textproduct: Bismarck

KEY MESSAGES

- Isolated to scattered severe thunderstorms are possible each day today through Sunday.

- Near to slightly above average temperatures to continue today through early next week.

- Breezy to windy conditions combined with lower humidity values may bring increased fire weather concerns on Monday.

UPDATE

Issued at 941 AM CDT Fri Aug 28 2026

Elevated showers and thunderstorms continue to fester along a band of mid-level WAA sweeping from west to east across the state. So far, no hail has been reported, but MESH has continued to suggest penny to nickel size hail is possible in some of the stronger storms (now most located near the Canadian Border). MUCAPE around 500-1000 J/kg and effective shear around 35-45 knots should continue to support the potential for this elevated convective to potentially produce penny to nickel size hail. Wind gusts associated with this activity have been relatively tame so far with only gusts up to 25 to 30 mph at times. Additional showers and storms continue to redevelop behind the initial broken cluster of showers and storms, so some areas that have already seen rain this morning could get a second round. While some locally heavy rain has occurred with this activity, it remains brief in nature, and localized flooding is not a main concern at this time.

DISCUSSION

Issued at 414 AM CDT Fri Aug 28 2026

Thunderstorms are starting to develop along an elevated warm front, associated with and upper level wave, and low level jet. Currently the shear is low to modest, and most of these storms appear to be fairly stacked vertically as they tap into the abundant elevated CAPE. This elevated CAPE with these storms along with some steep mid level lapse rates, could still bring a stronger pulse like storm with some near severe hail and winds gusts are possible this morning. However, instability should be limited the more east they travel. Thus the window for severe storms this morning still appears to be limited yet will be worth monitoring. The rest of today, surface low begins to form just to the south, while the surface warm front lifts across the area. Meanwhile, increased dewpoints and slightly increased temperatures in the 80s to lower 90s are found. A breezy southerly wind could also be found, mainly in central and eastern portions. Another round of isolated severe thunderstorms are possible this evening into the overnight hours as another shortwave moves through in proximity to the surface low. SPC has maintained a Marginal Risk to much of the area as a result. There is a brief window late this afternoon and this evening of stronger shear aligning with decent CAPE. Strong capping at the surface would have to be overcome, thus storms may be more elevated today. If a stronger elevated storm can develop, or a surface based storm can break through the capping, then a discrete storm or two could bring large hail to golf ball sized and damaging winds near 60 mph. Thus increased the messaging for hail size slightly for today. Tornado threat still appears low, given high LCLs. However, with the surface low near by an isolated tornado is possible, especially in the higher moisture area in the southeast. The window for this would be limited today, and confidence is not high enough to include in the severe weather messaging for today. Broad surface low combined with lingering elevated instability will make at least slight chances for showers and thunderstorms through the night. Shear diminishes tonight, which should limit the severe weather threat. Of note is the pulling of increased moisture from the south, and the increased Pacific moisture aloft. Thus some localized heavy rain is possible tonight, with the better chances coming this weekend as this setup remains. Lows tonight will generally be near 60 degrees.

This weekend, isolated to scattered severe thunderstorms will remain possible each day as the surface low lingers across the area and combined with embedded shortwaves aloft. SPC has a broad Marginal Risk each day, with a Slight Risk in the south on Saturday. The mentioned open gulf scenario will bring increased dewpoints and pwats throughout the weekend, leading to some increased chances for heavy rain. Pockets of 1 to 2 inches of QPF are starting to show up on the HREF ensemble max precipitation stamps. These will be highly thunderstorm dependent. Otherwise large hail and damaging wind gusts will be the main sever weather threats through the weekend. More of a multicluster storm mode looks to play out Saturday, likely limiting the hail threat to around the size of ping pong balls and wind gusts to 60 mph. Sunday will be worth monitoring as a more robust upper level wave and cold front look to move through, which could provide more of a discrete storm mode bringing slightly bigger hail and wind threat. The tornado threat looks low for Saturday, yet could be slightly increased on Sunday depending how the warm front and following cold front setup. Otherwise look for slightly above normal high temperatures in the 80s to continue into Saturday, cooling slightly on Sunday. With increased dewpoints and generally light winds the fire weather danger should remain low.

Monday, a fairly stacked low in southern Canada will skirt to our north bringing generally dry yet windy conditions. Perhaps some advisory level winds are possible with this system, along with some increased fire weather concerns. After this system a combination of weak ridging and southwest flow will keep temperatures near to slightly above normal. Embedded wave in the southwest flow could bring at least slight chances for showers and thunderstorms. Currently these look to return more mid to late week as another low develops off the Pacific Northwest. Fire weather concerns may continue through next week as continued warm temperatures lower afternoon humidity values. This is dependent on any strong wind developing from the mentioned waves in southwest, which confidence at this time looks low. Thus something to monitor for next week.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 650 AM CDT Fri Aug 28 2026

Overall VFR conditions expected through the forecast period. There are two round of showers and thunderstorms possible through the forecast period. The first is ongoing as a broken line of thunderstorms moves from central to east. Added in TEMPO and PROB30 groups for most sites to account for this. The second being this evening which only had enough confidence for PROB30 groups in western and some central sites. Any thunderstorm could bring brief MVFR conditions. An isolated severe storm is also possible with either round of storms today and tonight, with large hail and damaging winds the main threats. Otherwise look for a steady southerly wind from 10 to 20 knots with a few higher gusts for most sites through today, diminishing to light and variable tonight.

BIS WATCHES/WARNINGS/ADVISORIES

None.