textproduct: Bismarck

KEY MESSAGES

- Temperatures remain below normal through the rest of the week (normal highs around 50F), with forecast highs mainly in the 30s.

- Dry conditions today, followed by the first round of accumulating snow in the south (60 to 80%) late tonight through Thursday, with chances (25 to 50%) north.

- Increasing confidence for widespread accumulating snow (possibly moderate to heavy) Thursday night through Saturday across the region. Lower confidence regarding the placement of heavier precipitation and amounts.

DISCUSSION

Issued at 348 PM CDT Tue Mar 31 2026

This afternoon, zonal flow aloft was in place over the forecast area, with cool surface high pressure centered in southeast Saskatchewan. A modest surface pressure gradient has been in place all day, with breezy winds becoming more northerly as the high passes to our north. Some low clouds are still hanging around across the north and east, and temperatures are seasonably cool, with afternoon highs in the upper 20s north to lower 40s south.

The main forecast highlight of this week is two rounds of accumulating snow, favored across southern North Dakota. The first round of snow is progged to begin overnight tonight as a surface low tracks into South Dakota, while flow aloft turns more southwesterly in response to a shortwave digging over the Rockies. Snow then expands to the north and east through the day Wednesday, continuing into Thursday before shifting off to the east of the forecast area.

We have issued a Winter Weather Advisory for parts of southwest and all of south central North Dakota, including the James River Valley. The western segment starts late tonight while the eastern segment starts Wednesday morning, continuing through Wednesday and much of Thursday. It is likely that there will be a break in precipitation at some point during the day Wednesday, as the initial wave lifts off before the main low deepens and the precipitation field becomes more widespread. 12Z HREF and some recent deterministic guidance is starting to advertise some potential for reaching the 6 inch threshold in our far south central and southeast. However, with it being a longer-duration event with generally light snow rates, thinking this is more of an advisory level event, although cannot rule out isolated spots hitting that 6 inch threshold. The lower snow rates and the duration could end up somewhat impacting event totals, from a combination of being slow to start accumulating and some compaction, as snow ratios will be near normal (10:1). Latest NBM puts the 6 inch probability generally around 20 percent or less, which fits the overall synoptic set up and no noticeable significant forcing. The expectation is for a general 2 to 5 inches of snow from Dickinson, to Washburn, to Carrington, and south, with slightly higher amounts in the Linton to Oakes area. With the surface low far enough away, current forecast has breezy winds but not overly strong compared to what we can sometimes see with winter systems. We do have mention of patchy blowing snow in the gridded forecast and will likely have reduced visibility as snow is falling, but with the snow ratios not as confident in how widespread blowing snow problems will be after snow has settled.

Snow will taper off sometime later in the day on Thursday, but this break will be short-lived. A more pronounced trough and closed low is projected to deepen over the Pacific Northwest on Thursday before ejecting into the Central Plains on Friday. The general expectation is for the surface low to stay well to our south, while the upper low tracks somewhere over the Dakotas and into Minnesota. The latest NBM 5.0 48-hour probabilities show a 50/50 shot for at least 4 inches of snow in a line from Slope to Wells Counties and for areas south, with low probabilities of exceeding 8 inches of snow across this area with the exception of the far south central and parts of the James River Valley where there are medium chances for this threshold. It is worth noting a low but non-zero likelihood for a foot of snow in the southern James River Valley area, so would have this as a reasonable worst case scenario (90th percentile).

Recent ensemble runs have trended the surface low a bit more towards the northwest on Saturday, which will be something to keep an eye on. NBM wind forecast has trended up in response in the James River Valley, although this signal is not showing up in the ECMWF EFI just yet. Blended guidance kicks the low out later on Saturday and POPs drop off similarly.

Temperatures will be relatively consistent Wednesday through Saturday under the influence of these two systems, with highs mainly in the 30s. We start to see more notable changes on Sunday as flow aloft turns northwesterly in the wake of the late week trough, although NBM temperature percentiles are uncertain in how warm highs could get by midweek.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1250 PM CDT Tue Mar 31 2026

Scattered MVFR ceilings are persistent across northern and eastern North Dakota to start the TAF period, and although dissipating, low confidence on when exactly conditions will fully return to VFR this evening. Breezy northerly winds will diminish tonight, shifting to be more southeasterly and increasing late tonight into Wednesday morning as our next system moves in. Expect widespread MVFR to IFR ceilings by the end of the TAF period, with periods of prevailing snow at southern terminals KDIK and KBIS, and PROB30 groups included at other terminals.

BIS WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory from 1 AM CDT /midnight MDT/ Wednesday to 1 PM CDT /noon MDT/ Thursday for NDZ018>020-033-034-041-042- 044-045. Winter Weather Advisory from 7 AM Wednesday to 7 PM CDT Thursday for NDZ021>023-025-035>037-046>048-050-051.