


Area Forecast Discussion
Issued by NWS Grand Forks, ND
Issued by NWS Grand Forks, ND
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721 FXUS63 KFGF 121759 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 1259 PM CDT Sat Jul 12 2025 .KEY MESSAGES... - Wildfire smoke will degrade air quality today, with an additional round Sunday. - There is a level 1 out of 5 risk for severe thunderstorms Monday. The main hazards are hail, gusty winds, and flash flooding. && .UPDATE... Issued at 1259 PM CDT Sat Jul 12 2025 Adjusted sky grids for current satellite trends and slowed the exit of smoke as we still have quite a bit of lowered vis well west into ND. Think there will be a break in smoke, but not until later tonight into tomorrow morning based on most recent guidance. UPDATE Issued at 938 AM CDT Sat Jul 12 2025 Visibility from a mix of smoke and fog over parts of west central MN continues to improve, and webcams show coverage is very patchy and not impacting travel much. Adjusted cloud cover up across portions of our eastern counties, and will continue with smoke mention as poor air quality continues. UPDATE Issued at 722 AM CDT Sat Jul 12 2025 Not much change since last AFD issuance. Morning daylight reaffirms widespread smoke across the region, with additional smoke within western ND progged to trek eastward today. Fog has mixed with smoke in some locations like portions of west-central Minnesota to create isolated pockets of dense fog/smoke. However, there are no indications of impacts to travel conditions via webcams and traffic data. Thus, thinking the scenario mentioned in the Discussion portion of the AFD of severely reduced visibility will not come to fruition. && .DISCUSSION... Issued at 417 AM CDT Sat Jul 12 2025 ...Synopsis... Upper level shortwave trough axis resides over the Northern Plains, with post-frontal air mass filled with wildfire smoke over the region. The shortwave trough will continue to migrate eastward into the Upper Midwest and western Great Lakes region today followed by generally northwest flow aloft. This will continue to advect continental air mass originating within Canada, bringing additional wildfire smoke Sunday. Additional details on wildfire smoke and associated impacts found below. Flow then turns more zonal as large upper low over the Hudson Bay develops early next week. This will promote entrance region upper jet dynamics to overspread the High Plains, promoting lee troughing at the surface. This also will promote moisture return from the south into the Northern Plains and Upper Midwest along with increasing instability and frontal development. With forcing for ascent increasing within the region via aforementioned dynamics and frontal development, chance for showers and thunderstorms increases Monday and Tuesday. Increased instability and flow aloft will introduce the potential for strong to severe storms during this timeframe over the Dakotas into Minnesota. More details on this found below. As the Hudson Bay low develops further, there will be a tendency for cooler, continental air mass to intrude over the region. Ensemble guidance like ENS EFI is noting on higher probabilities of below average temperatures between Wednesday and Friday. Lows are currently forecast into the 40s at some locations already. Drier conditions will also accompany this set up, as well as additional chance for more wildfire smoke to infiltrate the region. ... Wildfire smoke today and Sunday ... Current visibilities and AQIs indicate very dense smoke still over the region. VIIRS Day Night Band overnight pass also shows smoke over the Dakotas into Minnesota. This will continue to be the case today with gradual migration of smoke from west to east. Smoke guidance hints at a brief reprieve in near surface smoke tonight into early Sunday before another bout of smoke behind a secondary cold front moves back into the region. Areas like northern Red River Valley into Minnesota are relatively more favored to see smoke impacts than other locations as suggested by available smoke guidance. Smoke is forecast to continue to be thick enough to increase risk of adverse health effects to all populations today and Sunday. Smoke may mix with fog early this morning to further decrease visibilities, perhaps becoming dense at times less than half a mile. It is unclear just how reduced visibilities will become. While low in confidence, cannot rule out smoke mixing with fog to create locally severe reductions in visibilities, with visibility near zero. Should this occur, this would pose significant potential impact to travel conditions. ... Potential severe storms Monday ... There is an emerging confidence in potential for severe storms Monday. AI guidance like NCAR`s Pangu and Fengu Convective Hazard Forecasts both highlight increased probabilities above 15% within portions of North Dakota into Minnesota Monday. While the Storm Prediction Center highlights central ND into Devils Lake basin with a level 1 out of 5 risk for severe storms, confidence is low in location of severe storms due to important synoptic and mesoscale details remaining uncertain. Moderate to strong instability appears likely to build south of a developing frontal boundary somewhere within North Dakota into northern or central Minnesota. This coupled with sufficient shear and increased lower level flow will allow for main hazards to currently favor hail and gusty winds (although to what degree remains uncertain). Additionally, heavy rainfall leading to flash flooding is possible as well. Current modeled guidance presents large swath of 1-2 inches of rainfall over the Dakotas into Minnesota Monday and Tuesday, with low probabilities of 3-5 inches already showing up. Coverage of showers and thunderstorms may be widespread given the slow moving and generally diffuse nature of forcing for ascent in this type of synoptic pattern, but will hinge upon other mesoscale factors like instability, boundary orientation/location, and cloud- bearing flow. This lowers confidence in coverage, location, and amount of rainfall. The Weather Prediction Center currently has a level 1 out of 4 risk for excessive rainfall leading to flash flooding over our region for Monday and Tuesday. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1259 PM CDT Sat Jul 12 2025 Most ceilings are VFR, but smoke from Canadian wildfires continues to keep many visibilities in the 3-6SM range, with some locations even down to 2SM at times. There should be a bit of a break in the surface smoke sometime tonight or tomorrow morning, but a lot of uncertainty as to exactly when. For now have a break late tonight into tomorrow morning from west to east, then another round of smoke towards the end of the period. Winds gusting from the northwest around 20 kts this afternoon will decrease and become more southwesterly around 10 kts by morning, then back to the northwest for the more western airports by 18Z Sunday. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...CJ/JR DISCUSSION...CJ AVIATION...JR