textproduct: Bismarck

KEY MESSAGES

- Snow and blowing snow with significantly reduced visibility today into early this evening in the James River Valley.

- Windy and cold today, with wind chills from 20 below to 35 below zero.

- Decreasing winds tonight, but still cold with lows 5 below zero to 15 below zero.

UPDATE

Issued at 1207 AM CST Sun Dec 28 2025

Although we expect only light additional snow accumulations, if at all, the strong winds are still producing lower visibilities. No changes to the current Winter Weather Advisory. We do expect winds to pick up a bit in the far southwest and south central this afternoon, so no changes here to the Wind Advisory. The one change we did make was to extend the Cold Weather Advisory through much of the afternoon. Current wind chills are hovering around 30 below, and as mentioned above think we'll see winds pick up a bit this afternoon. Also, the northwest may need to be extended through Monday morning, while the southwest probably will not need to be extended beyond this afternoon. This will give us some time to determine which counties, if any we will need to extend through tomorrow morning. Updated text products will be transmitted shortly.

UPDATE Issued at 838 AM CST Sun Dec 28 2025

Snow continues over the James River Valley and into eastern ND. Lingering very light snow continues over the rest of central ND. In the west, there is a break in the clouds over the southwest but that shouldn't last much longer as clouds and light snow associated with the mid-upper level low drop continue to drop southeast. Current forecast remains on track. The only change with the morning update was to switch Emmons county from a Winter Wx Advisory to a Wind Advisory. Accumulating snow has ended here. We do expect some blowing/drifting snow but with little impacts. We covered the minor impacts in the Wind Advisory. Wind chills in western ND remain around 30 below. Will monitor but will keep it going for now.

UPDATE Issued at 645 AM CST Sun Dec 28 2025

Based on observations showing wind chills around -30 F as of 12 UTC in parts of south central ND, we expanded the Cold Weather Advisory for this morning east another row of counties. Other- wise, the rest of the forecast is on track, with the initial band of snow continuing slowly eastward through the James River valley. Guidance continues to support the going Winter Weather Advisory in that area today into this evening. Upstream, the upper-level low is approaching southwestern ND, with several observations of flurries or light snow in its vicinity, which supports our low snow chances in western ND.

DISCUSSION

Issued at 402 AM CST Sun Dec 28 2025

Windy and cold weather is expected today, with snow and blowing snow impacts in parts of south central ND into the James River Valley. Continued cold temperatures are expected tonight, but winds will diminish. The early-week forecast will be relatively quiet with no impacts expected, though by midweek, medium chances of snow return to the forecast.

Early this morning a band of moderate snow continues to slowly progress through central ND, with visibilities occasionally as low as 1/2SM, but more commonly in the 1-2SM range, with snow accumulations on the order of 1-2 inches being observed so far. This snow band does appear to be moving a bit more slowly east than expected earlier, which may be the result of the middle- and upper-level flow being more southerly ahead of the upper- level low which is located in northeast MT at this hour. Water vapor imagery suggests that low may be a touch further south than many model simulations had suggested previously. That in turn may be resulting in the more meridional (southerly) flow aloft downstream and a slightly slower eastward progression of the snow band, which is being driven by an area of strong midlevel frontogenesis. The guidance that appears to have the best handle on the placement of the upper-level low supports observational trends in suggesting the band of moderate snow will move through the James River Valley through mid morning, with reduced visibilities in falling and blowing snow even if total accumulations remain on the order of 1 to 3 inches. As the upper-level low continues to move southeast, reaching southeast SD by this afternoon, an area of midlevel warm air advection and forcing on isentropic surfaces to its north suggests light snow will continue and/or "wrap-around" across the James River Valley through the day, even after the initial, frontogenesis- driven band of snow moves out of the area during the morning. NBM probabilities of 1 inch of snowfall in the James River Valley are high (70+ percent), and of reaching 2 inches are medium to high (on the order of 50 to 70 percent). As will be discussed further below, where falling snow overlaps with strong winds in the James River valley and parts of south central ND, significant blowing snow is expected today and into this evening.

We also included low chances of snowfall in central ND today in respect to uncertainty with how far west the "wrap-around" light snowfall will extend, and in parts of western ND this morning as the upper-level low itself crosses that part of the state.

A strong surface pressure gradient is forecast across the state today as an Arctic high pressure system on the order of 1040 mb approaches from southwestern Canada, and as a strong surface low pressure system rapidly deepens while moving across the Midwest and into the Great Lakes. The result will be a windy day, with forecast soundings suggesting mixing of 30 to 40 kt winds at the top of the boundary layer. Blowing Snow Model output suggests significant blowing snow in parts of south central ND and the James River valley, with visibilities of 1/2SM or occasionally as low as 1/4SM expected where falling snow combines with strong winds. Without significant pre-existing snowpack, the blowing snow impacts will be highly sensitive to falling snow, and how much snow falls given the relatively low accumulations that we are expecting. This does raise some uncertainty in the forecast, but we have high confidence in advisory-level blowing snow impacts where the Winter Weather Advisory has been issued. A low probability does exist for blizzard conditions to develop in parts of the advisory area, if snowfall rates become high enough. While that's a low-predictability outcome, it's a scenario we will be monitoring for closely in observational trends.

We did opt to extend the Wind Advisory in far southwest and far south central ND through the day, where the surface pressure gradient remains strong enough for marginal advisory-level winds today. Forecast soundings are marginal for advisory-level gusts, and we did consider allowing the advisory to expire as scheduled early this morning, but opted to extend it given recent trends in observed winds.

We also expanded the Cold Weather Advisory south to include all of western ND through the morning, with observed wind chills on the order of -30 F becoming widespread as of 09 UTC. Wind chills are forecast to slowly rise out of advisory range by afternoon, but it's possible some part of that advisory will need to be extended later pending observed trends.

Highs today are forecast to only range from zero to 10 above zero. We expect lows tonight to range from 5 below to 15 below zero, lowest in western and north central ND closest to the surface ridge axis that is forecast to move from western and into central ND overnight. The air mass will modify somewhat by tonight as the upper-level low exists the area, but we did lean on the colder edge (near the 25th percentile) of ensemble membership for forecast lows tonight. That's based on the position of the surface ridge axis, expected efficient radiational cooling, and observed temperatures underneath the ridge axis upstream in Alberta and Saskatchewan that are in the -10 to -20 F range. It is possible that some areas of western and central ND may be even colder than forecast tonight based on those upstream observations. While winds will be diminishing tonight, and will become light in western ND, we may need to extend or re-issue another Cold Weather Advisory since even light winds may cause wind chills in the -30 F range where actual air temperatures are coldest.

Northwest flow aloft is expected to prevail for much of the upcoming week across the Northern Plains in between a strong Hudson Bay Low and ridging in the western United States. The synoptic-scale pattern has strong confidence from ensemble guidance through midweek, but the regime is expected to yield a strong baroclinic zone and related temperature contrast across the region. The exact placement of that frontal zone carries lower predictability, and will be influenced by weak impulses embedded in the northwest flow. NBM guidance has relatively low spread Monday and especially Tuesday, when a general warming trend is forecast. Highs by Tuesday are broadly forecast to be in the 30s F across much of the area, again, with low spread in ensemble membership, resulting in high confidence in that part of the forecast. However, beginning Wednesday the spread in NBM guidance remains large, on the order of 20 degrees or more. As an example, at Bismarck, the reasonable range outcomes for high temperatures on Wednesday (New Years Eve) is from 8 F to 31 F. Similar spreads in temperature forecasts then continue through the latter part of the week, both due to uncertainty in exact location of the frontal zone, and due to uncertainty in how amplified the northwest flow aloft will be. That's related to the progression of an upstream trough in the Pacific ocean. The bottom line is that the temperature forecast is more uncertain than normal from Wednesday onward, and should be expected to change for some days and locations with later forecasts.

Precipitation-wise, ensemble guidance continues to highlight the Tuesday night and Wednesday timeframe for medium probabilities of snowfall as an impulse crosses the region in northwest flow. We would expect an axis of snowfall along and to the cool (north) side of the baroclinic zone, wherever it ends up exactly by that timeframe. NBM probabilities of 1 inch of snowfall are high in north central ND and the James River Valley in the time period centered on Wednesday, with medium probabilities of 2 inches or more of snowfall. Those probabilities diminish further to the southwest part of the state. Otherwise, low chances of snow are also included in the forecast next weekend based on a consensus of ensemble guidance, too.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1207 AM CST Sun Dec 28 2025

MVFR to IFR visibilities continue across much of western and central ND. Expect the lower visibilities in blowing snow to continue through the afternoon, given the strong winds, but will improve later this afternoon (west) into this evening (central) as winds subside. The James River Valley could see the lower vsbys continue into the early morning hours of Monday. Once visibilities improve at TAF sites, expect mostly VFR conditions at this time as high pressure builds over the area. Northwest flow will shift southwest over western TAF sites Monday morning.

BIS WATCHES/WARNINGS/ADVISORIES

Cold Weather Advisory until 4 PM CST /3 PM MST/ this afternoon for NDZ001-002-009-010-017>021-031>034-040>045. Winter Weather Advisory until 9 PM CST this evening for NDZ023- 025-036-037-047-048-050-051. Wind Advisory until 5 PM CST /4 PM MST/ this afternoon for NDZ040>046.