textproduct: Bismarck

KEY MESSAGES

- Low clouds with patchy fog and mist are expected in parts of south central ND and the James River valley tonight.

- Low to medium chance for rain showers across south central ND into the James River Valley on Wednesday.

- Near to slightly above average temperatures Wednesday through the end of the week.

UPDATE

Issued at 950 PM CDT Tue Oct 27 2026

No significant changes were made with this update cycle. As of 0245z, GOES-East nighttime microphysics RGB imagery shows that stratus is redeveloping/expanding back west in south central ND in the previously-discussed favorable environment for low-level saturation beneath the stout inversion sampled in the 900 to 800 mb layer on the 00z Bismarck RAOB. Fog development is still possible too. Otherwise, incoming 00z model simulations suggest the Wednesday morning forcing and related low to medium rain shower chances may be trending a bit further southeast compared to earlier cycles.

UPDATE Issued at 705 PM CDT Tue Oct 27 2026

The shortwave trough moving from northwest ND into southeast SK the last few hours has taken on an impressive cyclonic curvature on both satellite and radar imagery. The last of the associated wrap-around light snow is lifting into southern Canada early this evening, leaving a dry forecast in tact the remainder of the evening. A surface pressure trough/effective warm front has advanced east-northeast to roughly the Missouri River, and is near a line from Williston to Bismarck and Mobridge as of 23z. This feature is expected to slow its east-northeast movement at the surface with the decrease in diurnally-driven mixing to its west, though shortwave-preceding warm air advection will result in continued warming aloft across the whole area tonight. An intense, 100 kt jet streak aloft is advancing east-northeast across the state as well, marked by notable drying in low- and midlevel water vapor imagery. Ascent in the left-exit region of that jet streak was earlier responsible in part for the strength of the upper-level shortwave and production of snow in northwest and north central ND, but the area will be in a region with more negligible forcing directly beneath the uncurved jet streak for the next 12 hours or so, until its right-entrance region moves into the region Wednesday morning. In the interim, the drying and warming aloft is providing a favorable setting for both the maintenance and strengthening of an inversion aloft, which in turn will favor low clouds (stratus) where low-level winds are more southerly and therefore resulting in weak moisture advection, e.g., south central ND into the James River Valley. We expect the recently-advancing back edge of stratus (which passed by Bismarck/Mandan just after 23z) to slow its advance the rest of the evening, and potentially retreat overnight. There's a medium chance of fog development in south central ND into the James River valley too, but forecast soundings suggest increasing winds just above the ground may temper an otherwise favorable thermal and moisture setting for fog. We therefore are maintaining only patchy fog in the overnight forecast at this time.

DISCUSSION

Issued at 257 PM CDT Tue Oct 27 2026

Decent trough from a lifting upper level low combined with temperature advection aloft and steep mid level lapse rates has created snow showers across the northwest this afternoon. At times these have produced moderate snowfall. This wave will continue to lift across the northwest and north central through this evening gradually moving this showers northward. Perhaps some light snow accumulations are possible, although main impacts will be brief visibility reductions below a mile at times. Meanwhile, lingering low level moisture ahead of this wave will continue low clouds along with patchy fog, mist, and perhaps some drizzle into this evening. Dry air intrusion should bring some clearing to the southwest alter this afternoon into this evening. Other than the southwest, most areas will see cooler temperatures continue through today. Tonight, some snow showers may linger near the Canadian border through the late evening hours. Otherwise a mix of clearing to cloudy skies will be found tonight. Cloudy skies look to be wedged in between lingering clouds in the north and increasing low level moisture in the south from a developing southerly flow. This southern push of moisture could return patchy fog and mist tonight into Wednesday morning. Lows tonight will greatly depend on this clearing, and generally be in the 30s. Stacked upper low then stalls in southern Canada on Wednesday. Weak warm front followed by a weak cold front will move across the area as a result. This could bring some rain showers to south central and southeastern portions, with a slight chance of snow mixed in. Southerly flow ahead of the mentioned cold front could also bring warming temperatures in the mid 40s to mid 50s, and some lower 60s, provided low clouds don't linger through the day. Cooler lows in the 20s are then forecast for Wednesday night behind this mentioned front. Light winds and weak ridging could also return some patchy fog Wednesday night into Thursday morning.

Ridging aloft then brings mainly dry conditions for Thursday and Friday, with temperatures near to perhaps slightly above normal. Winds will overall be light, although a breezy southerly wind may develop across the west on Friday. Clusters maintain a general ridge pattern for the upcoming weekend. As a result light winds and mild temperatures are forecast. Some cluster solutions try to kick out a weak wave into the plains this weekend, although most now keep this to our south. NBM is starting to trend lower with PoPs for this weekend, although does keep in some slight chances for rain showers. Clusters still showing increased rain chances early next week, yet the main upper low associate with this next disturbance starting to trend towards a more southern track. Depending on track of this system some breezy winds may also return early next week. Something to monitor going forward.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 950 PM CDT Tue Oct 27 2026

MVFR to IFR stratus is expected overnight in parts of central ND and the James River valley, including at KBIS (at least for a few hours) and KJMS. Patchy fog may also develop both underneath and near the edge of the stratus but wind speeds just above the ground may be sufficient to temper its formation. VFR conditions will prevail in western ND tonight, albeit with a low chance of fog in some locations. An area of rain showers is forecast to move across south central ND and the James River Valley Wednesday morning, but behind that system, we expect conditions to improve to VFR by Wednesday afternoon.

BIS WATCHES/WARNINGS/ADVISORIES

None.