textproduct: Bismarck

KEY MESSAGES

- Low to medium chances (20-40%) for scattered showers and thunderstorms on Wednesday, then mainly dry Thursday through Saturday daytime. - Mainly seasonal temperatures this week, with above normal high temperatures on Thursday.

UPDATE

Issued at 1013 PM CDT Mon Aug 17 2026

Latest guidance continues to show various areas of convection possibly developing overnight. Thus, will continue to generally keep low precipitation chances in through the night over most locations. With that said, instability has waned back some, so think the severe threat has diminished, but cant rule out a little small hail or a modest wind gust over far southern portions of the area.

UPDATE Issued at 628 PM CDT Mon Aug 17 2026

Isolated thunderstorms continue over southern portions of our area as a short wave continues to swing around broad upper low centered over far southwest Hudson Bay. Additional short waves wrapping around the low continue to produce additional storms upstream in eastern Montana. So far the overall trend has been that some storms get a little strong for a bit, but have mainly remained sub-severe. With that said, instability and shear continue to be high enough for a storm to possibly become severe, mainly over our far southern areas. Therefore, will continue to monitor through the evening.

DISCUSSION

Issued at 250 PM CDT Mon Aug 17 2026

Currently, quasi-zonal/west-northwest flow aloft with a large area of upper level low pressure over Hudson Bay and an upper level ridge of high pressure extending from the Southern Rockies back north-northwest into the Intermountain West. Cold front situated roughly from southwest North Dakota northeast into the Northern Red River Valley. Embedded mid level impulses contributing to two areas of precip activity this afternoon. The first is over northwestern ND where scattered showers are moving into, and the second area is over southwestern ND along and ahead of the frontal boundary aided by left exit region jet dynamics aloft. There is enough effective wind shear (35-40 knots) for a few stronger/more organized updrafts over the past couple hours, with one severe storm firing up just across the border in northwest South Dakota. I opted to mention the entire far south in the HWO, with the Marginal (level 1 of 5) outlook near or over this area. Threat for severe weather should decrease with time as we lose daytime heating and as the front moves farther to the south.

Jet streak moving through aloft along with additional mid level impulses will maintain chances for showers and perhaps a few thunderstorms tonight across the local area. Threat for severe weather will be very low after peak heating as the more robust storms remain more to our south.

Surface high pressure builds into western and central North Dakota tonight into tomorrow, and will result in the weather trending dry, lowering dewpoint temperatures, and cooler temperatures mainly in the 70s to around 80.

Increasing return flow Tue night west as sfc high pressure slides off to the east, with models depicting a mid level wave also approaching Tue night through early Wed, resulting in the next chance for precipitation. Despite northwest flow aloft, temperatures will warm mid-week back into the 80s on Wednesday, then well into the 80s and lower 90s for Thursday as the aforementioned upper ridge broadens and nudges east (increasing southerly mid level flow). Mainly dry weather and seasonal temperatures to end the week as the upper ridge continues to develop east into the Great Plains. Ensembles then show the ridge breaking down later in the weekend into early next week, with shower and thunderstorm chances returning to the forecast and continued seasonal temperatures.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 628 PM CDT Mon Aug 17 2026

Isolated to widely scattered thunderstorms will continue to move through western and south central North Dakota this evening and overnight, clearing out Tuesday morning. Otherwise, VFR conditions are expected.

BIS WATCHES/WARNINGS/ADVISORIES

None.