textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Strong westerly winds are expected today with relatively dry cold front passage.

- Rain and snow showers return next weekend, especially in the mountains. Possible thunderstorms on Saturday.

Wind advisories are in effect across western Montana today with gusts over 30 mph anticipated. A few isolated wind gusts over 50 mph are possible. The highest probabilities from the REFS ensemble for gusts exceeding 50 mph include Ashley Lake to Kila, Blacktail Mountain, MacDonald Pass and over the Divide. There is a 60% chance for greater than 50 mph between Florence and Corvallis, generally along and west of US-93.

Temperatures will moderate into the 60s and 70s by Friday and Saturday.

The next trough will make landfall over the west coast by Saturday and Sunday. There is considerable spread in the model solutions on how this weather system will evolve.

On Saturday, we'll be under southwest flow which is a good pattern for showers and thunderstorms. Do we have the fuel for storms? The latest ensembles depict a 40% probability for instability (CAPE) values exceeding 400 J/KG from central Idaho into west-central Montana. The U. of WA GFS-based WRF is depicting multi-cellular thunderstorms initiating off the terrain in the areas mentioned. Lightning, gusty winds and small hail would be possible.

In terms of possible mountain snowfall, in the low end, there could be a skiff of snow that falls, but looking at the high end, there could be measurable snowfall by Sunday and/or Monday. There are some solutions that spin up a low over our region that interacts with cooler air drawing south out of Canada.

AVIATION

Expect a windy day today with the strongest wind gusts occurring between 07/1700Z and 08/0000Z, generally during the afternoon hours. Widespread gusts between 30-35 kts are expected. Winds will diminish somewhat by tonight. Expect VFR flying conditions on Wednesday with westerly winds generally staying under 20 knots.

MSO WATCHES/WARNINGS/ADVISORIES

MT...Wind Advisory from 9 AM this morning to 9 PM MDT this evening for Bitterroot/Sapphire Mountains...Butte/Blackfoot Region...Flathead/Mission Valleys...Kootenai/Cabinet Region...Lower Clark Fork Region...Missoula/Bitterroot Valleys...Potomac/Seeley Lake Region...West Glacier Region.

ID...None.