans.

Temperatures will plummet behind the Arctic front, with widespread wind chills in the 20s below. A Cold Weather Advisory may be needed for far northern parts of the state, where wind chills could fall as low as 35 below. The Arctic air mass will be short lived though as yet another but much weaker clipper system crosses the region late Thursday through Friday. The NBM shows temperatures rising above freezing across the western half of the state Friday afternoon, but this may be proceeded by a period of light mixed precipitation in the morning. Guidance favors a drier pattern this weekend leading up to Christmas, but with fluctuating temperatures for which there remains large ensemble spread.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 638 AM CST Wed Dec 17 2025

Significant aviation impacts are expected across western and central North Dakota throughout the forecast period, especially this evening through tonight.

VFR conditions should prevail through this afternoon, although there could be some brief MVFR visibility restrictions with a band of rain moving across the state from west to east. Southerly winds will increase and turn westerly through this afternoon and evening, becoming very strong in western North Dakota by late evening with +50 kt gusts. Widespread low level wind shear is also forecast through this evening.

A very strong cold front will move across the state from northwest to southeast this evening through tonight, with northwest winds around 35 kts and gusts as high as 55 kts (perhaps stronger in southwest North Dakota). Snow is also expected with and trailing the frontal passage, which may produce near-whiteout conditions at times.

BIS WATCHES/WARNINGS/ADVISORIES

Winter Storm Watch from 6 PM CST this evening through Thursday morning for NDZ001>005-010>013. High Wind Warning from 2 PM CST /1 PM MST/ this afternoon to noon CST /11 AM MST/ Thursday for NDZ009-017-018-031>033-040- 041-043-044. High Wind Warning from 5 PM CST /4 PM MST/ this afternoon to 3 PM CST /2 PM MST/ Thursday for NDZ019>021-034>036-042-045>048- 050-051. Winter Storm Watch from late tonight through Thursday afternoon for NDZ022-023-025-037.