Wednesday (June 3):

A cold front will sweep across the Pacific Northwest with rain showers developing across Washington, BC, Northern Idaho, and NW Montana. Most areas will see lighter rain amounts in this region (less than a quarter inch), but locally heavier rain showers of a half-inch or more are possible across the Interior of BC

Low-level moisture has also increased across New Mexico in response to multiple low pressure areas located over Mexico and the Southwest. This will result in scattered showers and thunderstorms, with stronger storms capable of producing localized rain totals in excess of a half-inch.

Thunderstorms will also develop across the Colorado Rockies early on Wednesday afternoon, with our StormNet Model favoring the San Juans and Front Range for the highest lightning probabilities. However, only light and spotty rainfall is expected with most storms in Colorado. 

While initial thunderstorm development will occur over the higher terrain, there is a chance of mid-afternoon thunderstorms drifting across the Denver Metro Area and I-25 corridor as well.

StormNet highlights a slight risk of large hail (1+ inch in diameter), with the main threat expected across the northeast metro area around DIA and further east out on the plains. Moisture levels are also a bit higher aross the I-25 corridor and northeast plains, so locally heavy rain is possible if any stronger storms develop. 

Thursday (June 4):

The Pacific Northwest will remain in an unsettled weather pattern as a second stronger low pressure trough pushes into British Columbia. Rain showers will favor BC eastward to the Canadian Rockies, as well as the northernmost portions of the Olympic Peninsula, Cascades, and NE Washington/Northern Idaho. 

Further east, a relatively weak cold front will move across Montana, bringing gusty winds with shower chances primarily favoring areas east of the mountains, with fewer/lighter showers in the mountains. A few thunderstorms couldn't be ruled out in Montana, but the overall threat is low. 

Further south, the airmass will stabilize compared to prior days. Isolated early afternoon thunderstorms can still be expected across New Mexico as well as the Southern San Juans and Sangre de Cristos in Colorado. Most storms will only produce light and spotty rain, though some local downpours can't be ruled out. 

Central and Northern Colorado look drier and more stable, and while a stray afternoon thunderstorm couldn't entirely be ruled out, the overall threat is quite low. 

Friday (June 5):

In the Pacific Northwest, a trough will deepen southward into Washington and Oregon, and a cold front will also move across the Cascades. Rain will become more widespread and heavier along and west of the Cascade Crest, and across the Interior of BC.

Snow levels will also dip to around 4,500 feet in the Washington Cascades, with snow accumulating across the higher terrain.

New Mexico will see isolated to scattered thunderstorms again on Friday, with most storms producing light and spotty rain (localized heavier rain is still possible, though).

Colorado will see a lower threat of thunderstorms overall, with isolated activity largely confined to areas south of I-70.

Saturday (June 6):

The Pacific Northwest will continue to see wet conditions heading into the weekend as a trough continues to deepen across the area. The heaviest rain is expected along and west of the Cascade Crest and across the Interior of BC, with lighter rain for Eastern Washington.

Snow levels will also dip to around 6,000 feet across the BC Interior and Canadian Rockies as a cold front progresses inland.

Ahead of the cold front, a chance of thunderstorms is expected across the Northern Rockies, though the highest threat is likely along and east of the Continental Divide, where instability will be greater.

Further south, thunderstorm chances will increase across the Colorado Rockies, with an even higher threat across the Sangre de Cristos in New Mexico. Most storms in the Southern Rockies will produce light and spotty rain, though isolated downpours can't be ruled out. 

Sunday (June 7):

The main trough will lift northeast across the Northern Rockies on Sunday, and a cold front will also move through, favoring showers across Montana, NW Wyoming, and Southern BC/Alberta.

The Pacific Northwest may see a break during the day on Sunday, but another trough is projected to arrive on Sunday night with rain possibly developing along the West Coast again overnight. The timing is still subject to change this far out, however, so stay tuned. 

Thunderstorm chances will be highest east of the Continental Divide on Sunday, and especially out on the plains of Montana, Wyoming, and Colorado.

However, StormNet is also picking up on a lightning risk across Northern and Central Utah as the cold front approaches, including the Wasatch. 

5-Day Precipitation Totals:

We are not expecting massive rain totals by local standards across the PNW with this upcoming pattern. Rather, it will involve frequent rain showers that will add up to respectable amounts over time in some areas, along with generally wet conditions. 

Our PEAKS Model is projecting rain totals in excess of one inch across favored areas in the Washington Cascades, BC Coast Range, and BC Interior Ranges over the next 5 days, with light to moderate totals across the Oregon Cascades and West Coast. 

Monday (June 8) to Friday (June 12):

The main change since my last post is that medium-range models are trending toward a stronger and more persistent trough setting up over the Northwest U.S. next week.

As a result, we are seeing a cooler and wetter signal emerge across the Pacific Northwest and Northern Rockies, with shower chances possibly extending into the Sierra and Northern California, as well as across Northern Utah.

Further south, we're continuing to see a modest signal for pesky afternoon thunderstorms in New Mexico and Colorado, similar to this past week. Above-average temperatures are also expected in these areas, but not excessively so.

June 13th and Beyond:

We are seeing some hints of a high pressure ridge building along the West Coast around mid-month, which could bring a period of above-average temperatures and dry conditions from California to the PNW and portions of the Interior West.

However, early indications are hinting that this may not be a long-duration ridge.

As El Niño conditions emerge in the Pacific, this will favor a more active upper-level pattern along the West Coast and Interior Western U.S., though oftentimes, high-pressure ridges set up further north over the PNW and Canada, so this will be something to keep an eye on as we head deeper into the summer.

Thanks so much for reading! Next update on Friday (June 5).

Alan Smith