Forecast for Friday:

A trough of low pressure will move from the Great Basin into the Northern Rockies on Friday. Significant moisture, instability, and wind shear (change in wind speed/direction with height) will be present across the Northern Rockies as this trough approaches, resulting in the potential for strong to severe thunderstorms as well as heavy rain.

The threat of strong to severe thunderstorms will be greatest across Wyoming, with severe weather threats including large hail and damaging winds. Most of Wyoming will have a chance of seeing severe weather, as will Southern Montana and Eastern Idaho. The highest threat for severe weather will exist across the eastern half of Wyoming where a few tornadoes will also be possible.

Locally heavy rain will also be possible with thunderstorms throughout the Northern Rockies. However, the most widespread threat of heavy rain can be expected across Southern Montana from the Madison/Gallatin to the Beartooths and eastward, where flash flooding will also be a concern.

Further west, scattered showers and thunderstorms can also be expected across the Cascades, Western Canada, and Northern California, with more isolated activity around Tahoe and eastward into Northern Utah.

The Colorado Front Range will see a welcome reprieve after a couple of hectic days of severe weather with only some isolated activity expected, while a few severe storms still couldn't be ruled out on the plains east of Denver metro.

Forecast for Saturday:

Rain will linger across portions of Northern Wyoming and Southern Montana on Saturday with afternoon showers and thunderstorms possible across Idaho, Western Wyoming, and Southwest Montana. 

Meanwhile, another trough of low pressure will approach the West Coast with isolated thunderstorms developing across Oregon and Northern California including Tahoe. More numerous showers and thunderstorms can be expected across BC as well as the Northern Washington Cascades.

Dry and sunny conditions will prevail across Colorado and Utah and points southward, except for perhaps a stray thunderstorm over the Uinta Mountains. 

Forecast for Sunday:

A trough of low pressure will hang just off the California Coast on Sunday with isolated to scattered thunderstorms across the Sierra and Great Basin, as well as the Northern Rockies including Idaho, Montana, and Wyoming. Showers and thunderstorms can also be expected across BC and Alberta. 

Forecast for Monday to Tuesday:

The West Coast trough will continue to be the main influence next week with showers and thunderstorms favoring the Sierra, Great Basin, and Northern Rockies. It's also possible activity could extend into the Pacific Northwest, though confidence is low at this time. A dry pattern will prevail further south across Colorado and the Southwest. 

Outlook for Wednesday (June 28) to Sunday (July 2):

The second half of next week will favor a similar pattern with shower and thunderstorm chances favoring the Northern Rockies, while the Sierra should also see some activity. It's also possible we could see storm chances increase across the Northern Colorado Front Range.

A general warming trend is expected across the West next week with many areas starting to feel like summer. Above-average warmth is expected across the West Coast and the Southwest with near-average temperatures favored across the Central Rockies. 

Thanks so much for reading! Next update on Monday (June 26).

Alan Smith