textproduct: Bismarck

KEY MESSAGES

- Another area of light snow is expected to cross the state from west to east today, with snow accumulations around one half to near 2 inches.

- A more impactful system is forecast Monday night through Tuesday night, which may bring a period of freezing rain, accumulating snow (highest chances north and east), and very strong winds to parts of western and central North Dakota.

- The active pattern continues through the middle of the week, with medium chances for another round of accumulating snow late Wednesday through Thursday.

- Cold today, followed by above average temperatures Monday and Tuesday, then back below average for the second half of the week. Friday could be very cold with dangerous wind chills.

UPDATE

Issued at 1204 PM CST Sun Dec 7 2025

Band of snow has developed from northwest to south central North Dakota late this morning. Expect this band to push eastward today through this evening. Light to moderate snow is currently being observed, and may continue through today. Issued an SPS to inform of some impacts with this snow band. Snow accumulations are still expected to be below advisory criteria, and generally 1 to 2 inches. Breezy winds with this system is also bringing some patchy blowing snow, especially in the more open areas. There is still a signal for patchy freezing drizzle after snow ends, which has now been added, along with patchy blowing snow, to the forecast.

UPDATE Issued at 942 AM CST Sun Dec 7 2025

Band of mainly light snow in western ND will push eastward today. Accumulations still look to be on the lighter side and generally 1 to 2 inches. Some increased southerly winds ahead of this system may bring some patchy drifting snow, although the blowing snow model did not produce much for blowing snow when ran. As the wave moves eastward and snow diminishes behind it, there could be a brief window of freezing drizzle/mist. Upstream reports have not indicated this is currently occurring, thus confidence was too low to include in the forecast at this time and will be monitored for future updates.

UPDATE Issued at 635 AM CST Sun Dec 7 2025

Snow has moved into western North Dakota, as far east as around Williston to Hettinger as of 630 AM CST. Local radar imagery and surface visibility observations indicate moderate snowfall rates, but not lasting for more than an hour or two at any given location. Current observations and trends have been blended into the forecast for this update. Overall, the forecast for today remains on track.

DISCUSSION

Issued at 513 AM CST Sun Dec 7 2025

A surface ridge axis across Manitoba and the eastern Dakotas has allowed early morning temperatures to plummet, with widespread observed lows around 5 to 20 below zero. There have been a few instances of wind chills as low as 30 to 35 below, but winds have mostly remained light except in the far west where temperatures are now rising. A mid level shortwave/low level warm front will bring a band of light snow across the state from west to east this morning through this evening. The snow was already crossing the Montana border around Beach and to the south at the time of this writing. QPF threshold probabilities have been consistently high for at least 0.01", medium for at least 0.05", and very low for greater than 0.1". With ensemble snow ratios around 15:1 to 20:1, this yields medium to high confidence in snow totals around one half to near 2 inches. The NBM has focused its highest snow probabilities more over the southern half of the state compared to the north, but we anticipated at least a few tenths of an inch across all of western and central North Dakota by the end of the day. It will remain cold for most of the state today, but with a slight warmup in the west compared to yesterday. Highs this afternoon are forecast to range from the single digits above zero east to near 30 in the southwest corner of the state.

Another shortwave crossing central Canada will bring a Pacific warm front across the state late tonight into Monday morning. Some CAMs hint at scattered light precipitation accompanying the warm front, which is a conceptually and climatologically favored outcome with this type of feature. The light precipitation would almost certainly fall as freezing rain, but the probability of of impactful icing at any location is no greater than 15 percent. As the parent shortwave dives into the Red River Valley Monday afternoon, some snow or mixed precipitation could clip the Turtle Mountains, with only low chances for impactful winter weather at this time. Monday will be much warmer, with highs mostly in the 30s outside of the Turtle Mountains and Devils Lake Basin. But it will also be windy on Monday, with westerly winds around 20 to 25 mph and afternoon gusts as high as 35 mph.

Confidence continues to increase that a powerful clipper system will impact the region Monday night through Tuesday night. The main concern for Monday night into Tuesday morning is the potential for freezing rain. There are medium to high probabilities for measurable precipitation across the western half of the state over this time period, and high confidence in above freezing temperatures aloft. The uncertainty is with surface temperatures, which are forecast to steadily rise during the late overnight and morning hours but could fall below freezing before the warmup commences. NBM temperature probabilities prior to sunrise generally show low potential for sub- freezing surface temperatures in the southwest, and a medium to high potential elsewhere. This could result in a period of impactful ice accumulation, but greater than a tenth of an inch of ice appears highly unlikely. The highest probabilities for icing are across northwest and central North Dakota.

00Z ensemble cluster analysis shows little spread in the timing and track of the surface low, but there are subtle differences in the QPF/snow fields worth pointing out. Two clusters with around 55 percent membership show the major axis of highest QPF cutting through north central North Dakota. The other two clusters show the same feature shifted farther west into northwest North Dakota, but the eastern edge of these major axes in both clusters are near Fargo. The former of these sets of clusters also contains higher QPF (high chances for at least 0.25") and snow (medium to high chances for at least 3 inches) probabilities than the latter, both focused across north central North Dakota. Snow probabilities drop off significantly to the south and west, where afternoon temperatures are forecast to rise well above freezing, perhaps as warm as the mid 40s. There is still a potential for lighter snow in south central North Dakota with the cold front surging southeastward later in the day.

The most impactful aspect of the Tuesday system will likely be very strong winds across western and south central North Dakota. Every ensemble cluster now has a large area of mean 850 mb winds in the 55-60 kt range, and deterministic soundings confirm this is a reasonable approximation for mixing heights. All requisite ingredients for maximum momentum transfer are forecast to be present, including strong cold air advection, strong pressure rises, tightly packed isobars and isotherms, steep low level lapse rates, and a favorable time of day. If these forecast signals hold, a High Wind Watch will eventually be needed.

An active northwest flow pattern is favored to continue through the rest of the week. The highest chances for accumulating snow beyond Tuesday are with an upper level jet streak ejecting off the Northern Rockies Wednesday night into Thursday, but forecast details on amounts and locations thereof remain uncertain (there are slightly higher odds to the west compared to the east). There is however increasing confidence in temperatures becoming much colder for the second half of the week, especially from Thursday night through Friday night when ensembles favor a strong Arctic intrusion. The NBM shows medium to high probabilities for highs below zero on Friday, along with medium probabilities for lows around 15 to 25 below both Thursday and Friday nights. This bitterly cold air mass could be accompanied by enough of a northwest breeze to cause wind chills to fall to dangerous levels. Deterministic-based NBM wind chill projections are currently as cold as 35 to 45 below zero Thursday night into Friday morning.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1204 PM CST Sun Dec 7 2025

Band of snow will bring MVFR to IFR conditions today as this band moves from west to east. Breezy winds this afternoon could also bring some patchy blowing snow. As snow diminishes, patchy freezing drizzle is also possible today through this evening. Snow will taper off this evening, although lingering low clouds could bring some MVFR ceilings through the night. Some sites could see these ceilings lower to IFR heights tonight, although confidence in where this occurs is low to moderate at this time. A mix of MVFR to VFR clouds cold then be found Monday morning. There is a PROB30 chance for freezing rain and/or snow at KXWA Monday morning. Westerly winds will go on the rise Monday, this could bring some low level wind shear starting Monday morning. Confidence was only high enough to include at the KDIK TAF at this time.

BIS WATCHES/WARNINGS/ADVISORIES

None.