textproduct: Bismarck

KEY MESSAGES

- Temperatures will become very hot again over the weekend, with highs near 100 in western North Dakota on Saturday and central North Dakota on Sunday.

- It will be windy on Sunday, with near-critical fire weather conditions expected across much of the western half of the state.

- The first half of the upcoming work week should be much cooler, with highs in the 70s and 80s.

- Low to medium chances for showers and thunderstorms late Sunday night through Monday. A few storms could be severe in central and eastern parts of the state.

UPDATE

Issued at 652 AM CDT Fri Jul 31 2026

Satellite imagery and surface webcams show valley fog throughout the Badlands surrounding the South Unit of Theodore Roosevelt National Park. The fog is reducing visibility along I-94 in Billings County, but does not appear to be impacting travel elsewhere. Patchy ground fog has also developed across the rest of western and central North Dakota wherever skies are clear. This fog should mostly be unimpactful, although visibility has recently fallen below a quarter mile at the Rolla AWOS.

DISCUSSION

Issued at 451 AM CDT Fri Jul 31 2026

A shortwave trough is located over the eastern Dakotas/Minnesota early this morning. The associated surface low is analyzed near Sioux Falls, with a broad high pressure ridge from northern Saskatchewan through western North Dakota. Shower and thunderstorm activity has shifted well off to the southeast. Patchy fog remains possible along the surface ridge axis in western North Dakota early this morning, but little to none has been observed as of this writing. The surface ridge is forecast to slide into central North Dakota this afternoon as the downstream shortwave digs southeastward along the lower Missouri River Valley. There is a low-amplitude shortwave traveling along the top of the upper level ridge over central Montana early this morning that is responsible for showers and isolated thunderstorms. Models tend to dissolve and slow the progression of this shortwave as it approaches western North Dakota, but it appears to be more potent and progressive on water vapor imagery. There is a low chance that this wave could bring a few showers or thunderstorms to western parts of the state today, but the forcing will be running into rising mid level height tendencies, as well as the surface ridge. Only a narrow ribbon of no greater than 1000 J/kg CAPE is forecast across far western North Dakota through this evening, and model soundings would indicate mid level capping should prevent convection from becoming surface or mixed-layer based. If an updraft were to become rooted in the boundary layer, it would experience effective bulk shear around 35-40 kts. The 00Z HREF does still have a contour of 10 percent in its neighborhood probability of updraft helicity exceeding 75 m^2/s^2, but almost the entire contribution to that appears to be from 12Z initialized members. It is therefore highly unlikely that there will be any stronger storms today, although inverted-v thermodynamic profiles could support gusty winds with even just showers. But the probability of any showers or storms in western North Dakota today remains under 20 percent. Those chances do increase slightly and shift into north central North Dakota tonight as the low level jet increases and turns to point northeastward, inducing warm air advection. But any overnight activity would likely be limited to just showers as forecast CAPE over north central North Dakota tonight remains very low.

With North Dakota sitting between a downstream trough and upstream ridge today, high temperatures are forecast to be limited to the lower and mid 80s east but reach the lower 90s west. Over the course of the weekend, the upper ridge will once again become highly amplified and pivot into a positive tilt as a potent upper low digs into British Columbia. The thermal ridge expands into western North Dakota on Saturday where highs could approach 100, then gets shoved over central North Dakota on Sunday as the British Columbia low ejects into the Canadian prairie and drives a cold front into western North Dakota. Recent NBM guidance has trended slightly cooler with temperatures both days this weekend, with daily maxima projections now closer to 100 rather than 105. But still think compressional heating ahead of the cold front could produce a corridor of ~105 degree Fahrenheit temperatures over south central North Dakota Sunday afternoon. We will continue to message heat concerns this weekend, but the latest trends paired with it being a drier air mass may preclude the need for any headlines. The other concern for Sunday is that windy conditions both ahead of the front (south winds around 25 mph gusting to 40 mph) and behind the front (northwest around 20 mph gusting to 30 mph) will combine with the hot and dry air to produce at least near-critical fire weather conditions across much of the western half of the state. The current forecast calls for only around 1 to 3 hours of meeting Red Flag criteria, and only on a limited basis spatially. But the wind shift with the frontal passage and very hot temperatures are factors that will need to be considered. As it stands now, there is still enough uncertainty in the magnitude of winds and the timing of the cold front to preclude the issuance of a Fire Weather Watch, but this could easily change with future forecast updates.

The cold front is forecast to temporarily stall from northeast to south central North Dakota Sunday night into Monday as the Canadian low occludes and a separate shortwave lands on the American side of the Pacific Northwest. The cold front itself is unlikely to be able to initiate convection during the day Sunday as it moves through a high CIN and low RH environment, but some sets of model guidance introduce QPF late Monday night as stronger mid level height falls commence over the region and flow aloft turns southwesterly with embedded shortwave energy. Effective bulk shear can be tricky to forecast for elevated convection days in advance, but an example sounding (NAM at Carrington) does show a lengthening of the hodograph above 3 km AGL with time Sunday night into Monday morning, and that same sounding calculates MUCAPE as high as 1500 J/kg. Monday afternoon may provide a more favorable opportunity for severe convection in a highly-sheared environment, but whether that impacts our forecast area will depend on the eastward progression of the cold front. The SPC has introduced a Day 3 Marginal Risk across central North Dakota for overnight elevated convection and the off chance a surface-based storm can develop in the late afternoon/early evening (but as alluded to above, the latter has a very low probability of occurrence).

The cold front will finally bring relief from what has been one of the hottest Julys on record. Forecast highs on Monday still reach the mid 80s near the stalled frontal boundary in south central North Dakota, but are limited to the mid and even lower 70s in the far northwest. Gusty north to northwest winds are also in the forecast for Monday, which could prolong fire weather concerns in southwest parts of the state where afternoon RH is still forecast to fall near 20 percent despite the cooler temperatures. The NBM favors Tuesday to be the coolest day, with forecast highs now no warmer than the upper 70s. The evolution of the synoptic pattern from mid to late next week remains uncertain. Higher-membership ensemble clusters want to transition to a northwest flow pattern as the upper ridge rebuilds over the Rockies, while lower-membership clusters tend to maintain broad troughing or quasi-zonal flow over the Northern Plains.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 652 AM CDT Fri Jul 31 2026

Patchy fog is possible across much of western and central North Dakota early this morning, but TAF sites are not expected to have prevailing categorical visibility restrictions. VFR conditions are otherwise expected through the forecast period. Winds today will be south-southeast around 10-15 kts from KXWA to KDIK, light and variable from KMOT to KBIS, and north- northeast around 10 kts at KJMS.

BIS WATCHES/WARNINGS/ADVISORIES

None.