FXUS63 KBIS 140245 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 945 PM CDT Thu Jun 13 2024 .KEY MESSAGES... - There is a Marginal Risk (level 1 out of 5) for severe thunderstorms Friday evening, specifically across the southwestern portions of the state. Chances for showers and thunderstorms are 60% across the area. - An active pattern begins on Friday and will continue through the weekend into next week. Showers and thunderstorms are likely to be on and off, although it does not seem like any one day will be a washout. - There is also a Marginal Risk (level 1 out of 5) for severe thunderstorms Saturday evening and overnight, covering most of western and central North Dakota. The chance for showers and thunderstorms is 70% across the area. - 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. && .UPDATE... Issued at 944 PM CDT Thu Jun 13 2024 Quiet night continues. Clouds and winds have fully died and calmed down. No updates needed. UPDATE Issued at 634 PM CDT Thu Jun 13 2024 Not a lot to update as high pressure is causing nothing to happen. Diurnal clouds up north are starting to die, as well as the wind. && .DISCUSSION... Issued at 329 PM CDT Thu Jun 13 2024 Across western and central North Dakota, mostly quiet weather is being observed, with mostly clear skies in the south, partly cloudy skies in the north, and breezy northwesterly winds for the entire area. Surface high pressure across Montana continues to expand east into western North Dakota, while an upper level ridge across the Rockies slowly builds east into the northern Plains. A trough digging into the Great Lakes region to our northeast has provided enough forcing to develop some scattered showers across the southern Canadian prairies and northern Minnesota. As a result, the northeastern portion of our area, particularly centered around the Turtle Mountains, currently has a low (15 to 25%) chance for some showers and potentially a thunderstorm through the next couple hours. This trough will move east heading into the overnight hours, decreasing the chances for any precipitation, as well as decreasing winds to light and variable. Daytime highs will be in the 70s to lower 80s, while overnight lows are forecast to be in the upper 40s to lower 50s. As the aforementioned ridge moves east through Friday, a cutoff low near the southern coast of California is expected to meander across the Rockies and slide northeast towards the central and northern Great Plains. The resulting surface low and attendant warm front are both expected to form and move east across southeastern Montana, northern Wyoming, and the western Dakotas. The SPC has brought the Marginal Risk (level 1 of 5) back into southwestern North Dakota for Friday, as ample instability and deep layer shear overlap with the forcing due to the approaching shortwave trough to our southwest. High-res deterministic guidance suggests MLCAPE values near 1500 J/kg with 0-6 km shear approaching 50 kts in a narrow corridor across our southwest, which could certainly support a few strong to severe storms. However, the forcing required to get these storms going seems to be slightly displaced from our area and rather short lived, with current CAMs suggesting a brief period where strong storms form and move east, before quickly dissipating as they enter an unfavorable, stable environment. Otherwise, chances for precipitation (ranging from 40 to 60%) will continue to expand from southwest to northeast across the area into Friday night, where showers and thunderstorms will remain possible. The overnight hours are not expected to see any strong to severe storms. Highs on Friday are forecast to be in the 70s and 80s, with overnight lows near 60. An upper level trough across the Pacific Northwest is expected to strengthen and move east through Friday, putting North Dakota under southwesterly upper level flow by Saturday morning. Surface flow ahead of this trough is expected to be southerly, which is also expected to advect plenty of moisture north, with dewpoints on Saturday currently forecast to reach into the mid 60s. The developing surface low pressure system and attendant cold front are then expected to sweep across the northern Plains from the west, helping bring about continued chances for precipitation. Heading into the late evening hours, deterministic guidance suggests a large area of MLCAPE around 2000 to 2500 J/kg, paired with 0-6 km shear in the 40 to 50 kt range. As a result, the SPC has continued to advertise a Marginal Risk (level 1 of 5) for strong to severe storms across most of western and central North Dakota for Saturday. Due to the front moving through later in the evening, the current expectation is that the severe threat will largely be late evening and into the overnight hours, bringing about the threat of nocturnal severe thunderstorms during a summer weekend. Outdoor safety during this event, especially for outdoor campers, will likely be a priority for our messaging, and we will continue to closely monitor how the forecast for this evolves. Outside of the severe threat, chances for showers and thunderstorms (ranging from 40 to 80%) cover our entire area through the day, with the highest chances in the north. Saturday is also expected to be the warmest day of the forecast period, with widespread highs in the 80s, potentially reaching the 90s in the southwest. The southwesterly flow aloft is expected to then continue into next week, carrying near daily chances for showers and thunderstorms. Tuesday appears to be the day with the highest chances for precipitation, with chances ranging anywhere from 50 to 80% across a wide area, and highest values focused across the west. Sunday marks the beginning of a cooling trend, with highs on Tuesday dipping largely into the 60s. Winds on Sunday may be a bit breezy as well, mostly across the west. Beyond this point, the synoptic pattern is still a bit up in the air, with large disagreements between models. Current ensemble guidance suggests some warming heading into the second half of next week, with continued chances for precipitation each day. Temperatures will largely depend on the strength of an upper level trough to our west, building against a ridge across the Great Lakes to our east. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 634 PM CDT Thu Jun 13 2024 VFR through the period with winds calming down by sunset. Winds will then gust up to 30 knots Friday again. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Smith DISCUSSION...Besson AVIATION...Smith