textproduct: Bismarck

KEY MESSAGES

- Showers will push across the state through tonight.

- Patchy to areas of fog may return later tonight into Thursday morning.

- Highs mostly in the 60s and 70s and lows around 40 to 55 through early next week. Breezy conditions expected today, Friday, and Saturday.

- Medium to high chances for rain in central and eastern North Dakota Friday afternoon through Friday night, then statewide early next week.

DISCUSSION

Issued at 228 PM CDT Wed Sep 23 2026

Upper level wave will continue to push eastward across the area this evening. This will lift the ongoing rain north and east. Behind this wave will be a trailing surface low that could bring a second round of showers and perhaps a few strong to severe thunderstorms. Modest CAPE at the surface and mix layer may briefly become uncapped later this afternoon through the early evening. Shear also looks to be modest, with the higher shear pushing east following the upper level wave. In addition, lingering low clouds could also limit heating this afternoon, and the total amounts of instability. Thus severe storms remain quite conditional through this evening. If a stronger storm can develop, nearly straight hodographs would indicate hail being the main threat. Given the limited instability, hail size would likely be around an inch in diameter today. Winds to 60 mph are also possible, although DCAPE looks to be low. The tornado threat is also low today, despite some increased SRH. If stronger surface heating can be found today, then perhaps a non-supercell tornado is possible yet still pretty low chance. For the most part showers and thunderstorms will push east and out of the CWA overnight tonight. Light winds and lingering low level moisture could then bring some fog tonight into Thursday morning. Look for lows in the upper 40s to mid 50s. The rest of Thursday then sees clearing skies under a ridge of high pressure. This will also provide for light winds and some warming temperatures, with highs in the 70s. Dry conditions look to continue Thursday night, with similar lows in the upper 40s to mid 50s. A switch to southerly flow overnight could again provide some increased moisture, and perhaps some patchy to areas of fog. A developing surface low to the west will bring a breezy southerly flow on Friday, and maintaining temperatures near normal. As the upper level ridge moves eastward southwest flow looks to take over aloft, which could bring some chances for showers, mainly south, central, and east. Limited instability should limit the thunderstorm threat.

This weekend, southwest flow aloft looks to remain across the area, although the broader trough causing this looks to lift more into western Canada. Thus temperatures look to be near 70 degrees each day, with lows in the mid 40s to mid 50s. Chances for precipitation looks to be limited through the majority of the weekend. Saturday could see a weak cold front move through. This may provide some low chances for showers and thunderstorms in the north and east. This front could also turn a breezy southerly wind into a breezy westerly wind. Zonal flow aloft becoming southwesterly could bring mainly dry conditions during the day Sunday, although increasing moisture will bring increased cloud cover through the day.

The main feature of interest heading into early next week remains a deep but progressive trough moving from the Pacific Coast late Sunday into the Plains by mid week. Ensembles remain similar to the previous shift, and are in good agreement on the existence of the trough, but uncertainty in timing and placement of its strongest energy is evident. Cluster analysis reveals two distinct and nearly- equal outcomes in the evolution of the trough: one keeps the base of the trough over the Desert Southwest for a longer period of time, allowing a northern stream wave to deepen; the other is more progressive and keeps the base of the trough more north with some split flow like features. Then there are subsets within each of those outcomes that include a southern cutoff low in the former (very low probability) and split flow in the latter (nearly equal probability as no split flow). Regardless of these differences, all ensemble clusters show the highest probabilities for rain in southeast North Dakota early next week, and the lowest to the northwest. NBM PoPs begin to increase Sunday evening and are highest during the day Monday when some guidance, including CSU machine learning, indicates a conditional risk for strong to severe thunderstorms in a low CAPE/high shear environment. The arrival and passage of the deeper trough should trend temperatures cooler early next week, but still remaining near average as average values themselves (highs in the 60s and lows around 40 by the end of the month) are beginning to cool more steadily.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 710 PM CDT Wed Sep 23 2026

Low clouds will linger across the region tonight resulting in MVFR to IFR conditions. Clouds will likely clear out tomorrow afternoon. Models are forecast patchy fog developing around the KXWA and KMOT area tonight while the southern terminals will likely see rain as another system move through the region. Winds will veer to the west as a surface low moves through the region, but winds will remain light before veering back to the southeast by tomorrow afternoon.

BIS WATCHES/WARNINGS/ADVISORIES

None.