Area Forecast Discussion
Issued by NWS Great Falls, MT
Issued by NWS Great Falls, MT
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292 FXUS65 KTFX 161801 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 1200 PM MDT Sun Jun 16 2024 .SYNOPSIS... Gusty west winds along the Rocky Mountain Front and Plains continue through the morning. Widespread precipitation bringing mountain snow and lower elevation rain arrives Sunday night and lasts through Tuesday evening. Below average temperatures forecasted for Monday and Tuesday. Temperatures gradually warm up through the rest of the week. Daily low chances for precipitation remains through the week. && .UPDATE... With this update, I`ve expired the High Wind Warning, with a note that strong gusty winds continue and decrease throughout the day. Additionally, I`ve touched the wind speed/gust forecast, to bring the forecast in line with observed conditions. Aside from these adjustments, no noteworthy changes are made. - Fogleman && .AVIATION... 16/18Z TAF Period VFR conditions are expected to prevail through midnight or so across North Central and Southwestern Montana, with some gusty winds from KHLN north. Expect clouds to gradually thicken today, with MVFR cigs beginning to become possible around/after midnight with rain and mountain snow developing. After midnight, expect periods of MVFR to IFR conditions as low cigs and rainfall spread across North Central and Southwestern Montana, along with mountain obscuration. Ludwig Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PREV DISCUSSION... /ISSUED 456 AM MDT Sun Jun 16 2024 Today through monday...Water vapor satellite shows mountain wave activity producing strong winds along the Rocky Mountain Front. High winds across the Rocky Mountain Front and and plains continue through the morning hours as High Wind Warning for the Rocky Mountain Front is set to expire by 9am. Be prepared for strong crosswinds if traveling this morning. A surface front swinging down from Canada will create some light showers along the northern Hi-Line/Rocky Mountain Front region this morning ahead of the main system moving in later in the day. Energy from this upper level trough will move into the region during the evening hours, bringing in lower elevation rain and snow for elevations generally above 6,000ft. Precipitation will become more widespread and heavier Monday morning with the upper level low moving passing through the region. There may be a few embedded thunderstorms with precipitation on Monday/Tuesday afternoon due to a little amount of instability present. Precipitation lingers into Tuesday along another wave of passing through the region. Snow probabilities in the mountains are between 30-50% for exceeding 8" of snow. Considering the bulk of the snow being above pass level and probabilities for accumulations to reach winter warning criteria (9 inches) remain on the lower side, I have opted to transition the Winter Storm Watches for mountain zones into Winter Weather Advisories. Another change I`ve made to the winter highlights is to move up the timing to 6pm Sunday to 6pm Tuesday to account for the earlier start and end times for precipitation. Greatest QPF amounts look to set up across Central MT, where they hav.DISCUSSION... e around a 50% of exceeding 1". Most other lower elevations across the CWA have at least a 50% of exceeding 0.25". In terms of possible higher end QPF amounts, the 75th NBM percentile ranges between 1.25-1.5" across Central MT and 0.35-0.75" across most other lower elevations. With the upper level low bringing down colder air, cold overnight temperatures are forecasted for Monday and Tuesday morning. Tuesday morning wind chills in the mountains can drop down to the teens and 20s. Those in the backcountry should prepare for cold/raw conditions. Wednesday and looking beyond...The main upper level low will move off to the east, and a zonal/southwest flow aloft pattern will settle in behind for the remainder of the week. There looks to be enough moisture around and small disturbances that passes through to keep low chances of precipitation daily. With the southwest flow aloft bringing in warmer air, temperatures will gradually warm up through the weekend. By Saturday, lower elevations have a 60-80% of high temperatures reaching 80 degrees or higher. -Wilson && .PRELIMINARY POINT TEMPS/POPS... GTF 66 42 50 40 / 0 40 100 80 CTB 59 36 54 37 / 30 10 70 50 HLN 68 43 53 41 / 0 50 100 80 BZN 67 41 55 36 / 0 30 100 100 WYS 61 38 51 30 / 0 10 70 70 DLN 65 38 51 34 / 0 40 100 60 HVR 63 42 57 42 / 30 10 80 60 LWT 63 38 50 35 / 0 30 100 100 && .TFX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 6 PM this evening to 6 PM MDT Tuesday for Big Belt, Bridger and Castle Mountains-East Glacier Park Region-Elkhorn and Boulder Mountains-Gallatin and Madison County Mountains and Centennial Mountains-Little Belt and Highwood Mountains-Northwest Beaverhead County-Southern Rocky Mountain Front. && $$ http://www.weather.gov/greatfalls