FXUS65 KTFX 091137 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 537 AM MDT Thu Jul 9 2026 Aviation Section Updated. .KEY MESSAGES... - Turning drier and much warmer through the weekend, with some record heat possible over the weekend. - Breezy conditions Saturday may result in some elevated fire conditions. - Not as hot next week, but still warm through next week. && .DISCUSSION... /Issued 335 AM MDT Thu Jul 9 2026/ While upper level flow will remain zonal/westerly over the next few days, expect generally drier and still warm conditions over the next 48 hours. The only exception to this may be a few isolated thunderstorms along the Continental Divide Friday as warmer air pushes into the area. Upper level ridging will build rapidly build late Friday and Saturday, which will cause temperatures to surge into the upper 90s to around 100F for most low elevation locations by Saturday afternoon, with many areas likely seeing 100F Sunday afternoon, though the exact temperature may depend on some incoming high clouds. Upper level flow will shift to more westerly on Monday, which will allow temperatures to lower a bit from the weekend highs, but most areas will still be quite warm with temperatures well into the 80s to low 90s. With this upper level flow pattern, expect generally dry conditions with just a few showers and thunderstorms to pop up in the afternoon. A passing upper level trough may bring some more widespread showers and storms on Wednesday, though timing of the trough passage will ultimately determine just how widespread and intense the storms will be. - Forecast Confidence & Scenarios: Heat this weekend: Models have been in very good agreement in regards to very warm to hot temperatures across North Central and Southwestern Montana this weekend. While the NBM has begun to forecast some record heat (with even some all time records in jeopardy across Southwestern Montana), there remains a slight bit of uncertainty with regards to just how hot it will get. Most models seem to be hinting at some thin, high cirrus clouds streaming in. While at first glance this may sound like a likely failure mode, and it might be, thin cirrus clouds have a documented ability to provide a net greenhouse effect by allowing incoming infrared light to pass through, but keep outgoing infrared heat trapped below them. So given this interaction, I see no reason to deviate from the NBM’s rather warm forecast. I heavily debated whether or not to issue an Extreme Heat Watch, but given the potential for all time record highs in some locations, even if temperatures come in slightly cooler than expected it will still be hot enough for at least a Heat Advisory. Ludwig && .AVIATION... 09/12Z TAF Period VFR conditions are expected over the next 24 hours, though warm temperatures may result in some density issues, particularly at KWYS, KEKS, and KBZN. Ludwig && .PRELIMINARY POINT TEMPS/POPS... GTF 88 56 94 59 / 10 0 0 10 CTB 82 55 86 57 / 10 0 0 10 HLN 88 56 91 60 / 10 0 10 10 BZN 87 54 91 57 / 10 0 10 10 WYS 83 45 86 47 / 20 10 0 10 DLN 86 52 88 54 / 10 0 10 10 HVR 88 56 92 59 / 10 0 0 10 LWT 83 53 89 55 / 10 0 10 20 && .TFX WATCHES/WARNINGS/ADVISORIES... Extreme Heat Watch from Sunday afternoon through Sunday evening for Canyon Ferry Area-Fergus County below 4500ft-Gallatin Valley- Madison River Valley-Missouri Headwaters-Northern Blaine County. && $$ http://www.weather.gov/greatfalls