textproduct: Bismarck

KEY MESSAGES

- Low chances (20-30%) for thunderstorms southwest this afternoon into early this evening. A strong to marginally severe storm can not be ruled out, but widespread severe storms are not anticipated.

- Low to medium chances (20-50%) for showers and isolated thunderstorms tonight. Severe storms are not expected.

- Near daily low to medium chances (20-50%) for hit and miss showers and thunderstorms through the work week. - Seasonable temperatures are expected today and through the upcoming work week.

DISCUSSION

Issued at 357 AM CDT Sun Aug 16 2026

A northwest upper level flow will remain over the forecast area today and through the upcoming work week. Currently, a broad upper lever ridge was located over the western U.S. Numerous shortwaves were propagating through the ridge, with a couple tracking through the Northern Rockies. Another shortwave was tracking through the western Canadian Provinces, and finally, a strong wave was dropping southeast through northern Canada around a developing Hudson Bay Low.

The initial shortwave energy may spark isolated to scattered thunderstorms over western ND this afternoon. The southwest will become moderately unstable with SB Capes around 1000-1500 J/kg. Bulk shear, initially modest does increase late this afternoon into this evening with 30 to 40kts of shear over the area. A couple of forecast soundings in the far southwest indicate a marginally severe to severe atmosphere may be possible. The main issue may be timing of shortwave energy lining up with peak instability. Both are present, but if they don't line up well, strong convection may not occur. A look at the latest CAMs shows most do develop some convection over/near the southwest late this afternoon into early this evening. A few do show stronger updrafts, while others are pretty weak. The main hazard would be small hail. Will continue to monitor, but at this time will not mention severe storms. Better chances for strong to severe storms remains over western South Dakota.

Later tonight the aforementioned western Canadian wave and it's attendant surface low, tracks across the southern Canadian Prairie Provinces. Its surface warm front, which was lingering over eastern Montana, and its quickly following cold front tracks east across the forecast area tonight. So we have the early convection in the southwest, then later convection tracking northeast to southwest across the forecast area. By the time the northern convection makes it into the state, instability will be minimal and strong to severe storms are not anticipated. There may not be that much in the way of convection at all, with scattered showers and maybe some isolated thunderstorms.

Finally, the northern Canadian shortwave diving south, catches up with the leading cyclone over southeast North Dakota by Monday afternoon. Convection tracking through the area late tonight may linger over the south central and into eastern ND on Monday morning. By the time the northern front catches up and helps to invigorate convection over eastern ND, it is forecast to be out of our neck of the woods.

Thus after all this, some stronger convection can not be ruled out later this afternoon into early this evening over the southwest. Later this evening and overnight, additional isolated to scattered showers track southeast across the forecast area, and may linger into Monday morning in the south central and James River Valley. If convection does re-invigorate Monday, it looks like the potential for severe storms will be southeast of the forecast area.

We cool down on Tuesday behind the Canadian cold front with highs mainly in the 70s. We then see a warm-up with highs mainly in the 80s by Thursday, then mid 70s to mid 80s into the weekend. With the northwest upper flow remaining over the area, daily hit and miss thunderstorms chances will remain in the forecast but with low predictability in timing and placement.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1155 PM CDT Sat Aug 15 2026

VFR conditions to begin the 06Z TAF period and mainly VFR conditions expected through the forecast period. With high pressure over the forecast area Sunday morning, light winds and mostly clear skies are expected. Patchy fog will be a possibility across the area. Guidance is not indicating much for fog at this time so confidence is too low to add to any TAF site. There will be a low chance for thunderstorms in the southwest this afternoon, then tonight, low chances (20-30%) for showers and thunderstorms track east across the forecast area. At this time, may add a PROB30 to western TAF sites, but again, confidence is too low for anything more at this time. Light surface flow tonight. During the day Sunday expect winds generally 12kts or less from the northwest over central and from the south over western ND.

BIS WATCHES/WARNINGS/ADVISORIES

None.