FXUS65 KTFX 181122 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 522 AM MDT Sat Jul 18 2026 Aviation Section Updated. .KEY MESSAGES... - Another round of scattered showers and thunderstorms will move in a southwest to northeast fashion this afternoon and tonight. - Thunderstorm hazards will include strong, gusty winds, hail, and heavy downpours capable of producing isolated instances of localized flooding. - Sunday will be breezy and dry with continued very warm to hot temperatures. - After a brief cooldown Monday, summer heat and daily rounds of storms return heading towards the middle of next week. && .DISCUSSION... /Issued 402 AM MDT Sat Jul 18 2026/ Lingering shower and thunderstorm activity from last night has mostly diminished and ended while some patchy areas of low stratus and fog develop over portions of central and southwest MT this morning. This should clear out by mid- morning with the focus turning to another shortwave passing through an unstable southwesterly flow aloft and bringing another round of scattered showers thunderstorms this afternoon and evening. Similar to yesterday, this activity will initialize over west and southwestern MT early in the afternoon before moving northeastward over the plains and valleys later in the afternoon and evening. Model guidance has ramped up today's ML CAPE values to around 800 to 1,500 J/kg, resulting in more widespread convective activity than what was anticipated 24 hours ago. Drier surface conditions suggest that instances of localized strong wind gusts over 60 mph will be more pronounced while shear above 25 kts will be marginally supportive of hail events. These storms will also be capable of producing isolated flooding of sensitive burn scars and urban areas, although PWATS look to drop off some compered to the last few days. Given slightly lower moisture levels and more progressive storm motion, I decided to hold off on flash flood products for now. Today's showers and storms should wind down by late this evening with increased westerly flow aloft bringing drier, breezy, and continued hot conditions on Sunday. Deep layer mixing and H700 flow approaching 30 to 35 kts will keep the windiest conditions along the Rocky Mountain Front and the plains. Any shower or thunderstorm activity will be isolated and mostly confined to the higher terrain of southwest MT. A Canadian surface front will bring a northerly wind shift and a brief cooldown on Monday before ridging aloft strengthens and brings a return to hot conditions heading towards the middle of next week. Passing shortwaves interacting with monsoon moisture will also increase daily shower and thunderstorm activity. - RCG && .AVIATION... 18/12Z TAF Period Patchy dense fog and low stratus has developed over some of the central and southwest valleys this morning. There will be intermittent MVFR/IFR/LIFR conditions at KBZN, KHLN, and KWYS through around 18/15Z. Another shortwave moves in from the southwest and brings additional scattered showers and storms moving in a southwest to northeast fashion, mostly between 18/20 and 19/06Z. Strong gusty winds will be the primary impact, but some storms will have hail and downpours as well. - RCG && .PRELIMINARY POINT TEMPS/POPS... GTF 95 61 95 59 / 30 30 0 0 CTB 91 57 87 55 / 20 20 0 0 HLN 93 61 94 59 / 40 50 10 0 BZN 92 57 93 56 / 30 30 10 10 WYS 87 48 86 48 / 20 20 0 0 DLN 89 55 90 55 / 30 30 0 0 HVR 97 63 95 58 / 30 30 0 0 LWT 89 57 90 54 / 30 40 20 10 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls