textproduct: Bismarck

KEY MESSAGES

- Low chance for a wintry mix of light snow and freezing rain late this evening and overnight, mainly north into the James River Valley.

- Warmer on Tuesday, with a large spread in temperatures from northeast to southwest for the mid to late week.

- A clipper system will bring low to medium chances for snow to mainly northwest and central North Dakota Tuesday night into Wednesday.

DISCUSSION

Issued at 253 PM CST Mon Dec 29 2025

This afternoon, a closed low was analyzed over the Great Lakes region, with the attendant trough digging into the Midwest and upstream cyclonic flow aloft across the Northern Plains. At the surface, high pressure extended over southern South Dakota and the central Plains, with a low centered in northern Saskatchewan. A warm front extended south of the surface low through western North Dakota, with a shift to more westerly winds behind the front. Some widespread mid-level clouds continue on the cool side of the front, with afternoon highs ranging from the teens in our eastern counties to around freezing in southwest North Dakota.

A big forecast question with this update is precipitation chances and type with a few impulses moving through the mean northwest flow this evening, overnight, and into Tuesday morning. As the warm front continues pushing east, high-res guidance wants to produce light snow in north central North Dakota and the James River Valley, so we do have some low POPs to account for this later this evening. As the surface low then tracks southeast through the southern Canadian Prairies, another impulse and boundary drops south and a swath of light precipitation is projected to move north to south through much of the forecast area late tonight into Tuesday morning. With this wave, there has been a modest increase in a freezing rain signal, with forecast soundings showing a few hours of enough of a warm nose to melt hydrometeors with sub-freezing surface air temperatures. Although QPF amounts look very light, we have seen multiple times already this winter that it takes very little freezing rain to lead to surface impacts. We have increased messaging for this potential, and are highlighting the northwest into much of central North Dakota for a low chance of a glaze of ice. This could potentially impact the Tuesday morning commute. There could also be a dusting of snow in the Turtle Mountains area. We have issued a Special Weather Statement to cover the wintry mix potential.

As this weak system moves out on Tuesday, we get a brief reprieve and warmup, with forecast highs in the 30s. A clipper system then quickly slides along a baroclinic zone that gets established across the state, introducing chances for snow late Tuesday night into Wednesday. Snow chances are primarily limited to north central and eastern North Dakota, with relatively good agreement on this being a light snow event of 1 to 2 inches, as internal probabilities based on the gridded forecast give a 10 percent chance of exceeding 3 inches of snow. However, as the previous shift noted, there is enough of a signal for at least moderate frontogenesis and lapse rates that we can't rule out some banded snowfall, which gets washed out in blended probabilities.

Wednesday through the remainder of the week, we are expecting a large range in temperatures from northeast to southwest, with highs mainly in the teens in the far north central and east, to the 30s southwest. With persistent cyclonic flow aloft favored, we would not be surprised for some additional light precipitation events during this period, but predictability at this juncture is quite low. Uncertainty in the overall pattern increase late in the weekend into next week, when NBM 25th/75th temperature percentiles have quite a large spread due to ensemble members being split on how the synoptic flow progresses.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1159 AM CST Mon Dec 29 2025

VFR conditions expected through the majority of the TAF period. This evening through late tonight, there is a low chance for a wintry mix across northern North Dakota into the northern James River Valley. Confidence is still too low to include mention at any terminal with this update, with light snow potentially transitioning to light freezing rain, although little accumulation is expected. Light west to southwest winds to start the TAF period will become more northwesterly and gusty late tonight into Tuesday morning.

BIS WATCHES/WARNINGS/ADVISORIES

None.