textproduct: Bismarck

KEY MESSAGES

- Very low humidity values combined with winds becoming northerly and gusty will result in near critical fire weather conditions in western and especially southwestern North Dakota through this evening.

- Isolated thunderstorms possible this evening over south central North Dakota into the James River Valley. A few storms could be severe with golf ball size hail and 60 mph wind gusts being the main threats.

- Low to medium chances (mainly 20 to 50 percent) for precipitation Sunday into the upcoming work week. Isolated strong to severe thunderstorms may return to southern North Dakota late Sunday afternoon through Sunday night.

- Abundant wildfire smoke aloft expected to continue through the weekend, with some patchy smoke at the surface during the day and evening hours.

UPDATE

Issued at 605 PM CDT Sat Aug 8 2026

Convection is trying to get going over far south central ND from just south of Bismarck into northern Sioux County. This is in an area of around 2000 J/Kg of ML Cape and 50-55kts of Effective shear. With the shear vectors crossing the surface trough near perpendicular, supercells are possible if updrafts can be sustained. The problem looks to be that the area of uncapped atmosphere is minimal as capping increases to the east. Also SPC Mesoanalysis pages shows increasing in the 01-02Z timeframe. limiting the window for surface based convection. If convection can get going early this evening there is enough instability aloft that some elevated convection could linger into the mid to late evening hours as the convection moves off to the east. The greatest probability for strong to severe convection looks to be through around 01-02Z. Golfball sized hail and 60 mph winds would still be the main threats. Will continue to monitor.

No changes other than adjusting pops some through this evening far south central and into the James River Valley. Updated text products will be transmitted shortly.

DISCUSSION

Issued at 250 PM CDT Sat Aug 8 2026

Inverted surface trough will push eastward across the southern half of the state tonight. Meanwhile a weak backdoor front will push across the north during the same time, possibly influencing the surface trough and associated warm front. To start, as the trough moves east, increased northerly winds will be found with some very low RH values in the teens across western portions. A couple hours of near critical fire weather conditions are possible as a result through this evening, especially in southwestern portions. This feature will meet abundant CAPE and shear in south central and southeastern portions this evening, with a shear vector favoring discrete supercells. There are brief periods the surface and mix layers are limitedly capped, although for the most part much of the instability is elevated. There is also a brief period where hodographs would support rotating supercells vs splitting cells with weak rotation. Thus there remains a conditional risk for isolated severe storms through this evening. Main hazards will be hail to golf ball size given the possibility for discrete cells combined with modest to high CAPE and shear, along with winds to 60 mph. LCLs look too high for a tornado threat despite some low STP numbers this evening. Thunderstorms will likely not be surface based which also limits the tornado threat this evening. The mentioned backdoor front should push the thunderstorm activity into SD tonight, although lingering instability will bring isolated thunderstorm chances through the night across the southeast. Lows tonight will be in the 50s. There are some improved RH recoveries tonight, although a steady northeast wind should limit fog formation. Abundant wildfire smoke aloft will also be found through tonight and again on Sunday. Patchy smoke may mix to the surface through this evening and again Sunday through Sunday evening.

Surface high lingers across the state Sunday morning, then gets nudge slightly northward. The stalled boundary to our south also gets nudge slightly northward and turns into a weak warm front. By late Sunday afternoon and especially through Sunday night modest CAPE and shear return along this boundary, with perhaps additional help by a mid level wave in northwest flow. This could bring another round of isolated to perhaps scattered showers and thunderstorms. SPC has returned and expanded a Marginal Risk to much of southern ND for Sunday through Sunday night. Hazards will be similar to tonights, with golf ball sized hail and winds to 60 mph. Storm mode may start out discrete then go to more of a linear mode as storms progress along the boundary Sunday night. Otherwise look for more seasonable temperatures Sunday and Sunday night with a steady east wind. Increased humidity values from slightly cooler temperatures should also improve the fire weather concerns for Sunday.

Zonal flow pattern will keep temperatures near normal to start next week. Disturbances within this westerly flow could also provide near daily chances for showers and thunderstorms. The unstable boundary found this weekend could linger as well perhaps bringing isolated strong to severe thunderstorms. SPC has clipped some south central portions with a Marginal Risk on Monday as a result. CSU-MLP also showing this signal for Monday and again on Tuesday. Of note is WPC having a Marginal Risk for excessive rainfall in southern and some western areas Monday through Wednesday, with the most widespread coverage on Tuesday. Pwats are slightly increased on these days and will also depend on the amount of thunderstorms that can develop in one area along this boundary. Clusters then indicate either a continued zonal flow pattern or perhaps a shift to a weak broad trough pattern could return mid to late week. This could result in further cooling of temperatures, with continued near daily chances for showers and thunderstorms.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 605 PM CDT Sat Aug 8 2026

VFR ceilings and visibility is found at all terminals to begin the 00Z TAF period. Showers and thunderstorms are expected to develop over portions of south central North Dakota this evening into early tonight, with some weak development already evident over the Missouri River at the time of this update. While the ingredients for strong to marginally severe storms will be available across the south central this evening, whether or not these ingredients will line up spatiotemporarily is still uncertain. Thus, have opted to use PROB30 groups for light TSRA at KBIS and KJMS through the mid evening with this update. Another round of showers and storms will be possible across far western North Dakota near the end of the TAF period. Otherwise, prevailing smoke aloft will continue to promote hazy skies over the forecast area through the TAF period. Winds at the start of the TAF period are turning cyclonically around a center of low pressure passing across southern North Dakota, becoming somewhat breezy with speeds around 12 to 15 knots and gusts up to 25 knots. As the low center passes off into South Dakota, winds are expected to diminish through the mid to late evening, becoming light out of the north to northeast overnight. Winds will then organize and turn anticyclonically around a center of high pressure diving in out of Canada Sunday morning through the end of the TAF period, becoming breezy around 12 to 15 knots and gusting up to 25 knots over portions of the southwest and south central.

BIS WATCHES/WARNINGS/ADVISORIES

None.