Big Picture Weather Pattern:

The two main weather players for the middle of this week are a trough of low pressure moving across Northern Montana (chilly temperatures and rain/snow) and monsoonal moisture over New Mexico, and to a lesser extent, Eastern Arizona and Southern Colorado.

Drier air is moving into Utah and most of Colorado and Wyoming, and the Pacific Northwest is also drying out after an extended stretch of cooler and wetter-than-average conditions. 

5-Day Temperature Forecast:

A warming trend will take hold from west to east, with the Pacific Northwest trending well above average. The Rockies will start out cooler than average in this pattern but warm up to above-average levels by the weekend.

Forecast for Fri (Aug 30) to Sat (Aug 31):

The Northern Rockies system will favor Northern Montana and the Canadian Rockies. To the south, New Mexico will be favored for thunderstorms, with isolated to scattered activity in Eastern Arizona and Southern Colorado. 

Northern Rockies:

Significant rainfall amounts will occur over Northern Montana, especially in and near Glacier National Park. Rain will fall from Wednesday morning into Thursday morning before drying out during the day on Thursday. Southern Montana will not see much moisture from this system and Wyoming and Southern Idaho will stay dry. 

The higher terrain in and around Glacier will also pick up some light snow, with snow levels dipping as low as 5,500 feet on Wednesday morning. 

New Mexico:

Scattered to numerous thunderstorms will develop throughout the state on Wednesday, with a slight downtick in coverage on Thursday along with an eastward shift in moisture that will result in storms favoring the Sangres, Taos, Sante Fe, and Ruidoso while western areas see a drying trend.

Storms will be capable of producing frequent lightning and locally heavy rain.

Forecast for Fri (Aug 30) to Sat (Aug 31):

A low-grade monsoon pattern will continue across the Southwest with moisture expanding slightly westward into Arizona, Southern Utah, Nevada, and California. New Mexico, Southern Colorado, and Eastern Arizona will see the highest coverage of thunderstorms with more isolated coverage and light/spotty rainfall elsewhere.

Forecast for Sun (Sep 1) to Mon (Sep 2):

A weak trough of low pressure will move into the Western U.S. which will help to draw monsoonal moisture further north. Utah and Colorado will see an uptick in scattered thunderstorm coverage, while the Northern Rockies and Pacific Northwest will also see some isolated showers and thunderstorms.

Moisture levels will not be as significant compared to recent weeks, and this will likely be more of a scattered to isolated afternoon thunderstorm setup with spotty rainfall. 

Wildfire and Smoke Outlook:

Idaho is the current hot spot for large and active wildfires, and intensity has increased due gusty winds and warmer temperatures. Smoke from these fires will blow into Wyoming and possibly Northern Utah and Colorado from late Wednesday and into Thursday as winds shift to west/northwest (blowing from the west/northwest).

High-Res Smoke (Sky) Forecast for 7pm Wednesday:

Toward the end of the week, winds will shift back to southwesterly, which should lead to decreasing smoke in the Central Rockies with a possible uptick in smoke over Montana.

Warmer and drier conditions in the forecast for this weekend and next week, along with a threat of dry thunderstorms could lead to an uptick in fire activity and intensity across parts of the Interior West as we head into early September. 

Outlook for Tue (Sep 3) to Sat (Sep 7):

Above-average temperatures are expected throughout the West, with well above-average values possible across the Far West in particular. In other words, summer is not over yet. 

In terms of moisture, the Northern Rockies will hang onto isolated thunderstorm chances early in this period as a weak trough moves across the area.

The Southern Rockies/Southwest will also hang onto isolated thunderstorm chances as a low-grade monsoon continues, and this activity will likely favor New Mexico and possibly Arizona and Southern Colorado. 

Thanks so much for reading! Next update on Friday (August 30).

Alan Smith