textproduct: Bismarck

KEY MESSAGES

- Scattered showers and a few thunderstorms overnight, with daily chances for showers and thunderstorms continuing through Friday night. - A cooling trend is expected through Friday, followed by a warming trend through the weekend and into early next week.

UPDATE

Issued at 1216 AM CDT Thu Aug 13 2026

Showers and isolated thunderstorms continue across the north and the far south central into the James River Valley. Activity continues to wane slowly as Jet energy north and LLJ south also move away and dissipate. Made some minor adjustments to pops and sky cover. Otherwise no changes to the going forecast.

UPDATE Issued at 930 PM CDT Wed Aug 12 2026

Thunderstorm activity has greatly diminished across western and central North Dakota at the time of this mid to late evening update. Showers and a few isolated storms continue across generally along and south of I-94 to the east of Dickinson, with the greatest activity collocated with an axis of 300mb divergence across the far southern James River Valley into northeastern South Dakota at this time. A few more attempts at convection have occurred further to the north between Washburn and Jamestown, though with CIN rapidly increasing across the board and being displaced from the better forcing to the south, no much more than an isolated rumble of thunder or two has been forthcoming. In the northwest, the previously mentioned showers and storms in Montana have struggled to make their way into our west with the limited CAPE (generally less than 500 J/KG) becoming increasingly unbalanced with the strong Bulk Shear (around 50 to 55 knots) in that region. At least some thunder is expected to continue into the early overnight period, though coverage is expected to become increasingly limited. Further along the International Border, scattered moderate reflectivities have developed along the right entrance regions of a mid level jet dipping down out of Canada. A near nonexistent convective environment is expected to keep these as mainly showers, though again some isolated lightning is not impossible across portions of the north central through the early evening. With this update, have extended low PoPs further across north central North Dakota to account for the development of showers along this mid level jet, and to account for the latest model trends. Otherwise, the forecast remains in good shape this evening.

UPDATE Issued at 700 PM CDT Wed Aug 12 2026

Showers and thunderstorms have lifted into portions of western and south central North Dakota by the time of this early evening update. A fairly marginal and unbalanced convective environment is found over the forecast area, with mesoanalysis revealing somewhat modest MUCAPE values around 500 to 1250 J/KG, but fairly strong 0-6KM Bulk Shear values around 45 to 55 knots across along and south of Highway 200. The convective environment remains the best across the south central, where a strong to severe storms have developed over the course of the last few hours. Here, the highest mid level lapse rates of 6.0-6.5 C/KM have been more supportive of large hail production, and fairly straight low level hodographs have allowed for the occasional, short- lived left-split super cell (which are usually more prolific hail producers). With conditions further east starting to become worked over by earlier showers and storms, and where the convective has already been more marginal throughout the evening, more disorganized, clustered storms have been found. Cell mergers between these storms or interactions with a few outflow boundaries moving to the northwest have allowed a few stronger storms to develop, though even these have been fairly short lived. Upstream in Montana, another round of showers and storms are slowly making their way toward out western border, arriving some time within the next two hours or so. Have tweaked PoPs, winds, and sky cover with this update to account for the latest radar, model, and satellite trends.

DISCUSSION

Issued at 225 PM CDT Wed Aug 12 2026

Currently near zonal flow exist over the Northern Plains with a slight southwest tilt over Montana. A trough and upper low digs through Washington state at this time. At the surface a low sits in eastern Wyoming with an inverted trough through eastern Montana with showers and thunderstorms around the low.

Today we are in another severe risk, this time just a level 1 across the southern half of the state. Global models have 1000 to 2000 J/kg of MUCAPE with 45 to 50kts of shear. The actual 18z sounding from Bismarck shows 1900 J/kg of CAPE from the surface with very little CIN and 53 kts of shear. Hazards today could be golf ball size hail with all that shear and 60 mph winds. So far very light rain from the low pressure is in the southwest with thunderstorms in southeast Montana. A few failing storms are trying in south central North Dakota. The forcing and indicator for where the severe storms will be is the right entrance region of the jet streak. Currently that area is over southeastern Montana, entering into southwest North Dakota. Looking at radar new storms are quickly growing in southeast Montana. That jet streak is forecast to move east with the right entrance region staying along the South Dakota border. After 00z, models want to pull most of the CAPE out of the state and into eastern South Dakota as the surface low moves east. After this evening showers and maybe a thunderstorm are possible through the night.

The rest of this week the flow will turn southwest and the trough continuing to dig into the west CONUS. This, in turn, will produce daily chances of showers and thunderstorms through Friday night, with the highest chances across the west everyday. Temperatures will continue to remain at or below normal in the 70s and lower 80s through Saturday. Slight northwest flow returns this weekend with a slight ridge to start next week. Therefore normal temperatures in the 80s will return.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1216 AM CDT Thu Aug 13 2026

Mainly VFR conditions expected to begin the 06Z TAF period. However, KDIK was reporting some fog. Low stratus and fog will be possible across the area overnight and into Thursday morning, especially in the southwest and south central. Included a period of IFR-LIFR cigs/vsbys at KDIK around 12 UTC. Isolated showers and thunderstorms continue to track across northern ND including KXWA and KDIK. Have included a VCSH for KXWA and a VCTS for KMOT. After the overnight shower activity most areas should remain dry on Thursday but will see increasing chances for showers at KXWA, especially after 00Z Friday, with areas of MVFR ceilings after 00Z as well.

BIS WATCHES/WARNINGS/ADVISORIES

None.