textproduct: Bismarck

KEY MESSAGES

- Cloudy, mild, and humid with patchy fog tonight into Saturday morning.

- Medium to high chances for light rain south and west of the Missouri River through much of the weekend.

- Seasonable temperatures through early next week, with highs mostly in the 60s and 70s.

UPDATE

Issued at 1202 AM CDT Sat Sep 19 2026

The only change to this update was to add a period of drizzle along the I-94 corridor from Bismarck to Dickinson. Webcams along the Interstate and as north to Beulah are showing drizzle. Guidance shows a period of low level omega right around 06Z but not much thereafter, so limited this to a 3 hour period for now from 06-09Z.

UPDATE Issued at 1010 PM CDT Fri Sep 18 2026

No major changes are needed for this update. Current conditions and trends have been blended into the forecast. A mention of patchy drizzle along and south of I-94 and east of the Missouri River has been extended until 1 AM, at which point guidance shows a loss of upward motion in the near-surface saturated layer. A few isolated showers also remain possible along and north of Highway 2 through the night.

UPDATE Issued at 653 PM CDT Fri Sep 18 2026

Overall, the forecast remains on track. Some minor adjustments were made to PoPs, sky cover, and fog, all based on observed and recent model trends. High confidence in persistent clouds also prompted some minor changes to forecast lows tonight (slightly warmer) and forecast highs on Saturday (slightly cooler).

DISCUSSION

Issued at 219 PM CDT Fri Sep 18 2026

Surface low currently over the Central Plains will ever so slowly churn eastward through this weekend. Simultaneously, blocking high over Ontario will slide eastward through tonight, though reinforcing blocking high will propagate towards Ontario from central Canada this weekend. While elevated dewpoints (for this time of year) and abundant low-level stratus will be common, including some drizzle in the far south central this afternoon, back to back highs will allow dry air to win out across most of the state through this weekend. There are a few exceptions, however.

First, shortwave energy today into tonight may allow additional shower and possibly thunderstorm development mainly in northwestern North Dakota, but also potentially the far north central along the International Border, and the far west central along the ND/MT border. Instability is generally expected to remain less than a 1000 J/kg with up to 30 kts of deep layer shear, so severe weather isn't expected. That said, small hail remains possible. Second, along the gradient between the aforementioned highs and low, which includes mainly areas south and west of the Missouri River, more organized rain/showers are possible Saturday through Sunday. These showers could expand into the northwest and further east as well, though confidence decreases rapidly the further east one goes. Once precipitation ends Sunday night, mostly dry conditions are expected through Tuesday before low chances return Wednesday afternoon through Wednesday night.

Seasonable high temperatures, albeit below average, are expected through this weekend with highs mostly in the 60s. Lows, on the other hand, will mostly remain on the higher side of average. For next week, a slight warming trend is favored with highs returning into the 70s for most locations, most days, by Wednesday.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 1202 AM CDT Sat Sep 19 2026

Ceilings are forecast to gradually fall through the overnight hours, with IFR to LIFR likely at all terminals by early Saturday morning. Fog/mist underneath the low clouds could also reduce visibility at times. Ceilings are forecast to gradually lift late Saturday morning through the afternoon, with MVFR still prevailing across southern North Dakota. A few light rain showers are possible over much of the western half of the state during the day Saturday. The highest probabilities for rain are in southwest North Dakota. Any rain is unlikely to cause categorical restrictions lower than those from clouds, and will keep the mention of a PROB30 only at KDIK, as per the previous shift. Winds will primarily be light and variable overnight, then east to northeast around 10-15 kts on Saturday.

BIS WATCHES/WARNINGS/ADVISORIES

None.