textproduct: Bismarck

KEY MESSAGES

- Very hot conditions through the weekend, with dangerously high temperatures and heat index values around 100 to 105 degrees.

- Smoke from distant wildfires will make skies hazy and may reduce surface visibility today.

- The combination of hot, dry, and breezy conditions on Sunday may cause near-critical fire weather conditions in parts of western and central North Dakota.

UPDATE

Issued at 1215 PM CDT Sat Jul 25 2026

Fog has dissipated across the south central and into the James River Valley. Very hot temperatures are the main hazard this afternoon. The Heat Advisory goes into effect at 1 PM CDT. Already seeing temperatures near or at 100 degrees in the southwest. Based on current temperatures, we did bump up temperatures a little, mainly south and west of the Missouri River. Latest forecast soundings indicate moderately unstable airmass over central ND this afternoon but strongly capped. In the west, shear is marginal but instability is weak. Better instability is located to the west and south, although an isolated strong to possibly severe storm could brush the far southwest/south central or move into the far west this evening. Will need to monitor. UPDATE Issued at 916 AM CDT Sat Jul 25 2026

Areas of fog continue mainly in the south central into the James River Valley. Visibilities have improved some and expect this trend to continue as we warm up this morning. Minor updates due to clouds and fog, otherwise no changes to the going forecast at this time.

UPDATE Issued at 638 AM CDT Sat Jul 25 2026

We are starting to see more widely scattered low visibilities from patchy fog, especially in parts of the northwest and north central, as well as the James River Valley area. Some of this fog is very shallow ground fog, which is what was recently observed at the office. The expectation is this should burn off through mid-morning but those out and about this morning could encounter sporadic reduced visibilities. A Special Weather Statement is out until the top of the hour but will likely issue another larger one to cover this hazard.

DISCUSSION

Issued at 332 AM CDT Sat Jul 25 2026

This morning, the synoptic pattern across the CONUS was characterized by a stout upper high over the Four Corners region, with the ridge axis extending over the Northern Rockies and into the southern Canadian Prairies. Surface high pressure was centered in southwest Manitoba, with generally light and variable winds that aid in the potential development of fog across the forecast area this morning. A few automated sites in the northwest are starting to report moderately reduced visibility, but webcams look pretty clear, at least for now.

Underneath the ridge, a potent low-level thermal ridge extends across the state, with 850mb temperatures as warm as 29 degrees C over southwest North Dakota. A Heat Advisory is in effect for much of western and central North Dakota this afternoon through Sunday, with the exception of our northern two tiers of counties. Ambient air temperatures will generally range from 95 to 105 today, with heat indices at a similar level.

HRRR smoke model output is similar to yesterday, although sky observations didn't seem to show quite as much smoke as we would have expected based on levels the model was advertising. However, still carrying mention of patchy smoke, with some potential for minor surface impacts. Otherwise, mainly sunny today, just could be hazy sunshine depending on how thick the smoke aloft ends up.

A transient shortwave and weak surface low are progged to track through northern South Dakota, with low PoPs skirting our southern counties. SPC isolated thunderstorms area (level 1 out of 5) tags our extreme far southwest, but thinking any potential for stronger to severe storms is pretty low, with deterministic guidance showing instability at 1000 J/kg or less.

Hot and dry weather continues on Sunday, with similar high temperatures as today and the Heat Advisory continuing. Main forecast concern on Sunday is near critical fire weather conditions, generally for areas south and west of the Missouri River. Minimum relative humidity will be in the mid to upper teens for this area, but breezy northwest winds around 20 mph are enough to likely reach near critical conditions.

Not many changes are expected looking ahead to the forecast for next work week. NBM temperature percentile spreads are relatively small, indicating high confidence in max temperatures staying in the 90s, if not around 100 degrees F. There are on and off chances for showers and thunderstorms as embedded waves move through and the ridge axis shifts around the region, but no one day stands out in particular. There is potential for storms to be strong to severe during this period per NSSL and CSU machine learning probabilities.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1215 PM CDT Sat Jul 25 2026

VFR conditions are forecast through the 18Z TAF period. Only some mid and high level clouds expected. Generally light winds today and tonight will increase from the south on Sunday over central ND, and increase and shift northwest over western ND. Will monitor for patchy fog, but currently too uncertain to mention at any TAF site.

BIS WATCHES/WARNINGS/ADVISORIES

Heat Advisory until 9 PM CDT /8 PM MDT/ Sunday for NDZ017>020- 022-023-025-031>033-035>037-040>044-046>048-050-051-057>062.