FXUS63 KBIS 141929 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 229 PM CDT Fri Jun 14 2024 .KEY MESSAGES... - There is a Marginal Risk (level 1 out of 5) for severe thunderstorms this afternoon through tonight, specifically across the western portions of the state. - There is a Slight Risk (level 2 out of 5) for severe thunderstorms late Saturday afternoon through Saturday night, covering most of western and central North Dakota. - There is a Marginal Risk (level 1 out of 5) for severe thunderstorms Sunday across far southeastern portions of the state. - High temperatures are forecast to peak in the 80s on Saturday (potentially reaching the 90s in the southwest), with a gradual cooling trend through the first few days of next week. - Periodic showers and thunderstorms are expected next week, with the best chances Monday night with precipitation chances ranging from 60 to 80 percent across the state. && .DISCUSSION... Issued at 129 PM CDT Fri Jun 14 2024 The main forecast challenge is the potential for severe weather this afternoon through this weekend. Presently, a transitory ridge is passing through the central Dakotas with a weak trailing shortwave analyzed over eastern Montana towards western South Dakota. This shortwave and associated WAA will help generate showers and thunderstorms this afternoon possibly lingering into the overnight hours. Instability will become moderate in the west with CAPE values around 1000 to 2000 J/kg, especially in the southwest, as Gulf moisture advects into the area. Shear is on the lower end at around 30 to 40 kts, but it's enough for a few severe thunderstorms to develop. One of the biggest limitations to potential severe weather is that capping is quite strong in the west. While it is progged to deteriorate, there is some question as to whether it will break in time or not. As a result, there is a window for severe weather mainly in the west this afternoon and early evening, but it's also possible storms will stay sub- severe. The primary threats are hail up to the size of ping pong balls and 60 mph wind gusts. A bigger severe weather threat is possible on Saturday. Unlike today where Gulf moisture is primarily advecting into western ND, Gulf moisture will be present over most of the state. This will result in mixed layer dewpoints approaching 60 degrees, thus creating ample instability over much of the area. In the late afternoon, wind shear looks marginal (though enough) along and south of I94, while areas further north of I94 and west of Highway 281 are progged to have strong shear in excess of 50 kts of 0 to 6 km bulk shear. Moderate instability and strong shear values migrate eastward through Saturday night. The primary forcing mechanism looks to be a moderate shortwave along with associated surface cold frontal boundary, which looks to begin sliding through the area in the late afternoon. This will result in severe weather potential in the later afternoon, through the evening, and potentially into the early overnight hours. In regard to potential hazards for Saturday, shear vectors are generally parallel or between parallel and perpendicular. Overall, this favors a more clustered event that may become linear. However, a few discrete supercells are possible earlier on. With any discrete supercells, hail of two inches or greater is possible. There remains a very conditional brief tornado threat window should any discrete cells develop. Otherwise, in a more disorganized cluster, threats include wind gusts up to 70 mph and hail up to ping pong ball size. Any hail threat will diminish as storms become more linear leaving a primary threat of wind gusts up to 70 mph. Isolated gusts up to 80 mph are not out of the question. Beyond Saturday, breezy to windy conditions are possible in the north and west, and especially the northwest itself, as the pressure gradient tightens between low pressure to the north and high pressure to the southwest. One point to this is that with strong pressure rises and moderate CAA progged in deterministic models at this time; winds may wind up being stronger than presently forecast. Otherwise, expect periodic showers and thunderstorms with severe weather not out of the question Sunday in the far southeast CWA, and Monday in the eastern CWA. The highest confidence for widespread precipitation next week is Monday through Tuesday afternoon, and especially Monday night, as deep low pressure originating in Wyoming moves through the central/northern Plains. As a result, the entire forecast area is already forecast for a 60 to 80 percent chance of seeing showers and thunderstorms. This low pressure will also bring a return of cooler temperatures. Though exact values will be ironed out in the future, the majority of the forecast area is favored to see highs return to the 60s Monday through Wednesday. A gradual warming trend is then favored for the latter half of next week. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1258 PM CDT Fri Jun 14 2024 VFR ceilings and visibility are present to start the TAF period. Shower and thunderstorm chances will begin entering western North Dakota this afternoon and progress eastward through the evening and overnight. A few severe thunderstorms are possible this afternoon and early evening primarily in western North Dakota. The primary threats are quarter size hail and erratic winds up to 60 mph. MVFR ceilings are also possible in the south central, including KJMS, late tonight through Saturday morning. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Telken AVIATION...Telken