Big Picture:

A more consistent monsoonal circulation is taking hold across the Southwest and Southern Rockies and will remain in place with minor fluctuations for the foreseeable future. High pressure is located well east of the Rockies over South Texas, while an area of low pressure over California is helping to draw in moisture to the Southwest.

Counterclockwise (cyclonic) winds rotating around this low will also bring moisture into the Sierra where more frequent thunderstorms can be expected compared to recent weeks.

This pattern will result in near-daily potential for lightning across the higher peaks from Colorado to California, while isolated flash flooding due to thunderstorm rainfall will also be possible in slot canyons and dry washes.

Temperatures will start out cooler than average for a large portion of the West on Friday.

However, areas west of the Continental Divide will see a warming trend from this weekend through early next week. 

A strong ridge of high pressure building along the West Coast will result in well-above-average temperatures over the PNW by Tuesday. The National Weather Service has already issued Excessive Heat Watches for portions of Western Oregon on Tuesday.

Cooler than average temperatures can be expected east of the Continental Divide from Wyoming to New Mexico this weekend and into early next week. 

Fire and Smoke Outlook:

The wildfire situation remains quiet by August standards in the Lower 48 and Western Canada, while winds associated with Hurricane Dora in the Pacific resulted in devastating wildfires in Hawaii this week.

On the mainland, recent cooler and wetter conditions have resulted in reduced fire activity and smoke overall. The most active fire currently is the Bedrock Fire in the Oregon Cascades between Eugene and Bend. This fire will send light smoke into portions of Eastern Oregon, Idaho, and Montana at times through the weekend.

Forecast for Friday:

Thunderstorm activity will favor the Sierra Nevada Range, Nevada, Utah, Arizona, Colorado, and New Mexico. Coverage will be scattered in nature with stronger storms capable of producing frequent lightning and heavy rain.

Forecast for Saturday:

Saturday's pattern looks very similar to Friday with scattered thunderstorms expected from the Sierra to Colorado & New Mexico. Further north, a cold front sliding down the east side of the Continental Divide will result in an uptick in moisture and shower/thunderstorms chances across the Canadian Rockies as well as the easternmost ranges of Montana and Wyoming.

Forecast for Sunday:

More of the same can be expected with scattered thunderstorms across the Sierra, Southwest, and Southern Rockies. The Front Range and Sangre de Christo Range may see an uptick in thunderstorm coverage from recent days.

Forecast for Monday to Tuesday:

A consistent thunderstorm pattern will remain in place across the Southwest, but moisture will gradually shift eastward compared to the weekend, resulting in a greater focus across Colorado and New Mexico. Also, the Sierra may see a break in the action on Tuesday.

Outlook for Wednesday (Aug 16) to Sunday (Aug 20):

An active monsoon pattern will remain in place during this period across the Southwest and Southern Rockies. Also, a new trough of low pressure setting up near the West Coast may help to transport some of this moisture back into the Sierra and the Northern Rockies. 

Despite the uptick in moisture, temperatures are expected to be warmer-than-average throughout the West with the highest confidence of above-average warmth existing across the Pacific Northwest. 

Thanks so much for reading! Next update on Monday (August 14).

Alan Smith