FXUS65 KTFX 230545 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 1145 PM MDT Tue Oct 22 2024 Updated AViation Discussion .SYNOPSIS... Today it will be cool, breezy, and sunny. Tomorrow it will warm up and then a shortwave will move through Southwestern Montana bringing light lower elevation rain and mountain snow. On Thursday it will be cool before it warms back up for the weekend. It will be dry Thursday afternoon through at least Sunday afternoon/evening. && .UPDATE... Only minor adjustments were made to the short-term forecast based on updated model guidance. Otherwise no major changes were made. There is still a less than 20% chance of fog development in some of the valleys of southwestern Montana including West Yellowstone. However, confidence is not particularly high at the moment so the mention of it was left out with this update. -thor && .AVIATION... 23/06Z TAF Period High level clouds/moisture will gradually increase from south to north across the Northern Rockies and MT later tonight through Wednesday morning with VFR conditions prevailing across N-central and SW MT terminals. Next weather system begins moving into the region Wednesday afternoon and evening for increasing mid level clouds with areas of precipitation and mountain obscuration developing across SW MT by Wednesday evening. Breezy W to SW surface winds persist along the east slopes of the Rockies tonight and become more widespread on Wednesday with surface winds across SW MT shifting to the NW Wednesday evening. Hoenisch Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PREV DISCUSSION... /ISSUED 609 PM MDT Tue Oct 22 2024/ This afternoon through Thursday... This afternoon there is upper- level zonal flow over the area. This will bring sunny skies, dry, and cool weather (slightly above seasonal averages) to the area. On Wednesday an upper-level ridge moves over North-central, Central, and Southwestern Montana. This will warm temperatures up to well- above seasonal averages with dry conditions during the day on Wednesday. Wednesday night into Thursday morning an upper-level shortwave trough will move through Southwestern Montana bringing lower-elevation rain and mountain snow to Southwestern Montana. On Thursday there will be mostly zonal flow over North-central, Central, and Southwestern Montana after the shortwave trough moves through Southwestern Montana Thursday morning. This will allow temperatures to cool back down to about seasonal averages on Thursday with dry conditions for North-central and Central Montana and Southwestern Montana after Thursday morning. Wednesday through Thursday there is a 35 - 60% chance for greater than a tenth of an inch of liquid precipitation across Southwestern Montana. Wednesday through Thursday there is a 60 - 90% chance of a quarter inch of liquid precipitation or greater in Southern Gallatin, Southeastern Madison, and extreme Eastern Beaverhead Counties. Wednesday through Thursday there is a 50 - 80% chance for an inch of snow or greater across the mountains of Southwestern Montana. Across the higher peaks of Southwestern Montana on Wednesday through Thursday there is a 60% chance for 2 inches of snow or greater. Friday through next Tuesday... On Friday an upper-level ridge begins to move over North-central, Central, and Southwestern Montana. This will begin to warm temperatures above seasonal averages and bring dry weather to the area. On Saturday the upper-level ridge remains over North-central, Central, and Southwestern Montana. This will warm temperatures to well-above seasonal averages with dry conditions. On Sunday cluster analysis shows an upper-level ridge over North-central, Central, and Southwestern Montana. This will maintain the warm and dry weather for the area. On Monday three of the four clusters (84% of ensemble members) have an upper-level trough over North-central, Central, and Southwestern Montana. This scenario would bring cooler temperatures and precipitation to the area. The other cluster (16% of ensemble members) has an upper-level ridge over North-central, Central, and Southwestern Montana. This scenario would maintain warm and dry weather for the area on Monday. On next Tuesday cluster analysis shows an upper-level trough over North-central, Central, and Southwestern Montana. This would bring cooler temperatures and precipitation chances to the area. -IG && .PRELIMINARY POINT TEMPS/POPS... GTF 31 60 32 54 / 0 10 10 0 CTB 26 54 28 50 / 0 0 0 0 HLN 30 59 32 55 / 0 20 50 0 BZN 27 59 27 54 / 0 10 90 10 WYS 21 53 22 42 / 0 10 90 30 DLN 29 58 26 51 / 0 20 80 0 HVR 28 58 28 55 / 0 0 0 0 LWT 29 61 29 52 / 0 0 40 0 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls