Area Forecast Discussion
Issued by NWS Bismarck, ND
Issued by NWS Bismarck, ND
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180 FXUS63 KBIS 061756 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 1256 PM CDT Sat Jul 6 2024 .KEY MESSAGES... - Scattered showers and thunderstorms (30 to 60%) are again expected today across western and central North Dakota. - One more day of shower and thunderstorm chances (30 to 60%) on Sunday, with the better chances east. - A gradual warming and drying trend is still expected for next week, with temperatures above normal by the end of the week. && .UPDATE... Issued at 1227 PM CDT Sat Jul 6 2024 Early this afternoon, an upper low continues to spin along the North Dakota/South Dakota border over the south central. This has kept shower and thunderstorm activity going over the James River Valley. We continue to see new development on the western edge of the precipitation shield in the wake of outflow and we will have to watch the heavy rain potential with this activity if we keep redeveloping over areas where heavy rain has already fallen. The other thing to keep any eye on through the afternoon is the potential for another round of potential weak funnels/landspouts. Background surface vorticity from the upper low, strong low level instability, and low shear all point to a favorable environment; especially along the ongoing convection across the James River Valley where the non-supercell tornado parameter is already showing values up to 3. UPDATE Issued at 947 AM CDT Sat Jul 6 2024 No major changes were needed for this update. The heaviest lightning activity remains generally in the Devil`s Lake Basin and portions of the James River Valley. This activity will slowly continue moving north northeast over the next couple hours before exiting into the the Grand Forks forecast area. We are still expecting numerous hit or miss showers and storms to form once again this afternoon. UPDATE Issued at 624 AM CDT Sat Jul 6 2024 Two areas of showers/thunderstorms continue early this morning. Line of storms continues to flare up along a sfc trough/boundary as forcing associated with a mid level wave interacts across the James River Valley. Second area is associated with the base of the wave, which likely is closed off into a 700-500mb low, with showers and at times thunderstorms arcing around the circulation over south central into parts of southwest North Dakota. Both areas will migrate east with time this morning. Could see convection persisting over south central ND through much of the morning based on model projections of the low`s movement. A few lighter returns elsewhere within the larger mid level trough over the region. POPs and other hourly weather elements were updated based on latest observations and trends. UPDATE Issued at 504 AM CDT Sat Jul 6 2024 Quick update to expand POPs over the James River Valley. Convection starting to flare up here along the sfc boundary and in response to the incoming wave. && .DISCUSSION... Issued at 350 AM CDT Sat Jul 6 2024 Currently, mid level S/WV continues to develop easterly into the Dakotas, centered over southwest North Dakota, with a sfc trough extending from south central into northeastern North Dakota. Showers and a few isolated thunderstorms persist along the sfc trough, with an arc of showers wrapping around the main circulation area of the mid level wave over my southwest. Expect the activity along the sfc boundary to slowly diminish early this morning as the boundary washes out/moves farther east. Precipitation near the center of the mid level wave should persist and develop eastward this morning as this feature continues east along to slightly south of the ND/SD border. While MLCAPE is decreasing, enough elevated instability present to maintain thunder wording. For today, expect another day of scattered showers and thunderstorms with an unsettled atmosphere and decent instability once again present over the local region. Shear remain minimal so the threat for severe weather remains very low. Mean flow aloft is weak today with a mid level trough over the Northern Plains, so some potential for a few heavy rainers with expected slow moving convection. Non-supercell Tor parameters (NST) is also similar to the past couple of days, so wouldn`t be surprised to see more funnel cloud reports during the daytime. Showers and isolated storms will continue into this evening, before diminishing later tonight as we lose heating. Sunday looks like another active day, though we start to see the better shower/storm coverage pushing more to the east as our persistent trough sets up more over the Western Great Lakes region and eastern Dakotas, in response to a strong upper level ridge developing onshore over the west coastal region. The aforementioned strong upper level ridge moving into the western CONUS will continue to slowly nudge eastward through next week. Ensemble blends continue to keep us in a north/northwest flow pattern both Monday and Tuesday, and sure enough NBM has now come in with some low POPs over my far east both days. Most of our area will remain dry, though any wave within the flow aloft could fire off diurnally driven convection. Temperatures are still favored to slowly warm through next week, finally approaching seasonal normal values (low/mid 80s) by the middle of the week. Once the ridge moves into and across the Rockies mid to late next week, temperatures are favored to be above normal and the weather will be mainly dry. High temperatures Thursday - Saturday are favored to be well into the 80s and into the low/mid 90s. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1227 PM CDT Sat Jul 6 2024 For the most part we should see VFR conditions across western and central North Dakota through the period. However, we will see more scattered showers and thunderstorms again through the day, diminishing in the evening. The best chances will generally be north and east, including sites KXWA, KMOT, and KJMS. Due to the hit or miss variety of these storms, will heavily lean on vicinity wording in the forecast for now. The one exception is at KJMS where ongoing showers and storms in and around the area may lead to brief MVFR conditions over the next hour or so. Further west and south (including KDIK and KBIS), shower and storm coverage is a bit more uncertain and will refrain to include precip in the forecast for these sites at this time. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...ZH DISCUSSION...NH AVIATION...ZH