Sun is going to drench the Inland Northwest for two more days, but a pair of low pressure systems will combine by Saturday to change the fair weather pattern that’s been in place for two weeks.
A low pressure center that’s been stalled off the California coast this week is expected to move inland today, bringing with it a stream of moist air that could trigger thunderstorms across much of the region this afternoon, especially in the southern Idaho Panhandle and southeastern Washington.
A flash flood watch was issued this afternoon for Asotin and Garfield counties in Washington and the Lewiston and Grangeville areas in Idaho. Northeast Oregon had a severe thunderstorm watch in place this afternoon, too
The change to a more southerly flow combined with weak high pressure overhead will allow temperatures to creep into the middle 80s or warmer today. Coeur d’Alene is forecast to reach 90 today. Highs in the upper 80s are expected in the Spokane and Coeur d’Alene area on Friday.
A 20 percent chance of thunderstorms is forecast for Friday in Spokane and Coeur d’Alene, and a higher chance is predicted for areas to the south. Any thunderstorms that form will be slow to move and could bring periods of drenching rain, forecasters said.
The thunderstorm risk is coming from humid air circulating off the California coast and moving northward from the Great Basin. That humid air is going to replace the cooler northeasterly breezes that have fanned the region since Monday. Forecasters said sultry conditions are likely starting tonight and again on Friday.
Dewpoints have been in the upper 20s and lower 30s this week - a good measure of how dry the air has been. Forecasters said the dewpoint should rise into the middle 40s on Friday.
The result should be an increase in billowy cumulus clouds on Friday, and possible showers or thunderstorms by late afternoon.
Then, a new system moving southward from Canada should sweep cooler air into the region overnight on Friday. By Saturday, highs will return to near-normal temperatures in the low 70s under partly cloudy skies. On Sunday, forecasters are predicting a mostly cloudy day with highs in the middle 70s. Lows both nights should be in the 40s.
At 7 a.m., mild temperatures were reported across the region with 61 at Spokane International Airport, 65 in Cheney, 61 in Sandpoint and 62 in Coeur d’Alene. Pullman was warmer at 67.
Sunrise Friday will be at 4:54 a.m. and sunset tonight is at 8:43 p.m. The summer solstice is on June 20 at 10:46 p.m., the start of summer.