Big Picture Weather Pattern:

A large trough of low pressure will take hold across the Pacific Northwest this weekend with several pulses of moisture tracking across the region along with colder air. Meanwhile, a weaker area of low pressure will move across Colorado on Friday, acting as a focal point for scattered thunderstorms. 

5-Day Precipitation Forecast:

Rainfall over the next 5 days will favor the Cascades and Northern Rockies. The Southern Rockies will also see scattered thunderstorms on Friday, followed by more isolated coverage and decreasing chances in the days to follow.

Colder air arriving means there will also be snow for the higher terrain with the Northwest and Northern Rockies storm system. Snow levels are expected to lower to pass levels in the Northern Rockies on Monday and Tuesday.

Pacific Northwest Outlook:

It will be a cool and wet weekend for areas along and west of the Cascade crest. The Central and Northern Cascades are favored for the heaviest precipitation totals, with 0.75 to 1.50 inches expected. Saturday will be the wettest day of the weekend, with lighter showers on Sunday. Areas east of the Cascades will be in the rain shadow through Sunday. 

We are forecasting 0.77 inches of rain in Longmire on Saturday, which is located on the western border of Mt. Rainier National Park with a high of only 45ºF. There will also be enough instability for isolated thunderstorms to develop across this region.

Moving higher up, a transition from rain to snow is expected at Paradise (elevation 5,440 feet) in Mt. Rainier National Park on Saturday with snow levels dipping to around 4,400 feet. We are forecasting 3-5 inches of snow at Paradise during the day on Saturday. 

West-Wide Forecast for Fri (Jun 14) to Sat (Jun 15):

On Friday, light showers will develop over the Pacific Northwest while the Southern Rockies (primarily New Mexico and Colorado) will see scattered thunderstorms with frequent lightning and localized downpours possible.

Strong to severe thunderstorms will also be possible along and east of the Front Range foothills, with large hail and strong straight-line winds posing the greatest risk.

To the north, areas of Southern Montana near the Wyoming border will also be favored for thunderstorms on Friday, and the potential exists for strong to severe thunderstorms in this region, too.

On Saturday, heavier and more widespread rain will move into the Pacific Northwest and isolated thunderstorms are also possible. For the Southern Rockies, thunderstorms will be more isolated in nature.

Forecast for Sun (Jun 16) to Mon (Jun 17):

Additional showers can be expected across the Cascades and Pacific Northwest, but the focus of heavy precipitation will shift into Idaho and Montana where significant rain and high-elevation snow is expected. The southern extent of moisture will make it into far Northern Nevada and Northern Wyoming, with dry conditions to the south.

Major mountain passes in the Northern Rockies can expect a transition to snow, including Logan Pass, Lost Trail Pass, Galena Pass, and Beartooth Pass.

Forecast for Tue (Jun 18) to Wed (Jun 19):

Lingering rain and snow showers across the Northern Rockies on Tuesday will give way to a drying trend on Wednesday. The Northwest will also begin to see a drying trend aside from some isolated showers and lingering chilly temperatures.

Moisture will likely return to the Southern Rockies during this period with thunderstorm chances increasing across New Mexico and Colorado.

Outlook for Thu (Jun 20) to Mon (Jun 24):

The mid-June cool and wet spell for the Northwest will come to an end late next week and a rebound to above-average warmth is expected throughout the West. Temperatures are expected to be well above average across California with excessive heat possible for the lower valleys.

The Southern Rockies will see a transition to a more active pattern as a substantial push of subtropical moisture arrives from the south, resulting in an uptick in thunderstorm activity and rainfall potential. 

Thanks so much for reading and have a great weekend! Next update on Monday (June 17).

Alan Smith 

NEW: Lightning Risk Map