Area Forecast Discussion
Issued by NWS Bismarck, ND
Issued by NWS Bismarck, ND
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882 FXUS63 KBIS 200530 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 1230 AM CDT Thu Jun 20 2024 .KEY MESSAGES... - Hit or miss showers (20 to 30 percent) are possible through today. Better chances for showers and thunderstorms (40 to 70 percent) return tonight through Saturday. - A slow warming trend is expected heading into the weekend and early next week, with highs approaching the upper 80s and lower 90s by Monday. && .UPDATE... Issued at 1230 AM CDT Thu Jun 20 2024 No updates to the forecast were needed at this time. Isolated, light radar returns linger over portions of the southwest and north central, with a better band of showers skirting across the northwest. There are some thunderstorms embedded in this line of showers, though they continue to remain outside of our area and have begun to diminish. Otherwise, scattered to broken mid levels clouds continue to filter across the area and winds are generally light out of the north. The forecast remains on track. UPDATE Issued at 909 PM CDT Wed Jun 19 2024 Isolated light radar returns continue over the northern third of the forecast area. Overall, most of these returns are dry (virga), although an occasional light shower or sprinkle is possible under the "heaviest" returns. Nevertheless, these returns continue advancing steadily northeast where they will appear to somewhat diminish due to the Minot radar still being down. A more significant line of scattered showers and general thunderstorms continue in northeastern Montana. These showers and thunderstorms are heading northeast as well and may pass through northwestern ND. However, instability should continue to decrease as the sun sets. Thus, while there may be a few lightning strikes, thunderstorm activity should decrease as well. UPDATE Issued at 633 PM CDT Wed Jun 19 2024 A narrow line of returns rapidly moving to the northeast extends north of I94 from the MT/ND border to west of the Missouri River. However, air is fairly dry and to this point, only brief and non-measurable light rain has been observed. Otherwise, the forecast remains on track. && .DISCUSSION... Issued at 239 PM CDT Wed Jun 19 2024 Surface high pressure is positioned across north central North Dakota, slowly drifting east through the day, as southwesterly flow aloft remains across the Northern Plains. Mostly clear skies and relatively light winds are present across much of western and central North Dakota as a result, with a few fair weather cumulus clouds forming and moving north across the far northwestern corner of the state. As the surface high pressure drifts east, southerly flow across the far western portions of the state will increase enough to provide some low chances for showers later tonight, with the highest chances across the southwest and northwest corners (both roughly 15 to 25 percent). CAMs don`t show much when it comes to these little waves of precipitation, but its certainly a possibility that some areas may see a sprinkle, and possibly even some thunder. Probabilities for anything producing any lightning is near zero, but not completely out of the question. This southerly low level flow continues on Thursday, as cloud coverage and chances for showers slowly increase across the area, from south to north. As such, high temperatures across the south will be tempered just a bit, with values in the upper 60s across the south, ranging to the mid 70s across the north. With the continued southwesterly flow aloft, messy shortwaves embedded within the flow will lead to disorganized showers across the area. PoPs across the the area will be in the 30 to 60 percent range across the southern half of the area, with the highest chances arriving later Thursday night. There will also be a corridor of increased instability just north of the International Border, due to the warmer temperatures up there, which could lead to some isolated thunderstorms near the border. The highest CAPE values are positioned entirely outside of our area, so the chance for these storms are once again rather low. Showers and possible some thunderstorms continue through the day Friday, covering nearly the entire area with at least a 40 percent chance for showers by Friday evening, with the southern half of the area seeing chances from 60 to 70 percent. Thunderstorms are once again possible, given the marginal instability and very pronounced shear, but the instability maximum once again resides just outside of our area, this time to our southeast. The SPC has outlined much of eastern South Dakota in a Marginal Risk (level 1 of 5) for severe thunderstorms, but this risk stops right before it reaches the North Dakota border, near the southern James River Valley region. We will continue monitoring this situation in case some of the ingredients needed for severe weather begin to shift north. Regardless, much of the area will see a slight chance for some thunder Friday evening. Saturday will see the beginning of a drying trend, as an upper level trough to our northwest begins to shift eastward, placing North Dakota under more of a zonal flow aloft. Model ensembles are still not very tight from this weekend onward, but the general consensus is that this weekend and the start of next week will be mostly dry, with weak embedded impulses bringing low chances for precipitation nearly daily (with chances around 15 to 30 percent). Upper level ridging to our west may begin to slide east through Sunday and Monday, with NBM high temperatures suggesting the possibility for widespread highs in the upper 80s to lower 90s by Monday. NBM spreads for Monday in particular are rather low, which indicates increased confidence that pretty warm temperatures are expected that day. These spreads then begin to increase quite a bit from Tuesday onward. Despite the spreads and uncertainty increasing during that period, the general trend of temperatures gradually decreasing is prevalent. The continued mostly zonal westerly flow aloft is expected to remain through the middle of next week. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1230 AM CDT Thu Jun 20 2024 VFR ceilings and visibility are expected at all terminals at the start of the TAF period. Winds will generally be weak and out of the south, though may become modestly breezy over portions of the west this afternoon. MVFR ceilings and chances for showers will begin to push into southern North Dakota through this afternoon and evening, mainly impacting KBIS and KJMS and potentially KDIK. Showers will also be possible across the west, though there is not enough confidence to add it to the KXWA terminal at this time. Some isolated thunderstorms will also be possible late this afternoon through the evening. Chances for showers, thunderstorms, and MVFR to LIFR ceilings will become more widespread beyond the end of the 06Z TAF period. Occasional MVFR visibilities and gusty winds are expected where showers do fall. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Adam/Telken DISCUSSION...Besson AVIATION...Adam