A beautiful early fall pattern is taking hold across most of the West this week following a wet and stormy Labor Day weekend. Fire activity and smoke have also tapered off substantially. The main area of storminess from Wed to Fri will be across the Northern Rockies. Heading into the weekend, the eastern slopes of the Rockies from MT to CO will be most favored for showers/storms.
Short Term Forecast
We're coming out of a cool and wet holiday weekend across the West, but the moisture certainly had its benefits as fire activity and smoke conditions have been significantly reduced. In fact, most areas of the West should stay smoke-free over the next several days at least.
As far as the weather pattern goes, the Labor Day system has exited and the North American Monsoon has weakened substantially.
The jet stream will still remain stretched from the Sierra to the Northern Rockies. Shortwave disturbances tracking along the jet stream will tap into lingering moisture to result in daily rounds of showers and thunderstorms across the Northern Rockies with drier conditions across the Four Corners and West Coast states.
Temperatures over the next 5 days will be gradually trending warmer for most areas. Overall, temperatures over the next 5 days will be near to below average across the West Coast and into portions of the Great Basin and Northern Rockies. Temperatures will be above average across the Southwest.
Forecast for Wednesday:
Isolated to scattered showers and thunderstorms can be expected across Nevada, Idaho, Eastern Oregon, Western Montana, and Western Wyoming. Most areas will see only light and spotty rainfall.
A disturbance moving across Western Canada will also result in scattered showers and thunderstorms across BC and Alberta. Some light showers may also reach the Olympic Peninsula in Washington.
Further south, dry conditions are expected across the Four Corners states.
Forecast for Thursday:
Scattered showers and thunderstorms will favor Central Idaho and Western/Southern Montana. Most other areas will be dry and sunny, though a little bit of monsoonal moisture will reach New Mexico with isolated thunderstorms possible.
Forecast for Friday:
More widespread showers and thunderstorms can be expected across Montana, with isolated to scattered activity in Eastern Oregon, Idaho, and Northwest Wyoming. A few isolated thunderstorms are possible across Southern New Mexico, but otherwise, the Southwest looks dry.
Forecast for Saturday to Sunday:
A cold front is expected to slide down the eastern side of the Continental Divide during this period with scattered showers and thunderstorms favoring the Eastern Rockies and adjacent plains in Montana and Wyoming on Saturday. High elevation snow is also possible in areas such as the Wind River, Beartooth, and Bighorn Ranges.
On Sunday, showers/thunderstorm activity is expected to reach the Front Range and areas near/east of the Divide in Colorado and Northern New Mexico.
Outlook for Monday (Sep 11) to Friday (Sep 15):
Next week, additional disturbances and cold fronts are projected to slide down the east side of the Continental Divide, which will favor the easternmost ranges of the Rockies for additional showers and thunderstorms, and possibly some high-elevation snow.
Meanwhile, a weak influx of monsoonal moisture is also possible into the Southwest, resulting in a better chance of showers and thunderstorms across the Four Corners region – albeit to a lesser extent than what we usually see during the summer months.
Drier conditions are expected across the West Coast.
Temperatures are expected to be warmer than average for all areas west of the Divide, while areas east of the Divide in Wyoming and Colorado are expected to see near to possibly below-average temperatures.
Thanks so much for reading!
My last post of the summer season will be on Friday (September 8), then we will start to transition into fall and winter mode.