textproduct: Bismarck

KEY MESSAGES

- Seasonable temperatures are favored through the weekend, with highs mostly in the 60s and 70s and lows in the 40s and 50s.

- Medium to high chances for showers and a few thunderstorms on Wednesday. Then, low to medium chances for mainly showers on Friday.

UPDATE

Issued at 905 PM CDT Tue Sep 22 2026

Low stratus continues to spread across the state filling in across the south central. No major updates are needed at this time as the forecast remains on track.

UPDATE Issued at 622 PM CDT Tue Sep 22 2026

Low stratus continues across the region with a small gap in the south central that will fill in. The northwest remains clear at this time but low stratus will push up into the area. Stratus will lower tonight ahead of a system moving through the region. No major updates are needed at this time as the forecast remains on track.

DISCUSSION

Issued at 235 PM CDT Tue Sep 22 2026

A somewhat chaotic flow pattern is found over the northern Plains this afternoon as a developing ridge to the west of the forecast butts up against an exiting upper level low exiting into the Great Lakes Region. Increasingly cloudy skies are expected through the afternoon and evening as moisture returns from the Gulf increase across the state. Highs today will thus be warmest in the upper 60s to lower 70s across the northwest and north central where partly cloudy to mostly clear skies linger the longest, while the southwest and south central will only peak into the lower to mid 60s. Breezy south to southeasterly winds, with sustained speeds up to around 25 MPH and gusts up to 35 MPH, will be found as a modest pressure gradient is draped across the northern Plains and will linger overnight into early Wednesday. Otherwise, the increasing cloud cover and persistant southerly surface flow are expected to keep low temperatures tonight mainly in the mid 40s to lower 50s.

Upper level flow over the northern Plains is then expected to consolidate and turn increasingly southwesterly late tonight into early Wednesday as a shortwave perturbation passes through the area. Along with the increasing moisture across the area, this wave will promote medium to high (50 to 80 percent) chances for showers across western and central North Dakota starting Wednesday morning, with isolated thunderstorms also possible (20 to 30 percent) Wednesday afternoon and evening. While the initial convective environment is expected to be fairly tame, with MUCAPE values peaking only around 500-750 J/KG above the prevailing cloud layer and cooler surface temperatures, there is some potential for an isolated stronger storm over the southwest into the south central late Wednesday afternoon into Wednesday evening as a weak cold front/surface trough is pulled across the area. The overall potential for hazards remains low, with sub severe winds and maybe some small expected with any stronger storm that does develop. Storm total rain through late Wednesday are anticipated to be light, with amounts generally from around 0.10" across the west up to around 0.25" to 0.75" central. While the current calibrated NBM chance to exceed 1.00" is low through this period, around 15 to 35 percent across portions of the northern James River Valley, high model PWATs around 1.25" indicate that locally higher totals can be anticipated where and when thunderstorms develop. Otherwise, for Wednesday, highs in the 60s to lower 70s can be anticipated as prevailing clouds and showers limit diurnal heating potential.

For the end of the workweek, the amplification of a transient upper level ridge across the northern Plains on Thursday will promote clearing skies, dry weather, and warmer temperatures in the lower 70s and 80s. Then, heading into Friday, low to medium chances (30 to 50 percent) for showers will pass across much of western and central North Dakota as another shortwave perturbation ejects off of the western Rockies and passes north across the forecast area. The overall potential for thunderstorms appears to be fairly limited through the day on Friday, with ensemble members advertising the better convective environment further to the south and east of the forecast area. While it wouldn't be overly surprising to see a rumble of thunder or two in the far southern James River Valley, mainly showers can be anticipated at this time. Overall QPF is also expected to be fairly limited, with the calibrated NBM 5.0 probability for more than 0.25" of rain fairly low (20 to 40 percent). Otherwise for Friday, the increased cloud cover associated with the showers will help put a damper on the above normal temperatures previously forecast in earlier cycles, with highs now expected to range in the mid 60s to mid 70s.

Looking ahead, the weekend is going to be characterized the passage of a strong pacific trough/closed low across the Canadian Prairies. Mainly dry and warm (highs in the 60s and 70s) conditions are expected as flow over the northern Plains turns southwesterly on the leading edge of the trough. The prevailing southeasterly winds over turn northwesterly on Saturday as a cold front is lofted through the area, though poor saturation throughout the vertical profile will limit overall chances for precipitation. The ensemble continues to delay the onset precipitation over the Dakotas compared to previous forecast cycles, due to the slightly slower evolution of this trough. There is fairly strong agreement between ensemble members for showers some time Monday through the early workweek, though there is a hint in some clusters (approx 30 percent of members) of a more divergent flow pattern over the northern Plains. In this particular scenario, much of the forecast area would struggle to see much measurable precpitation.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 622 PM CDT Tue Sep 22 2026

Low stratus is forecast to lower in the next few hours brining back MVFR conditions. KXWA will remain clear for a few hours before stratus pushes back up into the northwest. Winds will remain elevated out of the southeast tonight around 10 to 15 kts. A system will move into the area tomorrow morning which will bring rain chances to much of the terminals. There could be IFR conditions in the early morning due to lowering stratus and falling rain.

BIS WATCHES/WARNINGS/ADVISORIES

None.