FXUS63 KBIS 011843 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 1243 PM CST Sun Nov 1 2026 .KEY MESSAGES... - Patchy drizzle across much of North Dakota today. - Rain will fall across most of the state tonight through Monday night. There are medium to high chances for 1 to 2 inches of rain across much of southwest and south central North Dakota. - Near to above average temperatures and drier weather are favored mid to late next week. && .UPDATE... Issued at 1230 PM CST Sun Nov 1 2026 Visibility has greatly improved over the area, so the Dense Fog Advisory was allowed to expire. With that said, low clouds with patchy light mist/drizzle continues. UPDATE Issued at 926 AM CST Sun Nov 1 2026 Visibility in fog has been a bit slow to improve so far this morning, so have extended the Dense Fog Advisory until noon CST. Otherwise, remainder of forecast continues to be in good shape. UPDATE Issued at 631 AM CST Sun Nov 1 2026 Fog has lifted across much of south central North Dakota, but a few webcams continue to show dense fog along and just to the west of the James River Valley. The Dense Fog Advisory was extended until 9 AM CST for Eddy through Dickey Counties, matching the expiration time for western and north central North Dakota. The rest of the advisory in south central North Dakota was allowed to expire on time at 6 AM CST. It is not currently that foggy in Oliver, Mercer, McLean, and Sheridan Counties, but guidance does show potential for fog to redevelop there over the next couple hours. && .DISCUSSION... Issued at 417 AM CST Sun Nov 1 2026 A deep trough lies along the Pacific Coast early this morning, placing the Northern Plains under southwest flow. Surface and low level flow broadly remain southeast to southerly between high pressure over the eastern Great Lakes and low pressure near the Northern Rockies. Unseasonably high dewpoints within the persistent return flow continue to support dense fog across much of western and central North Dakota. South central North Dakota is an exception to this, at least temporarily. Consensus visibility guidance does lift the fog northward east of the Missouri River through early/mid morning, but also shows some redevelopment on a more widely scattered basis. Therefore, will allow the current Dense Fog Advisories to remain in place, with expiration times of 6 AM CST south central and James River Valley, and 9 AM CST elsewhere. Fog may be slower to lift in western North Dakota, but visibility should improve at most locations by early afternoon. An overcast sky will still prevail through the daytime hours, with a small chance of sunshine peeking through the clouds in the southwest. High temperatures today should be a few degrees warmer at most locations, with mostly mid 50s to lower 60s expected. The western trough will approach the Rockies tonight, inducing lee cyclogenesis in northeast Colorado. The surface low is forecast to quickly lift northeast into South Dakota/Nebraska on Monday, then stall and slowly drift eastward over the Missouri River Valley late Monday into Tuesday. Meanwhile, the parent 700 mb low is forecast to spin from western Wyoming tonight into South Dakota on Monday. All this sets the stage for a widespread rainfall event over much of North Dakota, but especially the southern half of the state, tonight through Monday night. Both HREF and REFS probability-matched mean QPF through Monday afternoon, which covers most but not all of the rainfall, places at least 0.5" for most areas south of Highway 2, at least 1" from around Beach to Harvey and southward (except a corridor from Dickinson to Bowman), and at least 2" over much of the southern James River Valley where strong frontogenesis underneath Q-vector convergence is forecast to produce mesoscale banding. Rain will quickly spread northeastward across the state this evening through tonight and gradually taper off from northwest to southeast Monday afternoon through Monday night. Some lighter rain could linger in far south central to southeast North Dakota on Tuesday, but most of the day will be dry. Temperatures will remain above freezing through the duration of precipitation, with little diurnal variation. Lows tonight are forecast in the lower 40s to lower 50s, with highs on Monday in the mid 40s to mid 50s. Depending on how quickly cloud cover departs, parts of western North Dakota could fall below freezing Monday night. But underneath clouds and for sure where precipitation continues, Monday night temperatures will remain above freezing. Lastly, the strengthening surface pressure gradient will cause windy conditions Monday into Monday night. However, model soundings reveal that a lack of diurnal mixing of the boundary layer due to extensive cloud cover could greatly inhibit momentum transfer of 35-45 kt low level winds. It still may be windy enough for an advisory in southwest and perhaps south central North Dakota Monday afternoon and evening, but this may be driven more by sustained winds around 30-35 mph rather than gusts over 45 mph. Surface high pressure is forecast to slide into the Northern Plains Tuesday into Wednesday under a pseudo omega blocking pattern that places the upper level high over eastern Montana. This should lead to a period of drier weather with similar daytime highs that are near to slightly above average but cooler overnight lows that are still near to above average but below freezing. The NBM maintains these temperature trends through the end of the week when ensembles show greater spread in how quickly the upper ridge could break down. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 1230 PM CST Sun Nov 1 2026 Ceilings will lift to IFR and possibly low-end MVFR this afternoon before falling back to IFR/LIFR later tonight. Rain will begin moving into to southwest North Dakota this evening and spread across most of the state by the end of the forecast period. MVFR to IFR visibility can be expected with the rain. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...JJS DISCUSSION...Hollan AVIATION...JJS