Area Forecast Discussion
Issued by NWS Bismarck, ND
Issued by NWS Bismarck, ND
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077 FXUS63 KBIS 050237 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 937 PM CDT Thu Jul 4 2024 .KEY MESSAGES... - Scattered showers and isolated thunderstorms will continue to diminish through this evening. - The story will be much of the same Friday through Sunday with daily chances (30 to 60 percent) of showers and scattered thunderstorms. The entire day will not be a washout for most, as much of the activity will be of the "hit or miss" variety. - A gradual warming and drying trend is expected to begin next week. && .UPDATE... Issued at 937 PM CDT Thu Jul 4 2024 Convection continues to diminish this evening, although we still have a few areas with persistent lightning, primarily in the Ward and McHenry County areas. There are some showers moving south towards the Bismarck/Mandan area, but hoping those continue to dissipate, and worst case only bring some light rain in the next hour or two. Latest trends and high- res guidance indicate showers and isolated thunderstorms should be completely done across the forecast area by 7 or 8 UTC, although by midnight most locations will not be seeing any additional rain. Freshened up POPs through tonight based on this, and also used latest blended guidance for POPs through the day Friday, with additional hit and miss showers and thunderstorms expected through the day. UPDATE Issued at 643 PM CDT Thu Jul 4 2024 Scattered showers and thunderstorms continue on the northwest side of a deep upper low analyzed in central Minnesota early this evening. The good news is that over the past hour or so, radar returns have begun to noticeably diminish as we lose our diurnal heating. We did update POPs but it is a bit tricky since although there are upstream storms in the southern Canadian Prairies, we aren`t expecting them to last too much longer once they cross into northern North Dakota. Tried to broad brush precipitation chances with the potential trending down through the evening, and especially once we get past midnight. We continue to monitor any localized flooding potential, with multiple reports of heavy rain rates with these storms (at least half an inch of rain in 10 to 15 minutes, for example). The combination of slow-moving storms from limited flow aloft, and occasional areas of training, have caused some concern across areas in the south central as well as northeast of Williston. The expectation is that as the current showers and storms diminish, any remaining flood potential will end across the area. && .DISCUSSION... Issued at 200 PM CDT Thu Jul 4 2024 Western and central North Dakota currently sits under the influence of a broad upper low overhead and an expansive amplified ridge to our west. Cyclonic flow will maintain numerous showers and scattered thunderstorms through the afternoon and into the evening across most of western and central North Dakota. These storms will be your typical popcorn/hit or miss summertime thunderstorms with a skinny CAPE profile and very low shear. However, we have started to notice a bit of a training trend, especially along the line from just southeast of Harvey, down to near Moffit. MRMS estimates we`ve seen anywhere from an inch to 2.5 inches of rain along this line of storms in the past couple of hours. There may be some small hail contamination with a few storms but reports suggest these are efficient rain producers with some rainfall rates of 1 to 3 inches or greater an hour. If sufficient training can maintain itself, a localized flooding environment here could end up materializing through the afternoon. Thus far, MRMS Crest Unit Streamflow has only shown minimal response. Showers and storms will last into the early evening but should start to diminish with the loss of diurnal heating. Lows tonight will be in the 50s under a partly to mostly cloudy sky. The upper low kicks out to the east by Friday morning and low amplitude ridging moves quickly across the state through the first part of the day. A subtle shortwave embedded within the larger western US ridge will approach in the afternoon hours, leading to another thunderstorm environment similar to today with some decent instability but little to no shear. Coverage will be similar, very hit or miss with popcorn convection. Rinse and repeat on Saturday as another compact upper low rides down the western ridge and brings us yet another round of popcorn convection. The western ridge then finally starts to nudge closer to us on Sunday, shifting the best chances of scattered showers and storms to the eastern half of the forecast area. Highs will be in the 70s through Sunday. By Monday, we start to dry out as the ridge continues to approach. This will also help warm temperatures through the week. We start off with highs in the mid 70s to lower 80s on Monday, warming into the 80s and possibly even some lower 90s by mid to late week. NBM temperature spread is very low considering the time frame so it seems like ensembles are in fairly good agreement that this western ridge will be a main driver for our weather pattern next week. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 643 PM CDT Thu Jul 4 2024 Hit or miss thunderstorms will slowly diminish through the evening, expecting to end by around 06Z at all terminals. Severe storms are not expected but the strongest storms may produce locally heavy rainfall and small hail. If a heavier storm moves overhead, brief MVFR to IFR visibilities will be possible. Ceilings are generally VFR at all terminals, although can`t rule out a brief period of MVFR ceilings, especially in areas of precipitation. Winds may become gusty and erratic in and around any thunderstorms. Chances for precipitation return Friday afternoon, and we did include VCTS at KDIK/KXWA during this time with this update. However, precipitation chances/timing late in the TAF period will be similar to today, where it will be scattered hit or miss showers and thunderstorms with low predictability. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Jones DISCUSSION...ZH AVIATION...Jones