textproduct: Bismarck

KEY MESSAGES

- Isolated to scattered severe thunderstorms are expected this evening, especially in central and eastern North Dakota. Hazards include hail up to 2 inches in diameter and wind gusts up to 70 mph, with an isolated tornado threat.

- A gradual warming trend is expected through Friday, with above average highs favored. A cooling trend back to near average highs is then favored for the holiday weekend.

- Scattered showers and thunderstorms are possible as early as Thursday, lasting through the holiday weekend.

MESOSCALE

Issued at 600 PM CDT Mon Jun 29 2026

The threat for severe thunderstorms continues across the Tornado Watch. The greatest risk for tornadoes is in the warm/moist sector of a quasi-stationary surface trough over central North Dakota where surface winds are easterly to southerly, mainly along and east of Highway 83 from Minot southward. Convective coverage along and south of Highway 200 has remained dampened, but an increase in synoptic scale forcing is expected over this area during the early evening. This forcing is currently being ejected from the base of the upper level low, and has initiated deep, moist convection in southwest North Dakota near Hettinger. The tornado threat there is much lower, but there does appear to be a subtle low level wind convergence there that could locally enhance low level shear. However, it is more likely that this convection, as well as what is upstream in eastern Montana, is elevated.

In a bigger-picture sense, the atmosphere remains strongly primed for severe weather, with very strong to extreme effective bulk shear around 55-65 kts across all but far northwest North Dakota, and MLCAPE around 2500-3500 J/kg with little to no MLCIN east of the aforementioned surface trough. Very large hail remains possible with any discrete storm. Damaging winds could occur with any storm mode, but is much less favorable north of Highway 2 where DCAPE is analyzed to be well under 1000 J/kg. To reiterate, we do anticipate an increase in convective coverage across southern North Dakota between 6 and 8 PM CDT, in line with recent HRRR trends.

Another recently emerging hazard is flash flooding over north central North Dakota where training storms in and anomalously high precipitable water environment are producing hourly rainfall rates and total amounts in excess of 3 inches.

DISCUSSION

Issued at 104 PM CDT Mon Jun 29 2026

An impressive upper level trough sat over Montana and Wyoming early this afternoon with a jet rounding the base into the northern high plains. A surface low is centered over the central to eastern Dakotas, which will lift northeast as the upper jet continues to eject out over the plains through the evening. A lower level moisture gradient is a highlight of today's setup with 17Z surface dew points sitting at around 70 degrees in the warm sector, mainly near and east of a line that cuts north- south through the state (roughly going through Bismarck and just east of Minot). West of this line low level moisture is notably lower with a few non-severe thunderstorms rolling through this morning.

Scattered convection is expected to redevelop this afternoon under the influence of the ejecting upper jet/trough. This incoming jet aloft will provide strong shear in the 50-60kt range with the warm sector's rich moisture bringing a conditional opportunity for adequate instability for severe weather. Early morning convection made the instability potential somewhat uncertain, though satellite trends at 17Z show pockets of clearing which should allow for an increasing trend in surface based instability. Supercells with the threat of very large hail and damaging wind gusts will be the primary threat, at least initially until some clustering and upscale growth likely occurs. A tornado threat will also accompany thunderstorms, especially towards the eastern portions of the state. The intensity of the overall wind shear cannot be understated and will allow for any storm that can tap into richer low level moisture to produce hail exceeding 2 inches in diameter or wind gusts exceeding 70 mph. As mentioned before the coverage may partially depend on how well earlier stratus can clear, with lingering clouds preventing full destabilization.

Several rounds of severe convection will be possible as the upper level trough swings through late this evening. The thunderstorm threat will likely linger longest across the far north before exiting around or just after midnight.

On Tuesday the upper low will be well over the southern Canadian plains with drier westerly flow across North Dakota. Windy west winds of 20-30 mph with gusts up to 45 mph will be common with highs from the mid 70s northwest to mid 80s far southeast.

Flow on Wednesday remains westerly, though less windy than Tuesday. There is rising confidence among deterministic and machine learning guidance in convection and severe weather potential returning as early as Thursday, though where the strongest storms set up in the state is still dependent on uncertain moisture return.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 628 PM CDT Mon Jun 29 2026

Showers and thunderstorms will lift across the area through this evening. A few severe thunderstorms are possible. Expect MVFR to brief IFR conditions with any thunderstorms. Showers and thunderstorms diminish tonight. Some MVFR to low VFR ceilings may linger this evening into the early overnight hours, with VFR conditions returning by late tonight. VFR conditions continue for Tuesday. Some showers and thunderstorms are possible north of US Highway 2 with confidence to low to include in any TAF sites at this time. Variable winds will be found this evening, becoming a westerly wind tonight. Breezy westerly winds will then be found for Tuesday.

BIS WATCHES/WARNINGS/ADVISORIES

None.