Area Forecast Discussion
Issued by NWS Missoula, MT
Issued by NWS Missoula, MT
357 FXUS65 KMSO 290806 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 206 AM MDT Mon Apr 29 2024 .DISCUSSION...An upper trough along the West Coast will come onshore this morning and wobble through the Northern Rockies into Wednesday ushering in cooler and unsettled conditions. A cold front will concentrate precipitation this morning across north-central Idaho/west-central Montana with 2-4 inches of snow above 5000 feet in locales such as Dixie, Lolo Pass, and Lost Trail Pass eastward to Georgetown Lake. Watch for transient slush on pass- level roadways and slippery conditions on backcountry roads. Considerable instability showers (maybe even a few rumbles of thunder) are anticipated later today as temperatures cool aloft, with additional showers on Tuesday and Wednesday. Snow levels will range from 2500-3500 feet by this evening lasting into Wednesday but valley impacts should be limited to a dusting on non-paved surfaces. A secondary disturbance may focus precipitation in Glacier Park and along the Divide on Wednesday with a 45% probability of over 4 inches of snow at Marias Pass. There is still uncertainty with the track of the disturbance as the 25th to 75th percentiles range from 1 to 7 inches respectively at Marias Pass. Once again, be cautious of intermittent slippery conditions on pass-level roadways in the overnight and morning periods. Daytime wind gusts of 20-30 mph will also be prevalent in valleys, tapering off during overnight periods today through Wednesday. It`s noteworthy that morning temperatures will be below normal throughout the middle and end of this week. The lower valleys of western Montana and higher valleys of north-central Idaho are projected to experience temperatures in the upper 20s to lower 30s. Gardeners with sensitive annuals outdoors should take necessary precautions. Models suggest another disturbance dropping down from British Columbia late Thursday into Friday, bringing more showers. Ensemble clusters support an active weather pattern with intermittent showers expected this weekend (May 4th-5th) through the first full week of May. && .AVIATION...An upper trough situated along the West Coast will come onshore this morning and propel a cold front through the Northern Rockies today. This cold front will concentrate precipitation this morning across north-central Idaho and west-central Montana, with snow levels near 4000 feet (closer to 6000 feet in southwest Montana). Considerable instability showers are anticipated later today continuing into Tuesday as temperatures cool aloft. Snow levels drop to 2500 feet this evening but valley impacts should be limited to a dusting on non paved surfaces. As precipitation occurs, expect reductions in ceiling and visibility, along with mountain obscurations, although these effects will likely be brief during afternoon and evening showers. Additionally, wind gusts of 20-25 knots will be common at terminal sites, gradually diminishing during overnight periods. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...Winter Weather Advisory until 6 PM MDT this evening for Bitterroot/Sapphire Mountains. Winter Weather Advisory from 6 AM this morning to 9 PM MDT this evening for Butte/Blackfoot Region. ID...Winter Weather Advisory until 6 PM MDT /5 PM PDT/ this evening for Eastern Lemhi County...Northern Clearwater Mountains... Southern Clearwater Mountains...Western Lemhi County. && $$