A Pacific storm system is expected to arrive over the Inland Northwest today and bring a major change to the sunny, warm weather in recent days.
“Cool and rainy conditions are expected to persist into Friday with the potential for significant three-day rain totals for North Idaho and Northeast Washington,” National Weather Service meteorologist Greg Koch said in a briefing Monday.
An upper-level low-pressure area will move into the region today, bringing clouds and a 50 percent chance of showers and thunderstorms. By tonight, the chance of rain and storms climbs to 80 percent.
Temperatures today will remain above normal for this time of year as the low-pressure system initially circulates warm air northward into the Inland Northwest.
The heaviest rainfall will likely be on Wednesday, lingering into Thursday and Friday. The low-pressure system is expected to migrate inland across northern Oregon and then swing northward into Eastern Washington and North Idaho.
The low-pressure system should help soak parts of the Columbia Basin where wheat and other grain crops are in need of a good dousing to get them to mature properly. Ritzville may see 0.42 inches of rain while Wilbur is forecast to get 0.57 inches on Wednesday and Thursday.
In Spokane, forecasters call for 0.96 inches of rain from the storm on Wednesday and Thursday.
Other two-day rain forecasts are 1.3 inches in Coeur d’Alene, 0.64 inches in Pullman, 1.49 inches in Sandpoint, 1.4 inches in Kellogg and 1.25 inches in Colville.
Coeur d’Alene could see its heaviest rain during the day Wednesday.
Forecasters said the showery nature of this week’s precipitation may result in some areas getting more rain and other areas getting less rain than predicted.
High temperatures in Spokane will drop to the upper 50s and lower 60s on Wednesday and Thursday before starting to rebound by Friday and Saturday.
Forecasters said the low-pressure area that is bringing the wet weather is likely to stall over the region, allowing a rain band to form along its leading edge from north-central Washington to southeast Washington. That will bring rain to all of the Spokane area, North Idaho and Western Montana.
Some areas to the north of Coeur d’Alene and Spokane could see up to 2 1/2 inches of rainfall, forecasters said.
The heavy rain could bring rises in small rivers and streams, forecasters said, and the soaking rains should slow down the arrival of wildfire season. Heavy rain near burn scars in Central Washington could result in localized flash flooding.
This comes after a short stretch of summerlike weather over the weekend. Sunday’s high was 85 in Spokane.
Normal temperatures for mid-June are 74 for the high and 51 for the low.
The weather outlook for June 25 through July 1 calls for normal precipitation and above-normal temperatures.
“Warmer and drier weather should arrive just in time for the weekend, but a return to showers and thunderstorms will be possible once again by early next week,” Koch said.