622 FXUS63 KBIS 111131 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 631 AM CDT Fri Apr 11 2025 .KEY MESSAGES... - Critical fire weather conditions are expected today across western and much of central North Dakota. A Red Flag Warning remains in effect from late this morning through early evening. - Temperatures will peak today, then will start to trend cooler on Saturday, turning colder Sunday and Monday. Widespread medium to high chances (50-80%) for rain expected Saturday night through Sunday night, ending on Monday. Some snow may mix in Sunday night through Monday morning. - Temperatures trend warmer after Monday of next week, along with mainly dry weather conditions. && .UPDATE... Issued at 627 AM CDT Fri Apr 11 2025 No changes. Dense fog continues to remain to our east, with far eastern areas of the James River Valley perhaps at times seeing visibility below a mile. Web cam imagery do not support headlines. See below for further forecast discussion for the forecast period. && .DISCUSSION... Issued at 420 AM CDT Fri Apr 11 2025 Currently, upper level ridge developing east into the Northern Plains this morning, with surface high pressure to our southeast and developing low pressure across the lee of the Northern Rockies. Lack of wind and lingering boundary layer moisture over eastern areas of the state contributing to areas of fog there this morning, including eastern areas of the James River Valley. Dense fog is currently mainly east of the James Valley, and looking at web cams thus far visibility looks decent enough to hold off on any fog headlines. Will continue to monitor. Upper ridge axis pivots east over the Dakotas today, with the aforementioned lee sfc trough developing into eastern MT this morning, then across the far western Dakotas this afternoon. Increasing southerly flow results, with sfc winds increasing west to east as we lose the morning inversion. Peak gusts within the boundary layer look roughly 25-30kts, so basically unchanged from what models previously indicated. WAA will also result, with highs well in the 70s west and central, and still forecast around 80F in the southwest. As we mix, sfc dewpoints are favored to drop into the low 20s and upper teens along and west of Highway 83, with resultant min RH values as low as 10% from southwest ND north/northeast into parts of the north central. Some models (RAP and HRRR included) advertise upper single digit RH values, which is very possible. All told, Red Flag conditions are still expected late morning through early this evening for western and much of central North Dakota. Main change from the previous forecast was to lower RH values a tad, and opted to add Bottineau county to the warning. See fire weather discussion below for additional details. Ridge flattens tonight as a potent S/WV slides east across southern Canada, transitioning flow aloft to quasi-zonal. Another embedded strong S/WV will approach the Northern Rockies during the day Saturday, then closes off as it continues east- southeast across the Dakotas Saturday night through Sunday night. Lead embedded impulses will bring some light precipitation to the west and parts of central ND tonight and during the day Saturday, with the main forcing arriving Saturday night into the day Sunday. This is when we expect widespread rainfall chances, with the heavier amounts focused across northern areas of west/central ND where upper level forcing coincides with low/mid level frontogenesis near an inverted sfc trough axis. Upwards to an inch of much needed moisture will be possible there. Lighter QPF is depicted farther south, around a quarter of an inch far southwest and south central, with southern areas of the James Valley the lowest (a tenth of an inch or less). This initial upper low moves off to the east Sunday night, followed by another embedded S/WV in northerly flow aloft during the day Monday. Resultant weather will see precipitation chances and coverage decreasing Sun night, with continued scattered showers possible through the day Monday. In addition, colder air pulled in behind the departing initial upper low, will bring a chance of some snow mixing in with any lingering showers Sunday night through Monday AM. At this time, not expecting any impacts with this. Along with colder temperatures and widespread precipitation, winds will increase Sunday and continue through Monday as gradient forcing increases. Wind headlines are possible. Flow aloft is favored to be northwesterly after Monday, as an upper level ridge attempts to rebuild over the western CONUS. Overall, we are favored to see temperatures trend warmer after Monday, with initially mainly dry weather conditions. Embedded waves with the flow aloft may bring precipitation chances at times next week, but for now the uncertainty is elevated with NBM only generating slight chances for us mid to late next week. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 627 AM CDT Fri Apr 11 2025 VFR conditions are expected with occasional mid to high clouds moving across the region. Winds will become southerly this morning, before increasing and becoming gusty today. Winds across western North Dakota will transition to more westerly later in the afternoon. && .FIRE WEATHER... Issued at 420 AM CDT Fri Apr 11 2025 Critical fire weather conditions are expected today due to dry and windy conditions. Minimum relative humidity is forecast to drop as low as 10 percent in the southwest to around 14 to 20 percent from Renville/western Bottineau down to McIntosh county. The strongest winds are forecast to by in the central portion of the state with sustain winds from the south around 20 to 25 mph and gusts up to 35 mph. The southwest will see the lowest minimum relative humidity, however their winds may remain around 15 to 20 mph and will weaken after 21Z. Due to the continued dry conditions, fires that can start may rapidly spread and become difficult to suppress. Winds will decrease this evening along with RH values recovering to over 30 percent by midnight. && .BIS WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from 11 AM CDT /10 AM MDT/ this morning to 9 PM CDT /8 PM MDT/ this evening for NDZ001>004-009>012-017>022- 031>036-040>047-050. && $$ UPDATE...NH DISCUSSION...NH AVIATION...NH FIRE WEATHER...NH