FXUS65 KTFX 302338 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 538 PM MDT Wed Apr 30 2025 Aviation Section Updated. .KEY MESSAGES... - Scattered showers will slowly taper off this evening. - Warmer temperatures return with highs on Friday and Saturday rising into the 70s and 80s. - Unsettled weather returns this weekend into early next week with daily chances for showers and thunderstorms. && .DISCUSSION... /Issued 255 PM MDT Wed Apr 30 2025/ - Meteorological Overview: Today through tonight...Moist, northwest flow in wake of an overnight shortwave will help to support showers across Southwest through North Central Montana through the late afternoon to evening hours, with highest areal coverage of showers being focused over the mountains in in northerly upslope areas. Additional precipitation amounts beneath any given shower will generally be light and less than 0.05"; however, a few of the stronger showers could produce localized amounts of 0.10" to nearly 0.25" Thursday through Friday...A strong upper level ridge will build in over the Northern Rockies through the end of the work week. This upper level ridge will bring well above normal temperatures, with high temperatures by Friday of 10 to nearly 25 degrees above normal, and dry conditions to all locations. Saturday through next Tuesday..Longwave troughing off of the Eastern Pacific will begin to dig towards the Great Basin and Desert Southwest through the weekend, with the upper level ridge axis sliding east of the Northern Rockies through the day on Saturday as southerly flow develops over Southwest through North Central Montana. Strong warm air advection within this southerly flow ahead of this longwave trough on Saturday will once again help to push high temperatures well above normal, with lower elevations peaking in the mid-70s to mid-80s. Increasing moisture within the southerly flow aloft will also bring a return chance for showers and thunderstorms on Saturday to most locations. Temperatures "cool" slightly through the second half of the weekend and first half of the upcoming work week as the longwave trough moves across the Western CONUS, with daily chances for precipitation. Precipitation chances, at this time, from Sunday through Tuesday will be highest along and south of the Montana Hwy 200 corridor - Moldan - Forecast Confidence & Scenarios: The latest model guidance remains confident in well above normal temperatures across the region on Saturday where highs across the lower elevations will range from the upper 70s to mid 80s. The warmest temperatures are expected along the northern plains where there is a 40 to 60% chance of highs exceeding 85 degrees on Saturday. After a relatively dry Friday, unsettled weather is expected to return Saturday through the middle of next week. As of now, the greatest concern for afternoon thunderstorms is on Saturday. Sufficient daytime heating in combination with relatively moist air and forcing from the trough are expected to be enough to allow for isolated to scattered thunderstorms across the region. Although the finer details remain uncertain at this time, the main concerns look to be gusty winds and generally small hail (less than half an inch). -thor && .AVIATION... 01/00Z TAF Period Scattered showers over Central and North-central Montana mostly decrease by 01/04Z, but another weak shortwave will maintain mostly mid-level clouds over the northern two thirds of the forecast area and at least some isolated shower activity along the Hi-Line heading into the overnight hours. Lingering surface moisture and light winds may also encourage some patchy fog development between 01/09 and 01/16Z in the KWYS area. Ridging aloft begins to build in on Thursday, but a northwesterly flow may bring scattered to broken clouds and northwesterly surface winds gusting over 25 kts at times, mostly for areas east of interstate 15. - RCG Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PRELIMINARY POINT TEMPS/POPS... GTF 38 65 40 78 / 10 0 0 0 CTB 36 65 36 76 / 10 0 0 0 HLN 38 67 41 78 / 10 0 0 0 BZN 33 62 33 73 / 10 0 0 0 WYS 23 58 23 65 / 10 0 0 0 DLN 33 62 36 73 / 10 0 0 0 HVR 36 66 36 79 / 30 0 0 0 LWT 34 60 35 72 / 30 10 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls