textproduct: Bismarck

KEY MESSAGES

- Isolated to scattered severe thunderstorms could develop in central and eastern North Dakota this afternoon and evening. There are higher chances for storms developing in eastern North Dakota than central.

- Potential hazards from severe storms this afternoon and evening include large hail up to 2 inches in diameter and damaging winds up to 70 mph, with a tornado possible in the James River Valley early this evening.

- Near-critical fire weather conditions are expected across much of western North Dakota this afternoon and early evening, and could return to far southwest parts of the state on Tuesday.

- A little warmer today, then cooler and windy on Tuesday. Near to slightly above average temperatures are favored from the middle of the week through the weekend.

UPDATE

Issued at 645 AM CDT Mon Aug 24 2026

Widely scattered showers and thunderstorms continue to move through the state this morning, with concentrated areas between Garrison and Minot, Rolla and Rugby, and Carrington and Cooperstown as of 645 AM CDT. The risk for severe weather is very low for the rest of the morning.

DISCUSSION

Issued at 520 AM CDT Mon Aug 24 2026

A deep upper low is spinning from southern Alberta into southern Saskatchewan early this morning, with an attendant surface trough extending from the surface low over central Saskatchewan through western North Dakota. A preceding lower- amplitude shortwave is traveling along the North Dakota- Manitoba border and has been responsible for thunderstorms producing excessive rainfall, especially from around Bottineau to Rugby. Ground-truth rain amounts around 4 inches have been reported, and MRMS is estimating near 6 inches locally. As of 5 AM CDT, the threat for torrential rainfall has exited our forecast area. Farther upstream, isolated showers and storms that are likely being maintained by a plume of low level warm air advection are moving from northwest into north central North Dakota. These have mostly been benign and were beginning to rapidly diminish as of 5 AM CDT, but earlier in the night there was a rogue 58 mph wind gust at an NDAWN station near Ray. The magnitude of warm air advection is forecast to decrease later this morning, which could allow this activity to continue to dissipate. A few CAMs hint at redevelopment of weak elevated convection in northwest North Dakota later this morning, likely in response to height falls from the Saskatchewan low, but more recent CAMs have backed off on this potential.

Still looking at a conditional threat for severe thunderstorms in central and eastern North Dakota along and ahead of the eastward advancing surface trough this afternoon and evening, with uncertainty rooted in whether there will be strong enough forcing to overcome CIN. The most recent suite of CAMs is more confident that convective initiation will occur at some point and time, but it may not be until closer to early evening when the frontal boundary reaches the James River Valley. The SPC has introduced a Slight Risk (level 2 out of 5) to the eastern third of the state, reaching as far west as the James River Valley. A discrete storm mode is favored, but splitting supercells/storm mergers could contribute to upscale growth and/or clustering of storms. CAPE in the 2000-3000 J/kg range and deep layer shear around 35-40 kts will be supportive of very large hail to around 2 inches in diameter. The amount of shear and high forecast DCAPE also leaves our most likely maximum wind gust forecast at 70 mph. Did elect to begin messaging a possible tornado, which would most likely be limited to the James River Valley in the early evening when and where the combination of stronger low level shear/SRH and weaker MLCIN is maximized.

Today will be seasonably warm, with highs in the lower 80s to lower 90s. A much drier air mass and gusty west-northwest winds behind the surface trough will create near-critical fire weather conditions this afternoon and early evening, especially from near Williston to Bowman. The Canadian low will spin into southern Manitoba on Tuesday before diving southeast toward the western Great Lakes. This will leave cooler temperatures and windy conditions over the Northern Plains on Tuesday, with highs in the mid 70s to lower 80s and northwest winds around 20 to 30 mph, gusting as high as 40 mph. RH may fall low enough in the far southwest for another afternoon of near-critical fire weather conditions on Tuesday. There could also be some diurnally-driven afternoon showers in the cyclonic flow regime on Tuesday. The NBM limits this potential to the Turtle Mountains, but some runs of the HRRR have brought isolated showers as far south as the northern James River Valley.

Broad surface high pressure is forecast over the region on Wednesday as the upper level ridge re-amplifies over the Rockies. Guidance then favors the ridge axis being shoved eastward on Thursday as a deeper trough digs into the Pacific Northwest. Shortwave energy ejecting from the base of that trough brings shower and thunderstorm chances back to the region as early as Thursday night, with near-daily low to medium chances continuing through the weekend as a more progressive synoptic pattern emerges. Temperatures are favored to remain near average overall, but could trend slightly above average closer to the end of the week.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 645 AM CDT Mon Aug 24 2026

A few showers and thunderstorms remain possible across northern, central, and eastern North Dakota this morning. Later this afternoon and evening, isolated to scattered severe thunderstorms producing large hail and damaging winds could develop in the eastern half of the state. A PROB30 mention for a severe storm has been added to the KJMS TAF this evening. Outside of showers and thunderstorms, VFR conditions are expected through the forecast period. Winds will become west to northwest in western North Dakota this afternoon around 15-20 kts, with gusts to around 30 kts in the northwest. Central North Dakota should see southerly to westerly winds remain closer to 10 kts through the day.

BIS WATCHES/WARNINGS/ADVISORIES

None.