FXUS63 KBIS 181748 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 1248 PM CDT Thu Jun 18 2026 .KEY MESSAGES... - Showers and thunderstorms returning this afternoon and evening. The threat for severe weather is low. - Temperatures below normal today, with highs mostly in the mid 60s to lower 70s and lows in the 40s. Slightly warmer and generally dry for Friday. - Near to slightly below seasonable temperatures, with daily chances for showers and thunderstorms, this weekend. && .UPDATE... Issued at 1242 PM CDT Thu Jun 18 2026 Northwest flow aloft with some weak embedded waves contributing to expanding diurnally driven CU fields across the Northern Plains, along with some light radar returns showing up across the region. Main push of showers and thunderstorms will develop into the region later this afternoon and evening as a stronger S/WV approaches and moves through the region. Main change with this forecast update was to add low POPs early on given latest observations. UPDATE Issued at 937 AM CDT Thu Jun 18 2026 The forecast for today remains on track. Updated hourly weather grids based on latest sat imagery and trends, with the main changes being to sky cover and to some extent POPs. UPDATE Issued at 652 AM CDT Thu Jun 18 2026 Limited updates needed this morning. Some patchy fog is showing up on satellite and webcams from about Baker, MT to the Bowman, ND area. Added in patchy fog through the mid morning hours in these areas. A very isolated shower has also formed in central ND, and may linger through the mid morning hours as well. Made some minor updates for this shower activity. Overall the forecast remains on track. && .DISCUSSION... Issued at 345 AM CDT Thu Jun 18 2026 Northwest flow aloft will be found today, with a weak upper level wave moving through later this afternoon through tonight. Lingering moisture in this flow will bring pockets of clouds this morning through this afternoon with a steady northwest wind also expected. As mentioned a weak upper level wave moves through this afternoon and evening, which is expected to bring showers and thunderstorms from west to east during this time period, and possibly linger into tonight. SPC has general thunderstorm risk for today. There is some modest shear yet weak instability this afternoon and evening. Perhaps an isolated stronger storm is possible as a result, although skinny CAPE profiles should limit the hail threat, and the lack of DCAPE should limit the wind threat today. Temperatures today will be slightly warmer and generally near 70 degrees. Showers and thunderstorms will push eastward tonight, with cool overnight lows in the 40s expected. Varying levels of cloud cover can also be expected for tonight. If some areas can clear up then perhaps some patchy fog is possible, although not currently in the forecast. Northwest flow aloft looks to continue for the Juneteenth Holiday, Friday, while a surface high builds in the west. The result will be generally dry conditions for much of the CWA, except some eastern portions that could remain impacted by a large upper low aloft in southern Canada. This low may also bring enough of a pressure gradient for some breezy northwest winds across the area for Friday as well. High temperatures will be similar today and generally near 70 degrees. This weekend, brief ridging moves through Saturday bringing mainly dry conditions to start. Some afternoon and evening showers and thunderstorms may be found in the west on Saturday as southwest flow aloft returns behind the mentioned ridge. Behind this ridge will also see a shift to east to southeast flow, which may become breezy in the west on Saturday. A more unsettled pattern is then expected for Sunday with a broad trough pattern, and nearby surface lows. Increasing moisture from a southerly flow is also expected, especially across the west. This could lead to morning showers and thunderstorms across the west, and perhaps some patchy fog. Upper level wave then moves across the region through the remainder of Sunday, while a secondary low moves to our south. This is forecast to bring increased chances for showers and thunderstorms, with a continued breezy east to southeasterly flow. Temperatures may also cool slightly for Sunday. The better instability looks to remain to our south this weekend, limiting the severe weather threat. This broad upper level trough could continue to linger across the region Monday, bringing similar conditions with slightly below normal temperatures and lingering chances for showers and thunderstorms. Tuesday through Wednesday next week still have moderate to high confidence in warming temperatures as a ridge is forecast to build to the west. Placement of this ridge will impact precipitation chances, with current guidance still providing slight to chance PoPs given some embedded waves in northwest flow aloft that may linger. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1242 PM CDT Thu Jun 18 2026 Mainly VFR conditions are expected through the 18Z forecast period. Increasing cloud coverage this afternoon as diurnal CU develops and expands, with some low VFR cloud ceilings at times. Another round of showers and thunderstorms are forecast as well this afternoon through this evening. Will keep PROB30 groups to account for the precipitation potential. Some brief MVFR conditions remain possible with these showers or thunderstorms. Look for steady westerly wind through the 18Z TAF period. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...NH DISCUSSION...Anglin AVIATION...NH