Area Forecast Discussion
Issued by NWS Great Falls, MT
Issued by NWS Great Falls, MT
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218 FXUS65 KTFX 301135 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 535 AM MDT Thu May 30 2024 UPDATED AVIATION SECTION .SYNOPSIS... Today fog could form in the West Yellowstone area and along the Idaho border in Southern Southwestern Montana. Today an upper-level disturbance will bring rain showers to the eastern portion of the Hi-Line. It will be windy along the Rocky Mountain Front today. Unsettled weather will continue through at least Tuesday with a warm up possible for the middle of next week. && .DISCUSSION... Today through Friday... Today there is an upper-level trough in place over North-central, Central, and Southwestern Montana. This will keep temperatures cool. This morning in the West Yellowstone area and isolated other locations of Southern Southwestern Montana near the Idaho border fog could form due to the precipitation that fell today and light winds. Late this morning through this afternoon an upper-level disturbance will move along the Hi-Line and bring rain showers to the central and eastern portion and areas just south of the Hi-Line. Today there is a 20 - 40% chance for locations along the central and eastern portion of the Hi-Line south to Fort Benton receiving a tenth of an inch of rain (total liquid amount for mountain locations) or more. Today for the mountains of North-Central, Central, and Southwestern Montana there is 20 - 60% chance for receiving a tenth of an inch of snow or more. Today due to a strong surface pressure gradient along the Rocky Mountain Front there is a 60 - 80% chance for wind gusts exceeding 55 mph. Today along the plains adjacent to the Rocky Mountain Front and across isolated locations of Central and North- central Montana there is a 50 - 80% chance for wind gusts exceeding 47 mph. On Friday the upper-level trough slowly begins to move to the east away from North-central, Central, and Southwestern Montana. This will allow temperatures to warm up to near seasonal averages on Friday. Friday morning across the lower- elevations of Southwestern Montana there is the potential for frost to form, but if it forms it will melt quickly. On Friday it will be dry across the area. Saturday through Monday... On Saturday a weak upper-level ridge moves over North-central, Central, and Southwestern Montana. This will warm up temperatures and keep most of North-central and Central Montana dry with precipitation chances (10-20%) south of the Montana Highway 200 Corridor Saturday afternoon and evening. On Sunday across North-central, Central, and Southwestern Montana there will be mostly zonal flow with a few upper-level disturbances before an upper-level ridge begins to move into the area Sunday evening. This will bring a 10 - 20% chance for a tenth of an inch of rain to Southwestern Montana early Sunday morning through Sunday evening. On Monday the upper-level ridge remains in place over North-central, Central, and Southwestern Montana. On Monday due to strong upper- level flow there will be strong wind gusts along the Rocky Mountain Front and adjacent plains and in isolated locations of Southwestern Montana. There is a 60% chance for locations along the plains adjacent to the Rocky Mountain Front and in isolated locations of Southwestern Montana having wind gusts exceeding 47 mph. On Monday along the Rocky Mountain Front there is a 50 - 80% chance for wind gusts exceeding 55 mph. This will need to continue to be monitored. Monday afternoon and evening there is 20% chance for a tenth of inch of rain for the lower-elevations of North-central, Central, and Southwestern Montana. Tuesday through next Thursday... On Tuesday clusters indicate that a weak upper-level trough will move over North-central, Central, and Southwestern Montana. This indicates that unsettled weather will continue for Tuesday across the area. On Wednesday three clusters (76% of ensemble members) indicate that an upper-level ridge moves back over North-central, Central, and Southwestern Montana. The other cluster (24% of ensemble members) keeps the upper-level trough over North-central, Central, and Southwestern Montana. This indicates that unsettled weather could continue for Wednesday or it could be warm and dry across the area. Next Thursday clusters have an upper-level ridge over North-central, Central, and Southwestern Montana. Two of the clusters (72% of ensemble members) have a stronger ridge. This indicates that temperatures could warm back up to above seasonal averages. This will need to continue to be monitored. -IG && .AVIATION... 30/12Z TAF Period VFR conditions are expected to continue through at least 31/06Z across North Central (KCTB, KHVR), Central (KLWT, KGTF, KHLN), and Southwest (KBZN, KEKS, KWYS) Montana, unless otherwise noted. Areas of mid- and high-level cloudiness will move over the area in a moderate northwest flow aloft through at least 03Z. Patchy fog in some southwest valleys (including KBZN KWYS) could reduce conditions to MVFR between 12Z and 16Z, but the cloud cover there is making it less likely for this significant reduction to occur. The winds aloft will cause mountain wave turbulence through the period, as well as some low level wind shear (mainly over North Central and Central Montana) until the increasing westerly surface winds mix down to the surface again after 14Z. A disturbance in the flow aloft will bring a chance of showers to portions of North Central Montana (mainly in the KCTB and KHVR areas between 18Z and 00Z. Winds and clouds should generally decrease after 01Z. -Coulston Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PRELIMINARY POINT TEMPS/POPS... GTF 62 38 67 41 / 10 0 0 0 CTB 60 38 64 39 / 30 0 0 0 HLN 63 39 71 44 / 10 0 0 0 BZN 60 33 68 38 / 10 0 0 0 WYS 53 29 62 32 / 10 0 0 0 DLN 58 33 68 38 / 0 0 0 0 HVR 62 41 67 41 / 40 10 10 0 LWT 57 35 62 39 / 10 0 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls