Big Picture Weather Pattern:

We have a few things going on this weekend. A trough of low pressure will move into the Western U.S., weakening as it encounters the dominant ridge of high pressure that has been responsible for this week's heat. However, the atmosphere will be unstable across the Intermountain West and this weakening trough will aid in triggering afternoon thunderstorms.

Also, a backdoor cold front will slide into Eastern Colorado and New Mexico from the northeast on Saturday. Winds blowing from the east will transport moisture from the Gulf of Mexico toward the Eastern Rockies, resulting in more numerous thunderstorms and heavy downpours in the Saturday to Monday timeframe. 

5-Day Precipitation Forecast:

Showers and thunderstorms will produce light to moderate rainfall over the next 5 days across the Great Basin and Central/Northern Rockies, while the eastern ranges including the Colorado Front Range and Sangre de Christo Range will be favored for higher totals. 

Colorado and Northern New Mexico:

Friday will be another hot day with isolated thunderstorms, while Saturday through Monday will feature numerous thunderstorms. Most of the action will happen during the afternoon and evening hours, though some overnight activity couldn't be ruled out.

Sunday looks like the wettest day across the Front Range and Northern Sangre de Christo Range, while Monday looks wettest across Southern Colorado and Northern New Mexico.

Areas west of the Divide will also see daily rounds of showers and thunderstorms from Friday to Monday, aided by an approaching trough from the west.

Below are forecasts for the summits of Humboldt Peak, CO (left image) and Wheeler Peak, NM (right image). High and low temperatures are displayed for the next 5 days on these screens (you can swipe left to view out to 10 days), while the graph display shows hourly lightning chances for Saturday.

Inclement weather will not just be confined to the higher peaks either. The Front Range foothills, including Buffalo Creek (image below) will see numerous thunderstorms with frequent lightning and locally heavy rain possible. 

We are projecting a total of 1.08 inches of rainfall at Buffalo Creek from Friday through Monday. Keep in mind that with thunderstorm activity, rainfall totals can be highly variable over short distances on any given day. 

West-Wide Forecast for Fri (Jun 7) to Sat (Jun 8):

On both days, we will see isolated afternoon thunderstorms west of the Continental Divide from the Sierra and Oregon Cascades to the Rockies with spotty rainfall. On the east side of the Divide, more numerous thunderstorms will develop in the Colorado Front Range and Southern Wyoming on Saturday afternoon with frequent lightning, hail, and locally heavy rain possible. 

Forecast for Sun (Jun 9) to Mon (Jun 10):

Widespread showers and thunderstorms with heavy rainfall can be expected across Southern Colorado and Northern New Mexico, especially over the Sangre de Christo Range. Scattered thunderstorms can be expected further north across the Front Range on both days, as well as areas west of the Divide.

A trough moving across the Northwest and Northern Rockies will help to trigger thunderstorms with Idaho, Montana, and Wyoming all looking favored. Frequent lightning and locally heavy downpours are possible.

The Oregon Cascades and Northern California will also see thunderstorms at a minimum, and the Washington Cascades could potentially see some storms as well.

Forecast for Tue (Jun 11) to Wed (Jun 12):

We will see a drying trend across the West aside from some stray afternoon thunderstorms over elevated terrain. The heat will also return to areas that will have had a reprieve during prior days.

North of the border, an approaching storm system will result in showers and thunderstorms across BC, while some light showers could also sneak into Western Washington.

Outlook for Thu (Jun 13) to Mon (Jun 17):

A ridge of high pressure will remain the dominant pattern over the Southwest, resulting in continued hot and dry conditions. The east side of the Divide in Colorado and New Mexico will also warm up significantly with well-above-average temperatures, though afternoon thunderstorms will remain possible over the higher terrain.

To the north, low pressure troughing is expected to return to the Pacific Northwest, resulting in a return to below-average temperatures. Shower chances will also be on the increase across this region, with a good chance of showers and thunderstorms spreading into the Northern Rockies as well. 

Thanks so much for reading and have a great weekend! Next update on Monday (June 10).

Alan Smith