Big Picture Weather Pattern:

Monsoonal moisture rotating around high and low pressure areas in the Southwest will result in daily rounds of scattered thunderstorms along and west of the Continental Divide with heavy rain possible. 

A cold front will also slide from NNW to SSE through the Rockies from Wednesday to Thursday. Temperatures will cool down significantly east of the Divide and winds blowing from the east behind this front will transport abundant moisture into the Eastern Rockies from Montana to Colorado, resulting in showers and storms with heavy downpours.

5-Day Temperature Forecast:

Much cooler air will settle into place east of the Continental Divide with temperatures running below average for early August. Areas closer to the West Coast will remain warmer than average, but not excessively so compared to what we saw in July. 

Fire and Smoke Outlook:

The smoke forecast has worsened for the second half of the week, due to an uptick in new wildfires and current wildfires in recent days across the Northwest. This is largely a result of gusty winds and low relative humidity, while lightning from dry thunderstorms has likely played a role as well.

Wednesday – Smoky conditions are expected across much of the Interior Northwest and Northern Rockies. Strong westerly winds associated with a trough over the Northern Rockies has led to a plume of heavier smoke that will impact Southern Idaho and Central Wyoming, with the plume gradually working southward into Northern Utah by late Wednesday afternoon.

High-Res Smoke (Sky) Forecast for 5pm Wednesday:

Thursday – Smoke will continue to progress southward into Utah and Colorado in association with a southward-moving cold front, while Northern Montana will see a break from the smoke. Conditions will also remain smoky across the Pacific Northwest.

High-Res Smoke (Sky) Forecast for 5pm Thursday:

Friday – Smoky conditions from Northwest wildfires will continue to impact portions of the Interior West. Southern Idaho and Western Wyoming look to take the brunt of the smoke transport east of these fires, while Northern Utah and Northern Colorado look to be right on the edge. 

Air Quality Forecast for 3pm Friday:

Rain and Thunderstorm Forecast for Wed (Aug 7) to Thu (Aug 8):

Showers and thunderstorms will favor the eastern ranges of the Northern Rockies, as well as the Southwest – especially Colorado, Arizona, and Northern New Mexico.

Colorado:

On Wednesday, scattered thunderstorms will favor areas along and West of the Continental Divide throughout the state.

On Thursday, a significant uptick in coverage is expected along and east of the Continental Divide from the Front Range to the Sangres, including a threat of flash flooding – especially for southern areas.

The San Juans and central ranges will see more storms on Thursday as well, while Northwest Colorado (Flat Tops, Gores, Parks) will see more isolated activity on Thursday compared to Wednesday.

Utah:

On Wednesday, thunderstorm activity will be more isolated, primarily favoring eastern portions of the state from the Uintas to the Moab region. On Thursday, an uptick in coverage is expected across Southern Utah though coverage will still be widely scattered in nature.

More significant moisture in Utah will hold off until later in the week and over the weekend, but there is still a chance of localized flash flooding in slot canyons, dry washes, and small streams across Southern Utah on Wednesday and Thursday.

Arizona:

Scattered thunderstorms can be expected across Northern and Southern Arizona on both Wednesday and Thursday, with greater coverage on Thursday compared to Wednesday. Storms will be capable of producing locally heavy rain, with a risk of flash flooding in slot canyons, dry washes, small streams, and burn scars.

New Mexico:

Isolated to widely scattered thunderstorms can be expected across Northern and Western New Mexico on Wednesday, with more numerous storms developing across Northern New Mexico on Thursday. An increased risk of flash flooding is also expected on Thursday.

Northern Rockies:

On Wednesday, numerous showers and thunderstorms can be expected along and east of the Continental Divide from Glacier National Park to Central Wyoming, with heavy rain possible. Conditions will be much drier west of the Continental Divide.

On Thursday, a drying trend is expected in Montana with isolated activity favoring southern portions of the state, while the eastern side of the Divide in Wyoming (Bighorns, Absarokas, Winds) will see another active day.

Here is our forecast for Cloud Peak, which is the highest point in the Bighorn Range at just over 13,000 feet. The cooler air arriving in conjunction with abundant moisture will result in snow falling near the top of this peak on Thursday. Just a reminder that snow can fall at any time of the year in high-elevation alpine environments. 

Forecast for Fri (Aug 9) to Sat (Aug 10):

Monsoonal moisture will surge northward and a series of robust shortwaves will track across the Rockies, resulting in an active pattern with scattered to numerous thunderstorms throughout the Rockies. Utah and Colorado will be most favored for heavy rainfall, including an increased risk of flash flooding in Southern Utah.

The Cascades and Interior Northwest could also see some isolated showers and thunderstorms with more numerous storms north of the border in Canada. 

Forecast for Sun (Aug 11) to Mon (Aug 12):

An active pattern will continue with scattered to numerous thunderstorms throughout the Rockies, with Colorado and Utah favored for the heaviest rainfall once again. The Northern Cascades will also hang onto isolated shower/thunderstorm chances.

Outlook for Tue (Aug 13) to Sat (Aug 17):

The pattern will remain active heading into mid-August with monsoonal thunderstorms across the Four Corners region with locally heavy rain possible at times. The Northwest and Northern Rockies will also stay unsettled with frequent disturbances resulting in showers and thunderstorms.

A trough of low pressure setting up over the West Coast will also result in cooler temperatures (near to below average), while the Rockies will see above or near-average temperatures.