102 FXUS63 KBIS 160930 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 430 AM CDT Thu May 16 2024 .KEY MESSAGES... - Isolated to scattered showers and thunderstorms today. A few stronger storms are possible with small hail and locally gusty winds this afternoon and evening. - Isolated severe storms are possible Friday afternoon/evening. The main threat will be damaging winds up to 65 mph. - Warming trend through Friday, then a cooldown with breezy to windy conditions Saturday. - Daily chances for precipitation continue through the weekend and into early next week. && .DISCUSSION... Issued at 153 AM CDT Thu May 16 2024 Currently, a weak pressure pattern was situated over western and central North Dakota, behind an exiting low pressure system over Minnesota. Skies were clear to partly cloudy across a good portion of central ND, with mostly cloudy skies in the west. Under the clear skies some areas of fog have developed, mainly over the south central with some patchy dense fog along and east of the Missouri River south of Bismarck and into north central SD. Aloft, a broad northwest upper flow was situated from British Columbia Canada and the Pacific northwest across the Rockies and into the Northern Plains. Numerous shortwaves were propagating through the mean northwest flow pattern. For today we expect a warmer day than Wednesday, possibly around 20 degrees warmer in some areas of the south central into the James River Valley. Winds should also be on the light side generally varying from west to south around 12 mph or less. Expect a mix of sun and clouds today with hit and miss showers and isolated thunderstorms. As for the risk of storms, there is currently a weak shortwave over central ND producing some mid-level clouds and little if any precipitation. Another was was situated along the ND/MT border and is forecast to drop southeast this morning and could produce an isolated to scattered shower west into south central. A cluster of showers and isolated thunder was also dropping southeast from southwest Saskatchewan toward northeast Montana. Currently most of the latest CAMS have this activity breaking up as it moves into northeast MT and towards ND. Will have to see how it trends the next few hours and may have to include some morning shower activity northwest. A shortwave approaching Montana will approach the local area later today. Between the morning shortwaves and this trailing shortwave will be a period of shortwave ridging. Under this ridging we will become slightly unstable this afternoon/early evening with ML CAPE on the order of 500-1000 J/KG with decent bulk shear of 25 to 35 knots. Some limiting factors will be the aforementioned upper level ridging and limited low level moisture, especially west of the Highway 83 corridor. However, there could be a few stronger storms with small hail and locally gusty winds. Overall though the potential for severe storms looks pretty low and SPC has continued with a general thunderstorm risk. Later in the evening as another wave tracks along the International border, more general showers and thunderstorms with a greater areal coverage may track along and north of the Highway 2 corridor. A digging upper level trough from southwest Canada into the Pacific northwest will transition our northwest upper flow Today, to a southwest upper flow on Friday as and upper level low develops over the Canadian Prairie Provinces and a strong shortwave tracks around the base of this low from the Northern Rockies into the Northern Plains. This will set the stage for another round of thunderstorms Friday. A surface frontal boundary dropping south from the aforementioned Canada low, looks to be situated over central ND around 00 UTC Saturday. Along and behind this boundary we have strong bulk shear of 40-60 knots. Ahead of the front we once again become slightly to moderately unstable with ML CAPE of 500-1500 J/KG. There is stronger capping the farther east you go ahead of the front and earlier in the afternoon, but capping becomes weaker just ahead of the front late afternoon/early evening. Point sounding in the vicinity of the front late Friday afternoon show long straight line hodographs with nearly 1500 J/KG of CAPE and inverted V shaped high based soundings with strong DCAPE. The bulk shear looks to be nearly parallel to the frontal boundary which would yield quick upscale growth with fast storm motions. Therefore damaging winds look to be the greatest threat, with possibly some marginally severe hail early within any storm development. The severe threat quickly diminishes behind the frontal boundary as low level flow becomes unfavorable. Another shortwave moving through the mean flow tracks through the forecast area late Friday night into Saturday morning bringing some scattered shower activity, followed by stronger winds behind the wave that continue through Saturday. Saturday will also be cooler with highs mainly in the 60s. The Canadian upper low hangs around through the weekend and into early next week, keeping an active weather pattern over our area. After the cool shot Saturday we rebound slightly Sunday but through the middle of next week temperatures remain near mid May normals with highs in the 60s and lows in the 40s. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1225 AM CDT Thu May 16 2024 MVFR cigs/vsby at KJMS to begin the 06Z TAF period. Latest satellite imagery shows MVFR cigs extending west through Stutsman county but does show the western edge of the clouds eroding/progressing east. It's uncertain as to if MVFR clouds will exit with a period of clear skies before possible fog develops, or ceilings gradually lower on the edge of the stratus and JMS transitions to lower cigs, remaining overcast. For now kept lowering MVFR ceilings and VSBY lowering form MVFR to IFR, through mid morning. Elsewhere, a band of showers has moved through KXWA and approaching KDIK but looks to be dissipating quickly as it moves east. Through the day a hit or miss shower can not be ruled out anywhere, but uncertainty is too high through much of the day to even include a VCSH. Did include a VCSH at KXWA and KMOT later in the day and this evening with a better chance of showers moving across the north. Winds are variable from generally south to west through the TAF period at 10 knots or less at all sites. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...TWH AVIATION...TWH