textproduct: Bismarck

KEY MESSAGES

- Isolated severe storms are possible later this evening into tonight. Best chances remain south of I-94. Main hazards will be up to ping pong ball size hail and up to 60 mph wind gusts.

- Isolated to scattered severe storms are possible Sunday into Sunday night. Large hail and damaging winds are possible along with locally heavy rainfall. A tornado cannot be ruled out on Sunday as well.

- Dry and windy conditions are forecast for Monday. Locations south and west of the Missouri River may experience near critical to critical fire weather conditions through much of Monday.

DISCUSSION

Issued at 154 PM CDT Sat Aug 29 2026

Early this afternoon, a broad and strong mid/upper ridge was centered over the southern and central plains with a vigorous deep layer trough progressing eastward out of the PNW. Out ahead of this trough, several perturbations were noted within southwesterly upper flow over the northern CONUS. Despite the copious amounts of upper level cloud cover across the region, modest destabilization is occurring this afternoon across North Dakota out ahead of shallow shortwave trough located over the central Rockies. As forcing for ascent arrives later this evening into tonight, isolated to scattered showers and storms are expected to develop across western North Dakota and gradually work their way eastward. Continued development and/or persistence of this activity may also be supported by subtle mid-level WAA overnight into early Sunday morning. The greatest coverage of showers and storms will likely be along and south of I-94, especially given that better forcing for ascent appears to be trending further south for tonight into early tomorrow morning. Activity this evening into tonight will struggle to contend with widespread convective inhibition, and chances for a couple of isolated severe storms before 06Z appears to be waning given the latest short term guidance. However, elevated instability along the axis of mid-level WAA overnight into early Sunday morning will be fairly decent (generally around 1500-2000 J/kg of MUCAPE). Effective shear around 30 knots could support some organized elevated convection capable of hail up to ping pong ball size. Damaging wind gusts appears less likely, but an isolated instance of a 50-60 mph wind gust cannot be ruled out overnight and early Sunday morning.

Sunday appears to be quite the complicated setup for potential severe weather across North Dakota. A strong and deep upper trough will lumber eastward across southern Alberta during the day on Sunday with a sharp lobe of vorticity expected to round the southern end of the trough and kick out across eastern Montana and North Dakota. This should provide significant forcing for ascent across the northern CONUS for widespread showers and thunderstorms Sunday afternoon through Sunday night. Guidance has generally backed off the idea that shower and thunderstorm activity will be ongoing through much of the morning hours on Sunday. This seems a little off given the amplitude of upper level diffluence that will be overspreading the region as early as Sunday morning, but it's likely other factors are at play such as subsidence behind any activity the occurs late tonight into early Sunday morning. With short-range models backing off on morning convection across the state, this leaves the door open for potent destabilization across the forecast area. Model soundings across the warm sector Sunday afternoon show an uncapped airmass with ample instability around 2000-2500 J/kg. Shear will also be conducive for some organized convection with 0-6 km shear around 25 to 35 knots. Given the amount of synoptic ascent, the sharpness of the surface frontal boundary, and shear vectors parallel to said boundary, the expectation is for thunderstorms to rapidly grow upscale. With a linear storm mode favored, the main concern will be damaging wind gusts around 60-70 mph. At this time, it appears the hail threat will be limited to the first couple of hours after convective initiation when storms still have the opportunity to be semi-discrete. Lastly, a tornado or two cannot be ruled out where surface winds will be slightly back along a weak warm front draped across the state. The primary difference in the guidance at this point is the location of the warm sector. Solutions, like the HRRR and ARW, show a psuedo-dryline developing in the vicinity of the US-83 keeping warm, humid air east of this corridor. Meanwhile, other solutions, like the NAM and NSSL, show this moisture gradient along the ND/MT state line. This may have an impact on the intensity of convection early, perhaps modestly suppressing thunderstorm activity in the drier solution. However, the overall severe threats remain the same regardless of which scenario plays out.

Monday also appears to be a somewhat busy day for much of North Dakota, though more for wind and fire weather concerns. 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% south and west of the Missouri River. This along with the aforementioned breezy conditions will support near critical to critical fire weather concerns across southwest 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.

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 /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1227 PM CDT Sat Aug 29 2026

A light and variable surface flow to begin the 18Z TAF period will become easterly across western and central ND this afternoon. VFR mid and high level clouds are expected today into early this evening and a scattered sprinkle or brief shower can not be completely ruled out, but most will remain dry. Isolated to scattered showers and a few thunderstorms are possible tonight and included a PROB30 at all sites. Confidence in where and when any convection would occur is currently too low for anything more than a PROB30. Late tonight into Sunday morning low stratus and fog is possible but again, too uncertain to include any widespread reductions to VSBY at this time.

BIS WATCHES/WARNINGS/ADVISORIES

None.