FXUS63 KBIS 250930 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 430 AM CDT Sat Oct 25 2025 .KEY MESSAGES... - Patchy to areas of fog this morning. - Above normal temperatures for late October today (Forecast highs in the 60s to around 70, with normal values in the lower 50s). - Precipitation chances return Sunday night and continue into Monday night/Tuesday. Greatest chances central into eastern North Dakota Monday (50 to 80 percent). - Near normal temperatures expected for the upcoming work week. && .DISCUSSION... Issued at 410 AM CDT Sat Oct 25 2025 Currently, high amplitude upper level ridge across the Northern Plains this morning, with a long wave trough developing across the western CONUS. Southerly flow across the Dakotas with surface high pressure over the Great Lakes region and a developing sfc trough in the lee of the Northern Rockies. Scattered upper level clouds rotating around the ridge axis aloft, with a mild boundary layer contributed to morning temperatures mainly above freezing early this morning. High res models continue to portray fog development across the James River Valley this morning, with this underway now as evident via satellite imagery. Area of low stratus also advecting northward across the South Dakota James Valley towards my southeast counties. Will be monitoring this area for potential fog headlines. Right now aerial coverage is limited and some uncertainty what the stratus will do to any fog. Gradient forcing increases across the Dakotas today as the lee side sfc low continues to develop in response to the above mentioned upper trough developing east today. The increase in return flow/mixing and the position of the upper ridge axis will all contribute to sustained WAA and another day of very mild temperatures today (mid/upper 60s-lower 70s forecast...with normal high temps in the lower 50s). The initial evolution of the overall weather pattern remains unchanged from previous model runs late this weekend. The upper trough continues to develop eastward Sunday, with a strong 150 knot jet streak poking into the Pacific Northwest. Initial closed upper low develops within the trough, lifting north/northeast into central Alberta/Saskatchewan Sunday/Sun night along with an associated sfc low. Another strong embedded impulse and strong dynamics on the nose of the upper jet will amplify the mid/upper level trough Sun night into Monday, with an associated sfc trough/frontal boundary developing from across eastern Colorado north/northeast across central South and North Dakota. This feature coupled with multiple embedded waves lifting north/northeast from the base of the trough across the Dakotas will be the focus for accumulating rainfall. Models/NBM have shifted back west with the sfc trough/frontal boundary placement, and thus have shifted west for POPs and QPF. Decent accumulations are also advertised by NBM (quarter to 3 quarters of an inch central and east), and agree given the overlap of Div Q forcing and low level forcing/frontogenesis. Rain chances gradually taper over the west overnight Monday, with chances gradually tapering elsewhere from west to east early Tuesday. Afterwards, a fairly progressive pattern is favored amongst ensembles for the remainder of the work week, with models showing the potential for a mid level shortwave/frontal passage mid to late next week. Temperatures are also favored to be closer to normal for next week. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 112 AM CDT Sat Oct 25 2025 VFR conditions with some high clouds moving across the region during the 06 TAF period. Patchy to areas of fog forecast later this morning, mainly across the James River Valley impacting KJMS (IFR-LIFR conditions will be possible). Breezy southerly winds expected during the day Saturday, with LLWS possible across central areas of North Dakota Saturday evening/night. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...NH AVIATION...NH