484 FXUS65 KTFX 060249 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 849 PM MDT Sat Jul 5 2025 .KEY MESSAGES... - A few stronger thunderstorms this afternoon, mainly over the eastern plains. - Another opportunity for a stronger thunderstorm or two across the Hi-Line Sunday afternoon. - Trending warmer and drier early next week. && .UPDATE... 8:45 PM UPDATE Slight adjustments were made to the precipitation chances and winds in the next 24 hours based on updated NBM guidance. Otherwise, no major changes to the going forecast. -thor 6:20 PM UPDATE Given that the main threat for severe weather has ended for Fergus and Blaine counties, the severe thunderstorm watch has been cancelled. A couple thunderstorms are expected to continue their way across Fergus county with the potential for some stronger wind gusts. However, gusts over 50 mph are not expected from here on out. Additionally, given the latest trends, the chance for fog was added to the forecast for tonight. At this point in time, widespread dense fog is not expected so no products are needed at this time. However, motorists should be prepared for sudden reductions in visibility during the overnight and early morning hours. -thor && .DISCUSSION... /Issued 624 PM MDT Sat Jul 5 2025/ - Meteorological Overview: Troughing well ahead of a building ridge across the eastern Pacific will continue to support showers and thunderstorms this afternoon and evening as it marches eastward out over the plains. Areas in and adjacent to Blaine/Fergus county appear to have the greatest risk for a strong to severe thunderstorm this afternoon. The best thermodynamic and kinematic environments overlap here, which will yield an initial large hail threat (Wind to a lesser extent) before storms move east of the area later this afternoon and evening. Given the proximity of the mid-level low over portions of the Hi-Line and vicinity this afternoon, a brief funnel from a more robust thunderstorm does not seem unreasonable. The building ridge shifts eastward toward the west coast heading into Sunday. One final wave cascading through the building ridge clips the Hi-Line Sunday afternoon, which will yield at least a low- end chance for thunderstorms. Forecast soundings show an environment marginally conducive to supercells straddling the Canadian border within the West-Northwest flow aloft. High resolution guidance is split as to whether a rogue supercell or two will form north/south of the border, with each solution seeming plausible at this point. The ridge finally builds in for early this upcoming week, which will promote a drying and warming trend through mid week or so. A more zonal to slightly southwesterly flow develops briefly mid to late week, which will re-introduce low-end shower and thunderstorms chances. Ensembles favor another period of ridging then attempting to build in toward next weekend, though specifics become murky at that range. -AM - Forecast Confidence & Scenarios: The point of greatest uncertainty in the next few days is where exactly a stronger thunderstorm or two develops Sunday - whether along the Hi-Line or further north into Canada. Guidance is split between these solutions, and we will likely need to resolve finer scale details that will play out through the day today before getting a better idea as to where the greatest risk will ultimately settle Sunday. If a rogue supercell or two were to form near the Hi- Line, large hail and gusty winds will be the greatest concern. Otherwise, confidence is high in a warming and drying trend heading into next week with a brief cooldown mid-late week as precipitation chances sneak back into the forecast. Larger spread exists in the temperatures forecast into next weekend, as ridging attempts to build in. A ridge that builds in faster/stronger would result in a quicker warming trend while a slower to build/lower amplitude ridge would favor slower warming. -AM && .AVIATION... 06/00Z TAF Period A few showers and thunderstorms will be near KHVR, KLWT and KWYS initially this evening, with these moving east of the area by 04z. Otherwise, VFR conditions prevail across the area with decreasing clouds overnight, though clearing may provide some potential for patchy fog near the KWYS and KHVR terminals. Surface winds primarily from the north to northwest this evening will decrease overnight with generally light west to southwest winds Sunday morning, turning more northwesterly again Sunday afternoon. Hoenisch Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PRELIMINARY POINT TEMPS/POPS... GTF 50 81 52 86 / 20 0 0 0 CTB 46 73 47 81 / 10 20 0 0 HLN 51 82 53 87 / 20 0 0 0 BZN 45 82 49 89 / 30 0 0 0 WYS 35 73 37 79 / 20 0 0 0 DLN 42 79 46 85 / 10 0 0 0 HVR 50 80 52 86 / 40 20 20 0 LWT 46 75 49 80 / 40 10 20 0 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls