618 FXUS63 KBIS 290826 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 326 AM CDT Mon Jun 29 2026 .KEY MESSAGES... - Another round of isolated to scattered severe thunderstorms is possible today. Main hazards will be hail up to 2 inches in diameter and wind gusts up to 70 mph. An isolated tornado is possible as well. - A gradual warming trend is expected through Thursday or Friday with above average highs favored. A cooling trend back to near average highs is then favored for the holiday weekend. - Scattered showers and thunderstorms are possible during the holiday weekend. && .DISCUSSION... Issued at 326 AM CDT Mon Jun 29 2026 Another round of isolated to scattered severe thunderstorms is possible today. High pressure over the southeastern CONUS and low pressure over central Nebraska/South Dakota will continue pumping direct Gulf moisture into the eastern half of North Dakota today. This will result in a very buoyant atmosphere across much of the state, especially along and east of Highway 83. Combined with excessive shear with 50 to 65 kts of 0 to 6 km bulk shear, isolated to scattered severe thunderstorms are possible later this morning and especially afternoon. This is a conditional threat with a lot of uncertainty. For one, the exact path the aforementioned surface low takes as it lifts northeastward will impact where the highest severe threat is, especially in regard to the location of the triple point for potential tornadogenesis. Second, upper level low aloft is present over Montana and is expected to lift northeastward into Manitoba today through tonight. However, it's not exactly certain if the best upper level support will arrive in time before lifting surface low eventually cuts off aforementioned Gulf moisture. In addition, showers and thunderstorms both incoming from South Dakota and new development this morning could help modify the environment for this afternoon. For example, the part of the forecast area with the highest coinciding CAPE and shear values is the James River Valley. However, the RAP forecast sounding suggests the potential for rain in the James River Valley much of this morning. If that happens, it's not even certain that sky cover will clear thus potentially preventing environmental recovery. Regardless of how potential severe weather evolves, as previously mentioned, surface low will cut off Gulf moisture as it lifts northward. As such, the severe weather threat should end by late evening. In addition, that will also result in mostly dry conditions tonight through Tuesday night. Beyond Tuesday, periodic shower and thunderstorm chances are expected through the remainder of the week, including the holiday weekend. The highest probability for precipitation is currently Saturday evening. While this morning's CSU machine learning run hasn't come in, yesterday's suggestion of at least low severe thunderstorm chances this holiday weekend remains reasonable. However, deterministic models continue to suggest direct Gulf moisture is not favored to return this week, which could at least help limit the coverage and intensity to some degree. High temperatures are expected to gradually trend up through Thursday or Friday. However, the downward trend of these warmest temperatures continues. The warmest days per the latest NBM guidance is now Thursday and Friday with current forecast highs in the 80s to low 90s. This is only a bit above average considering highs for this time of year are generally near 80. The current NBM forecast is then for temperatures to drop down to around average for the holiday weekend itself. Granted, some uncertainty does remain with the extended temperature outlook. Other notes: First, patchy fog has developed over much of central North Dakota, though should lift by mid-morning. Localized dense fog isn't out of the question. Second, windy conditions are still expected on Tuesday and could approach advisory criteria. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1253 AM CDT Mon Jun 29 2026 Scattered showers and thunderstorms are expected through the night tonight. Shower and thunderstorm coverage is then expected to increase during the day Monday, especially for central and eastern North Dakota. A few severe thunderstorms are present over north central North Dakota as of this writing, though will likely become sub-severe over the next couple hours. Additional severe thunderstorms are possible during the day Monday, and should end from south to north in the evening. IFR ceilings/visibility and erratic winds are possible with any showers and thunderstorms that develop. In addition to shower and thunderstorm chances, patchy fog may develop along and east of Hwy 83 overnight, while MVFR/IFR ceilings should continue expanding across much of south central and eastern North Dakota overnight. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Telken AVIATION...Telken