textproduct: Bismarck

KEY MESSAGES

- Areas of fog and mist across the western half of the state this morning, with periods of light snow to the east.

- A winter storm will impact the region late tonight through Saturday. There are high chances for exceeding 6 inches of snow and low to medium chances for exceeding 12 inches across the southern half of the state.

- Medium to high chances for a brief period of freezing rain along the South Dakota border late tonight into Friday morning.

- Gusty northwest winds could cause areas of blowing snow in south central and eastern North Dakota on Saturday.

DISCUSSION

Issued at 433 AM CDT Thu Apr 2 2026

Broad southwest flow aloft over the Northern Plains early this morning, with a mid level impulse traveling into the southern Red River Valley. This wave will prolong snow chances in the James River Valley through this afternoon, though the strongest forcing is expected to remain farther east. A 700 mb low could spin-up over Minnesota this afternoon and extend its cyclonic vorticity field back into central North Dakota in the fashion of an inverted trough. Should this happen, only minor snow accumulations would be expected. Elsewhere this morning, a lower tropospheric layer of deep saturation being maintained by easterly flow is producing areas of fog, mist, and at times light freezing drizzle. Given the antecedently warmer ground conditions and near-surface air temperatures just slightly below freezing, we do not anticipate travel to be majorly impacted this morning. But there could be some slick spots on untreated and elevated surfaces, such as bridges. Fog and mist should slowly burn off from mid morning to early afternoon, and freezing drizzle will no longer be a threat after mid morning. The rest of the day should remain quiet but gloomy, with an overcast sky and highs mostly in the 30s.

A strong upper level low spinning into the Pacific Northwest this morning will cross the Northern Rockies tonight and reach the Northern Plains on Friday. This system will bring heavy snow across southern and eastern North Dakota beginning in the southwest late tonight, spreading eastward through Friday morning, expanding northeastward Friday afternoon, and ending from west to east late Friday night through Saturday morning. All ensemble systems show very high confidence in a swath of at least 6 inches of snow along and to the south of a line from around Beach to Harvey. Threshold probabilities for exceeding a foot of snow have mostly been in low to medium categories and focused over far south central North Dakota. But newly arriving NBM data that has not yet been incorporated in our published forecast products have taken a significant jump, with both operational and experimental NBM guidance now showing a larger area of a 60 to 80 percent chance of at least a foot of snow. However, the threshold probabilities for an inch of QPF, which would be roughly equivalent to a foot of snow given forecast snow-to-liquid ratios, are quite different between the two, with the experimental version being much lower (around 30 to 50 percent) and displaced farther south (higher percentages over northern South Dakota). Also to be considered is that higher-end QPF events such as this tend to verify with snow-to-liquid ratios under 10:1. These considerations give us some skepticism in widespread 12 to 18 inch amounts, but the difference in expected impacts between 8 to 12 inches and 12 to 18 inches is not that great. Most, if not all of the Winter Storm Watch will need to be upgraded to a warning later today. The lowest snow probabilities with this system are along and north of Highway 2, where there are only low chances (less than 40 percent) for exceeding 4 inches of snow.

There are a few additional non-snowfall related aspects of this system to be discussed. As an initial mid level vort max kicks into southwest North Dakota this evening, there may be enough elevated CAPE to allow a few thunderstorms to develop, with all hydrometeor types in play (rain, freezing rain, snow, sleet, graupel, small hail). This potential threat should greatly diminish after midnight. From late this evening through mid Friday morning, there could be enough warm air aloft wrapped into the system to produce sleet or freezing rain as a dominant type at the onset of precipitation along the South Dakota border. The highest probabilities for ice accumulations are from Sioux County to the southern James River Valley. But given the time of year, short duration, and subsequent heavy snowfall, this is not expected to be a critically impactful aspect of the system at this time.

Through the duration of falling snow, winds are not forecast to exceed sustained speeds of 20 mph, and gusts should mostly remain under 30 mph. This, combined with the heavy and wet nature of the snow, is not expected render impactful blowing snow. Things may change after the snow ends or as it is ending in south central and eastern North Dakota Saturday morning as northwest winds increase to around 25 mph with gusts to 35 mph through the afternoon. It is questionable how much snow will be blowable though. Our blowing snow model is highlighting just patchy to areas of blowing snow at this time, or in other words, only low to medium chances for blowing snow on its own reducing visibility below half a mile.

After the departure of the storm, a northwest flow pattern is favored through early next week, featuring a clipper passing by to the north and east on Sunday. A slight warm up to highs in the 40s is forecast for Sunday (though this could be impacted by the deep snowpack), followed by a cooler Monday on account of the aforementioned clipper. A more appreciable warm up could arrive by mid week before a more active looking pattern resumes.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 433 AM CDT Thu Apr 2 2026

IFR to LIFR ceilings at most terminals through this morning. Could see a brief improvement to MVFR in the western half of the state this afternoon before ceilings return to IFR/LIFR this evening.

Light snow remains possible at KJMS and surrounding areas this morning. Could see brief periods of IFR visibility, but mostly expecting MVFR to VFR. For the rest of western and central North Dakota, freezing mist or very light freezing drizzle could reduce visibility to MVFR/IFR this morning. And in southwest North Dakota, dense fog could develop early this morning.

Winds will remain easterly through the forecast period, with speeds around 10 kts this morning increasing to 15-20 kts this afternoon.

Near the end of the forecast period, a stronger storm system could begin impacting parts of western North Dakota with moderate to heavy snow.

BIS WATCHES/WARNINGS/ADVISORIES

Winter Storm Watch from this evening through Saturday afternoon for NDZ018>020-031>034-040>045. Winter Storm Watch from Friday morning through Saturday afternoon for NDZ021>023-025-035>037-046>048-050-051. Winter Weather Advisory until 7 PM CDT this evening for NDZ023- 025-036-037-046>048-050-051.