Big Picture Weather Pattern:

A trough of low pressure will work its way across the Northern Rockies on Wednesday and Thursday. Another trough currently located over Alaska will drop south and move across the Northwest and portions of the Rockies from Friday through Sunday, though there is some model disagreement with the storm track once it reaches the Rockies.

Further south, dry and breezy conditions will prevail across Arizona and New Mexico, resulting in elevated fire danger.

7-Day Precipitation Forecast (May 22-29):

The Northwest and Northern Rockies will see the wettest conditions over the next week, with greater uncertainty for the Central Rockies due to poor model agreement on the storm track this weekend.

7-Day Snow Forecast (May 22-29):

High-elevation snow remains in the forecast with a chilly airmass (for late May) accompanying this stormy pattern. The heaviest snow totals are expected in the Northern Rockies, especially in Southwest Montana and over the Bitterroot Range along the Idaho/Montana border

Forecast for Wed (May 22) to Thu (May 24):

Showers will linger across the Cascades and Pacific Northwest on Wednesday as the heavier precipitation moves further east into the Northern Rockies. Widespread rain and snow can be expected across Idaho, Montana, Northern Wyoming, and the BC Interior and Canadian Rockies.

Colder air will arrive on Wednesday night and Thursday, with snow levels dipping to 5,000-6,000 feet in many areas.

To the south, isolated showers are possible in the Sierra, Northern Utah, and Colorado Rockies but overall these areas will be in a drier pattern.

Let's take a closer look at the Northern Rockies where the heaviest precipitation is expected. Many areas in Montana will see 1-2 inches of precipitation (rain and liquid-equivalent snow) with 0.5-1.3 inches for the higher terrain of Idaho and Northern Wyoming.

Many of the higher mountain ranges in this region will pick up 4-12 inches of new snow through Thursday night.

In the next image, we show two of our OpenSnow point forecasts in Southwest Montana.

The left image is an hourly precipitation forecast for Bozeman (elevation 4,826 feet) on Thursday. We are forecasting 0.71 inches of rain in town on Thursday (and a 2-day total of 0.88 inches) with a high temperature of 46ºF. You can view these hourly forecast graphs for any location by selecting the Weather tab at the top of the forecast page.

The right image is a daily forecast for Beartooth Pass (elevation 10,955 feet), which is accessed by tapping on the Snow Summary tab which shows 12-hour snowfall forecasts for each day and night out to 10 days. We are forecasting 7-15 inches of new snow from Wednesday morning through Thursday night, with a high temperature of only 20ºF on Thursday afternoon.

Forecast for Fri (May 24) to Sat (May 25):

The next storm will move into the Pacific Northwest on Friday and Friday night, and into the Rockies on Saturday with more rain and snow expected. Temperatures do not look quite as cold in this pattern and snow levels will be a little higher, but higher elevation terrain can still expect some snow.

There are some question marks on what happens across the Rockies as models are in poor agreement on the storm track.

The Northern Rockies have the best chance of seeing widespread precipitation, but we need to keep an eye on the Central Rockies (Utah and Colorado) as some models are hinting at heavier precipitation in these areas compared to what the model below is showing. The Sierra Nevada Range could see some lighter showers as well.

Forecast for Sat (May 26) to Sun (May 27):

On Sunday, lingering showers will be possible near and east of the Continental Divide in the Rockies, but we will see a warming and drying trend through Memorial Day on Monday.

Another storm will move into the Pacific Northwest later Sunday and into Monday. The heaviest rainfall is currently expected over British Columbia, but the Cascades and Olympics in Washington and Oregon could see some light to moderate rain as well with northern areas favored for the heaviest totals. 

Outlook for Tue (May 28) to Sat (Jun 1):

Most of the West will see a warmer and drier pattern next week as high pressure builds over the region, leading to above-average temperatures. North of the border, cooler temperatures will prevail across British Columbia.

Weaker disturbances could lead to occasional showers across the Olympics and Northern Cascades, but it won't be as wet compared to this week. Also, we could see enough moisture reach the eastern side of the Continental Divide in the Rockies for occasional thunderstorm activity. 

Thanks so much for reading! Next update on Friday (May 24).

Alan Smith