textproduct: Bismarck

KEY MESSAGES

- Patchy fog is possible across much of western and central North Dakota this morning.

- Isolated to scattered severe storms are possible today through this evening. Large hail and damaging winds are possible along with locally heavy rainfall. A tornado cannot be ruled out as well.

- Dry and windy conditions are forecast for Monday. Portions of western North Dakota may experience near critical to critical fire weather conditions through much of Monday. Areas along and north of Highway 2 could see winds gusts up to 50 mph.

- After Monday, near to slightly above normal temperatures along with near daily chances for showers and thunderstorms can be expected.

DISCUSSION

Issued at 417 AM CDT Sun Aug 30 2026

An initial upper level wave with a plume of monsoonal moisture will continue to lift across the area this morning bringing a broad area of showers and thunderstorms. Just enough instability and shear will provide for a few stronger thunderstorms, although the more severe weather looks to be confined closer to the low level jet in South Dakota. A lack of steep mid level lapse rates should also diminish the hail threat, while DCAPE values look somewhat on the low side for a wind threat this morning. Even so, there is some diminishing of the cap in the mix layer and storms that can develop in this area of diminished cap may access enough shear to produce a very isolated severe storm this morning. Of concern are localized heavy rainfall this morning as pwat values of an inch to 1.5 inches are observed. Storm motion is also a bit on the slow side this morning, giving storms some longer residence time. WPC currently has an excessive rainfall discussion for much of western and central ND to account for localized 1 to 3 inch rain amounts this morning. In fact, Hettinger reported over 2 inches when a heavier slow moving thunderstorm moved through overnight. These heavy rains could lead to some localized flooding and will have to be monitored through the morning. Lastly, areas without rain and any clearing could see patchy fog this morning as dewpoint values remain high and winds remain light. The rest of today, upper wave gets diffused as it moves east perhaps bringing a brief break to precipitation later this morning. Muggy conditions will remain with dewpoints in the 60s to lower 70s and highs in the mid 70s to mid 80s. SPC has maintained a Marginal Risk for severe weather this afternoon through this evening. Setup remains similar with a weak warm front left across the state after this mornings convection. A stacked lower pressure system moving across southern Canada will bring a cold front from west to east later today through this evening, while a surface low moves just to our south across SD. The result could bring a period of isolated to perhaps scattered severe thunderstorms. Shear values may only be modest today, yet CAPE remains around 2000 J/KG. Favorable jet location and higher dewpoints may also help sustain strong storms today. There is a brief window the shear vectors favor discrete cells this afternoon. This could lead to hail to golf ball size, and winds to 60 MPH. This window is also where the conditional tornado threat sets either along the mentioned warm front or near a triple point near the surface low. LCLs could be lower today too given the higher dewpoints. However, shear vector switches parallel quickly along the front, changing storm mode to linear quickly as well. STP values also are not forecast as high as recent days, yet could still approach 1. Overall a low tornado threat remains, and will keep messaging this conditional risk. Once storms go linear a wind threat from higher DCAPE and 0 to 3 KM shear values will be found. Winds up to 70 mph with perhaps some large hail with embedded supercells will be the main threats this evening. Pwat values of over an inch will linger through this evening as well. This could lead to some localized heavy rain again, although storm motion might be a touch increased by this evening given the cold front push. Even so HREF max ensemble QPF forecasts still showing 1 to 3 inches of rain still possible with these storms later today. Areas with heavy rain this morning followed by heavy rain later today will be the areas to monitor for localized flooding today. The eventual line of severe thunderstorms should push eastward by late this evening. Dry air behind this front looks to clear skies quickly tonight. A steady west wind should limit the fog potential tonight, although areas with higher rainfall amounts could see patchy fog. Cooler lows tonight in the mid 40s to mid 50s can also be expected.

Monday, post frontal conditions could bring strong winds and fire weather concerns for much of North Dakota. The surface low and upper low are forecast to become more vertically stacked over Saskatchewan, and a tight pressure gradient is expected across southern Saskatchewan/Manitoba into much of North Dakota. Mostly clear skies should allow for deep mixing across these areas, and uniform flow in the boundary layer should allow for efficient mixing of stout winds to the surface. Model guidance suggests 850 mb winds could be in the neighborhood of 45 to 50 knots, mainly across northern North Dakota. Should these winds mix down to the surface, it's possible some locations along and north of US-2 could experience 45 to 55 mph wind gusts during the day on Monday. It's possible a wind advisory may be needed for these areas late Monday morning into Monday afternoon. Further south, the expectation is for wind gusts to be in the 30 to 45 mph range. RH values will generally be around 20-30% to areas along, south, and west of the Missouri River. This along with the aforementioned breezy conditions will support near critical to critical fire weather concerns across a wide portion of North Dakota. Today's forecast has shifted these fire concerns slightly northward, thus adjusted messaging to include much of western North Dakota. As the surface low gradually weakens and lifts northeast, the pressure gradient will begin to relax by late afternoon. Thus, breezy conditions should generally come to an end by sunset Monday evening. This westerly wind could also bring some wildfire smoke back into the area. Confidence is not high enough to place in the forecast at this time.

Periodic chances for showers and storms remains in the forecast from Tuesday through the end of next week. Mid to long range guidance continues to be on board with a series of systems traversing the northern plains around mid/upper ridging remaining over the central and southern plains. The best chances for showers and storms next week will likely be Wednesday night into Thursday morning as a stout upper trough is forecast to eject into the northern plains. Exact details remain a bit murky this far out, so stay tuned for updates to the forecast for this time period over the next few days.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1257 AM CDT Sun Aug 30 2026

MVFR to VFR conditions could be found tonight as an initial round of showers and thunderstorms lifts across the forest area. Most sites have a TEMPO or PROB30 group for thunderstorms to account for this. Any clearing ahead or behind these storms could lead to some IFR to MVFR ceilings and perhaps visibilities with patchy fog. Confidence in this occurring is low, although KMOT and KJMS are already seeing some lower clouds trying to form. After the initial round of showers and thunderstorms moves through Sunday morning, MVFR to VFR ceilings will prevail across much of the area through the day. Later in the day through the evening another round of thunderstorms looks to push from west to east, bringing MVFR and isolated severe conditions. Prevailing and PROB30 groups for these storm chances were used at most sites. A south southeast wind will be found for Sunday, changing to a westerly wind later Sunday through Sunday night as a cold front moves through.

BIS WATCHES/WARNINGS/ADVISORIES

None.