textproduct: Bismarck

KEY MESSAGES

- Medium to high chances for showers today into tonight, with isolated to scattered thunderstorms during the afternoon and evening. A few storms may become strong to severe west and south of the Missouri River.

- 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.

UPDATE

Issued at 1002 AM CDT Wed Sep 23 2026

Limited updates needed this morning, although made some very minor adjustments to PoPs based on the latest radar trends. Of note is SPC has introduced a Marginal Risk for severe weather in the southwest later this afternoon through this evening. This risk is conditional on the atmosphere destabilizing this afternoon. If this can occur marginal instability and shear could create isolated strong to severe storms as a surface feature moves through. Main hazards would be hail to the size of a quarter and wind gusts to 60 MPH.

UPDATE Issued at 658 AM CDT Wed Sep 23 2026

Showers are beginning to move into far southwest North Dakota as of 645 AM CDT. Expect this trend to continue through mid morning, with an occasional thunderstorm possible. Patchy fog/mist has also developed across parts of western and south central North Dakota early this morning. Aside from Bowman County, visibility has remained at or above 2 miles.

DISCUSSION

Issued at 416 AM CDT Wed Sep 23 2026

A shortwave trough will eject off the Northern Rockies this morning, reaching the western Dakotas by the end of the day. Ahead of the shortwave, strong southerly return flow between a lee trough over central Montana and broad high pressure stretching from the Great Lakes to New England and the Canadian maritime provinces has maintained breezy conditions, widespread stratus clouds, and mild temperatures in the 50s over western and central North Dakota early this morning. The approaching shortwave, which is projected to be collocated with the left exit region of an upper level jet streak, is forecast to bring areas of showers across the state during the day today, with the highest chances in the southwest this morning and northwest and central during the afternoon. There could also be some lighter showers from the James River Valley to the Turtle Mountains this morning on account of warm air advection induced by the low level jet. Low stratus is forecast to keep the boundary layer stable over central North Dakota this afternoon, but an EML above the boundary layer could yield enough buoyancy for some embedded thunderstorms to develop. These storms are unlikely to be strong, but there is a scenario back to the west that will need to be monitored later today. Some CAMs, most notably the HRRR with high run-to-run consistency, initiate storms along the lee trough in west central and southwest North Dakota late this afternoon. This timing and placement is now projected to be concurrent with the arrival of the mid/upper level trough axis, which lends increased confidence in both development and maintenance of widely scattered thunderstorms. Clusters of UH tracks indicative of strong to severe convection have been common in HRRR guidance, with CAPE around 1000 J/kg and deep layer shear around 30 kts. One of the key factors likely to regulate whether strong to severe storms are able to develop is the erosion of cloud cover, which will be necessary to allow diurnal heating to sufficiently erode CIN. Because of this uncertainty and environmental parameters being barely supportive of severe convection, we will message a potential for strong thunderstorms during the late afternoon and evening, west and south of the Missouri River. Intensity of any evening storms should diminish by midnight, but showers and weaker thunderstorms may continue to propagate east/northeastward through central North Dakota late tonight. Aside from shower and thunderstorm chances, forecast highlights for today include a mostly cloudy sky and breezy south-southeast winds around 15-25 mph. Both wind and cloud cover could decrease in southwest North Dakota this afternoon, where high temperatures could reach the lower 70s. Elsewhere, highs are likely to be limited to the lower and mid 60s.

An upper level ridge is forecast to develop over the region on Thursday, with the strong surface isobaric gradient shifting eastward. Decreasing clouds through the day should allow high temperatures to reach the lower 70s east to around 80 far west. On Friday, the upper ridge is forecast to shift eastward as a potent trough lands on the Pacific Northwest, all while a shortwave lifts off the Central Rockies toward the Northern Plains. Latest model guidance has slowed the shortwave, but NBM PoPs have significantly increased to around 60 to 80 percent in the eastern half of the state, temporally increasing from Friday afternoon through Friday night before diminishing Saturday morning. Preceding cloud cover and southeasterly surface flow will likely bring high temperatures back into the 60s in south central North Dakota on Friday, but there is still a chance for lower to mid 70s across the west and north. As the late Friday shortwave departs, the Pacific Northwest trough is forecast to open and spin an occluding cyclone into Alberta and Saskatchewan on Saturday. The southward extending cold/occluded front is forecast to move across the state Saturday afternoon and evening, with some timing uncertainty. This keeps the high temperature forecast less certain on Saturday, but the NBM has been consistently advertising lower to mid 70s in its 50th percentile output.

The main feature of interest heading into early next week is a deep but progressive trough moving from the Pacific Coast late Sunday into the Plains by mid week. Ensembles 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 north of the Deep South. 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 /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 658 AM CDT Wed Sep 23 2026

Nearly all of western and central North Dakota begin the 12Z forecast cycle with at least MVFR ceilings. IFR to LIFR ceilings were spread over southwest and into far south central North Dakota, and these could expand north and eastward through the morning. Ceilings are likely to gradually lift to VFR in western North Dakota through the afternoon. In central North Dakota MVFR ceilings are expected to prevail through the afternoon and lower back to IFR or LIFR this evening through tonight. Fog could also develop across all of western and central North Dakota later tonight.

Areas of showers are forecast to move across the state from southwest to northeast throughout the day today and into tonight. Some thunderstorms will be possible during the afternoon and evening, a few of which may become strong with small hail and erratic gusty winds. Heavy rain may cause brief periods of MVFR to IFR visibility restrictions. Confidence in timing and location of showers and storms is not high enough to include any mentions beyond PROB30 groups at this time.

Winds will remain southeasterly around 10-15 kts this morning, with some higher gusts at times. The southeast winds should then increase closer to 15-20 kts across central and eastern North Dakota this afternoon, gradually diminishing this evening through tonight. In western North Dakota, winds are forecast to gradually become light and variable this afternoon and evening.

BIS WATCHES/WARNINGS/ADVISORIES

None.