Forecast Highlights:

• Colorado & New Mexico: Daily rounds of scattered to numerous thunderstorms capable of soaking rains and active cloud-to-ground lightning.
• Utah & Arizona: Thunderstorms become less numerous with a decreasing risk of flash flooding. 
• Pacific Northwest and Idaho/Montana: Showers and thunderstorms with soaking rains Sat-Mon, and possibly strong to severe thunderstorms across the Northern Rockies.
• Wyoming & Southern Idaho: Daily rounds of isolated to scattered thunderstorms.
• California & Nevada: Mostly dry (except for far NorCal) with temps running below average.  

Synopsis:

A trough of low pressure will set up along the West Coast this weekend, resulting in several days of active weather as Pacific moisture and energy stream into the Northwest and far Northern Rockies. Meanwhile, a ridge of high pressure will shift eastward into Texas, and southerly winds in between the trough and the ridge will direct the flow of monsoonal moisture into New Mexico, Colorado, and Wyoming where daily rounds of thunderstorms are expected.

The West Coast trough will usher in cooler air with below-average temperatures expected across Oregon and California in particular. Temperatures will also be near to below average around the Four Corners region where monsoonal moisture will result in increased cloud cover.

Forecast for Friday:

Widespread thunderstorms can be expected across Colorado, New Mexico, and Eastern Arizona with more isolated activity across Northern Arizona, Utah, Wyoming, and Southwest Montana. Storms in Colorado/New Mexico will produce heavy downpours but faster storm motions should negate a significant/widespread flash flooding threat.

Forecast for Saturday:

Colorado, New Mexico, and Eastern Arizona will see scattered to numerous thunderstorms once again with more isolated activity in Utah and Wyoming. Meanwhile, energy and moisture from the Pacific trough will result in scattered showers and thunderstorms developing across the Washington/Oregon Cascades, as well as areas further east including the Blue/Wallowa Mountains along with Idaho and Montana.

Forecast for Sunday:

Scattered thunderstorms can be expected once again across New Mexico and Colorado with isolated storms for Wyoming and Eastern Utah. Meanwhile, more widespread showers and thunderstorms with heavy downpours can be expected across the Pacific Northwest and Northern Rockies, with the potential for strong to even severe thunderstorms across the Northern Rockies.

Forecast for Monday:

Showers and thunderstorms with heavy rain can be expected for the 4th of July across Washington, Northern/Central Idaho, and Montana. Drier air will work its way into Utah and most of Wyoming with a minimal risk of thunderstorms for these areas, while monsoonal moisture will remain over Colorado and New Mexico as well as Eastern Arizona with thunderstorms expected once again. 

Outlook for Tuesday (7/5) to Thursday (7/7):

The West Coast trough will begin to weaken and gradually retreat north/northwestward during this period, but pulses of moisture and energy will continue to produce occasional lighter showers across the Pacific Northwest and Northern Rockies.

Further south, the monsoonal flow will continue with daily rounds of thunderstorms across Colorado, New Mexico, and Arizona, though coverage may be less widespread compared to recent days. 

A strong ridge of high pressure will also build over the Intermountain West during this period, resulting in the start of a heat wave with well-above-average temperatures for most of the West with the greatest departures expected across the Central and Northern Rockies. 

Outlook for Friday (7/8) to Friday (7/15):

A ridge of high pressure is expected to dominate the pattern across the Western U.S. during the second week of July, resulting in hotter-than-average temperatures for most areas, except for possibly the PNW coast. 

Monsoonal moisture will remain in place across the Four Corners region with near-daily rounds of thunderstorms likely across portions of Colorado, New Mexico, Arizona, and perhaps Southern Utah. Drier conditions are expected across the Northwest, California, and Northern Rockies. 

Thanks so much for reading and have a great weekend! Next update on Wednesday (7/6).

ALAN SMITH

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