992 FXUS63 KBIS 170836 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 336 AM CDT Thu Apr 17 2025 .KEY MESSAGES... - 60 percent chance for rain tonight through Thursday southwest through central. - Rain may mix with or change to snow in the southwest late tonight through early Thursday morning with some light accumulations possible southwest. - Windy and colder Thursday and Friday with highs mainly in the 40s. The strongest winds will be on Thursday in the James River Valley. - Trending warmer for the weekend and the start of next week. && .DISCUSSION... Issued at 208 AM CDT Thu Apr 17 2025 Currently, low pressure is situated over northern Manitoba with an associated cold front extending south through the eastern Dakotas with another surface low situated over southern South Dakota. In the upper levels, an upper low was dropping south through the northern Rockies. A few additional impulses were rotating around the northern Manitoba low. Today, the Canadian Low and the Northern Rockies low will undergo increased shear as strong upper level ridging builds over the eastern Pacific and into western Canada. This positively tilted upper trough will propagate southeast through our local area today and into this evening. The ongoing and early morning precipitation continues to under perform, mostly due to a lack of moisture. Last night we mentioned the strong FG forcing that was indicated over southwest into central ND. This continues to be the case. In fact currently an area of convection was located over Emmons county, within an area of strong 850mb FG forcing and steep mid-level lapse rates. Would not be surprised to see this weak elevated convection linger a while longer as it lifts northeast, north of the surface cold front. Back over southwest ND, strong 700mb FG forcing is producing some light precipitation. Latest ob from Baker MT is indicating light rain and the latest Bowman radar loop is showing a nice band of higher reflectivities from southwest of Baker, northeast towards Fairfield and Killdeer. Additional bands look to be possibly developing south of this. Unfortunately with a lack of moisture, precipitation has been slow to develop. Overall, the qpf trend continues to decrease with the latest qpf showing up to around 15 hundredths of an inch in the southwest and lesser amounts (generally less than a tenth of an inch) extending east through south central ND. Still can`t rule out a rain/snow mix or a change over to snow in the far southwest early this morning, but any impacts would be minimal. In general, precipitation in the southwest is expected to push east northeast into central ND this morning (associated with the mid level FG forcing) and another area from the far southwest/south central into the James River Valley (associated with the low level FG forcing). With a lack of an entire column of moisture neither is expected to produce impressive qpf amounts (as noted above). By this afternoon, any precipitation is expected to be mainly along the South Dakota border. It will be quite a bit cooler today with highs mainly in the mid 40s to mid 50s with a brisk northerly wind. Tonight and Friday, the increasingly sheared upper trough drops southeast through the forecast area. Although surface high pressure will be situated over the area, there looks to be enough mid-level support to produce some isolated shower activity. Cams are indicating some light shower activity dropping south into northern portions of the forecast area tonight as well as some isolated to scattered shower diurnally driven activity on Friday. The latest NBM is not doing a good job picking this up due to the widespread variability of the CAMS with only little or no significant qpf. Will carry a mention of isolated rain/snow showers tonight and Friday. Due to the light nature and the low predictability in timing/placement impacts will be minimal. Breezy conditions are expected to continue Friday, especially over southern and eastern portions of the forecast area. Highs will be mainly in the 40s. After a cold start to the weekend Saturday morning, with lows mainly in the 20s, we warm into the 50s, with generally light winds. Sunday will be even warmer, with mainly 60 degree readings expected, and just a little more wind. A series of impulses tracking through a mean northwest U.S. trough will bring on and off chances for showers and maybe even a few thunderstorms early to mid week next week, with seasonable temperatures in the 50s and 60s. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1208 AM CDT Thu Apr 17 2025 An area of light rain will spread from southwest to northeast ND through the overnight hours. Rain may mix with or change to snow in southwest around 12 UTC Thu. Expect mostly VFR ceilings through the period. Perhaps a period of MVFR ceilings/vsbys in the southwest this morning, and also over the James River Valley, including KJMS. Northerly surface flow expected across western and central ND today generally 15 to 25 knots, diminishing after 00Z Friday. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...TWH AVIATION...TWH