Forecast for Wednesday:

An active day is in store for the Interior West thanks to two low pressure troughs – one located over the  Southwest and one located over the Northern Rockies.

Moisture associated with the southern trough will result in widespread thunderstorm activity concentrated from the Central/Southern Sierra into the Great Basin, Utah, and parts of Western Colorado. Locally heavy rain will be possible under stronger thunderstorms, especially across Central and Northern Utah including the Wasatch Range.

Further north, showers can be expected across Wyoming and Montana with less lightning activity compared to recent days. Heavier and more widespread rain will fall across Eastern BC and Western Alberta, which should help with the fire situation. Snow will also fall across the higher elevations of the Canadian Rockies. 

Forecast for Thursday:

Moisture will remain stretched across the Southern Great Basin and Central Rockies with a slight southward and eastward shift. The most widespread thunderstorms and heaviest rainfall can be expected across Central/Southern Utah, Northern/Central Colorado, and Central Wyoming. 

Further west, scattered thunderstorms will favor the Southern Sierra Nevada Range with only isolated activity further north around Tahoe.

Across the Northern Rockies and Canada, an overall drying trend is expected with only a slight chance of showers.

Forecast for Friday:

A slight eastward trend in showers/thunderstorms will continue as the southern trough of low pressure slowly progresses eastward. Scattered thunderstorms will remain possible across the Southern Sierra as well as Southern Utah, with some of this activity extending into Northern Arizona.

Further east, more numerous thunderstorms can be expected statewide across Colorado with the potential for heavy rain. Scattered thunderstorms are expected across much of Wyoming as well with drier conditions further north.

A trough of low pressure will be deepening over the Gulf of Alaska with rain developing across Western and Northern BC, while showers could also develop across the Washington Cascades on Friday night.

Forecast for Saturday to Sunday:

The previous trough will continue to push eastward across Colorado and eventually out onto the plains, with lingering moisture resulting in scattered thunderstorms across Colorado on Saturday. A drying trend can be expected further west on Saturday from Utah to California.

Meanwhile, a trough originating in the Gulf of Alaska will continue to deepen southward with showers and thunderstorms developing across Western Canada, the Cascades, and the Northern Rockies as the weekend progresses. Colder air will also reach Canada during this period with snow possible across the higher elevations of BC and Alberta. 

Outlook for Monday (June 19) to Friday (June 23):

A powerful trough of low pressure with colder air will impact the Northwest and Northern Rockies during the first half of next week, with numerous showers and thunderstorms expected along with the potential for heavy rain in some areas. Accumulating snow is also a possibility across the higher elevations.

A drying trend is possible across most of the West toward the end of next week.

There is a high likelihood of below-average temperatures for all areas west of the Continental Divide next week, while temperatures will be near to above average east of the Continental Divide in Colorado and New Mexico. 

Thanks so much for reading! Next update on Friday (June 16).

Alan Smith