textproduct: Bismarck

KEY MESSAGES

- Low to medium chances (20 to 50 percent) for thunderstorms late this afternoon through tonight. Isolated to scattered severe storms are possible, mainly in the south.

- Showers and thunderstorms could return again Wednesday. Isolated severe storms are possible in the south. - Near average temperatures today, with a cooling trend then expected through Friday, followed by a warming trend through the weekend and into early next week.

UPDATE

Issued at 940 AM CDT Tue Aug 11 2026

Isolated to scattered thunderstorms have formed between Highway 83 and Jamestown. The current Severe Thunderstorm warning will be allowed to expire at 945 since the storm is no longer intense. We are still in a level 2 risk today. If you believe the CAMs no storms will happen before sunset, although the current storms are on none of the CAMs so we will continue to monitor that.

UPDATE Issued at 612 AM CDT Tue Aug 11 2026

Isolated showers may skirt the far southwest early this morning. Also an isolated shower recently developed over central Kidder county. Adjusted pops to account for these areas. Also adjusted sky cover with quite a bit of low VFR and pockets of MVFR ceilings developing over the southern half of the state. Updated text products will be transmitted shortly.

DISCUSSION

Issued at 410 AM CDT Tue Aug 11 2026

A near zonal to slightly northwest upper level flow remains over the area today and Wednesday, followed by a transition to a broad southwest upper level flow through the end of the work week.

Currently, late evening into early overnight convection has ended over the area. A few showers were noted over southeast Montana, otherwise skies were clear to partly cloudy. Low VFR to MVFR ceilings have been developing over the past couple of hours across central and into northeast ND. RAP forecast 925-850mb RH indicates higher RH remaining along and south of the I-94 corridor through the morning and possibly into early afternoon. As of yet there is little indication of any fog, but the potential will remain through mid-morning.

This afternoon will bring another chance of thunderstorms to western and central ND. In general, most guidance develops convection in the late afternoon (after 21 UTC) over southwest ND and tracks it southeast through the evening. There are some CAMS that extend convection farther north into northwest and north central ND, and others indicate late afternoon into evening convection, followed by another round of overnight convection, possibly lingering into Wednesday morning.

Strong (40-60kts) bulk shear will be over the forecast area through the period. The greatest instability will be in the southwest this afternoon into early this evening. The RAP does indicate some elevated instability remaining over western ND late tonight with a weak inverted trough near the Montana border. Thus the probability of a couple rounds of convection can not be ruled out. However, there isn't much of a llj overnight tonight which would help to maintain any late night convection. The higher probability for strong to severe storms looks to be late afternoon into this evening in the southwest and south central. With the strong shear and supercell wind profiles, we will keep the previous hazards of golf ball sized hail and 70 mph winds. As there was earlier this evening, there will be the potential for splitting cells again today.

A similar setup on Wednesday will take place with the greatest instability by afternoon in southwest/south central portion of the state. Strong shear remains over the area so any storms that would be able to develop sustain themselves, would have the potential to become severe. SPC currently has a marginal risk for severe storms along and south of the I-94 corridor. Currently, the instability does not look to be as strong Wednesday so for the time being, will keep main hazards of quarter size hail and 60 mph winds.

Later in the workweek, we transition to more of a broad southwest upper flow with a series of waves moving through the mean flow. With cooler temperatures in store Thursday and Friday, instability will remain low, thus we expect more showers and isolated thunderstorms with a low threat for severe storms.

After Friday we begin a slow warm-up back to near normal temperatures through the weekend and into early next week. Westerlies remain over the area so we would expect a continuation of the near daily chances for thunderstorms, rather than a big warmup with dry conditions.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 612 AM CDT Tue Aug 11 2026

Low VFR to MVFR ceilings continue to develop over the southern half of the state. Most ceilings were VFR but MVFR ceilings at KBIS to begin the 12Z TAF period. Potential for MVFR ceilings at the southern TAF sites through this morning, but attim, only mention of MVFR ceilings was at KBIS. Variable but mainly easterly winds through the TAF period. Thunderstorms are possible late this afternoon and tonight at all TAF sites with gusty and erratic winds and MVFR ceilings/vsbys possible with any thunderstorms that do develop.

BIS WATCHES/WARNINGS/ADVISORIES

None.