The sizzling heat of the past week could get dampened starting tonight.
Earlier today, the National Weather Service upped the chance of rain and thunderstorms to 90 percent tonight, but the latest forecast is calling for a 30 percent chance.
A low pressure area spinning off the Washington coast is creating a moist southerly flow over the Inland Northwest.
Thunderstorms will start firing up in Central Washington near the Cascades before moving east overnight, forecasters said.
The Storm Prediction Center said there is a slight risk of severe thunderstorms, which could cause damage.
The 5 p.m. temperature was 90 at Spokane International Airport. The combination of heat and lower air pressure is creating a pattern favorable to formation of thunderstorms, forecasters said.
The stormy weather continues into the weekend under the southerly flow, but temperatures will remain warm with highs near 90 on Saturday with lows in the middle 60s. Highs will be in the lower 80s on Sunday and Monday.
The greatest risk of rain arrives on Sunday with a 70 percent chance in Spokane.
During the past week, several people have been hospitalized with heat-related illnesses, including one who remains in the Intensive Care Unit at Providence Holy Family Hospital. Heather Barfield, nurse manager for the ICU, said 20 people, ages 13 to 80, have come to the hospital’s emergency room with heatstroke or heat exhaustion. After a week of highs in the upper 90s, however, Spokane is likely to see more wet weather.
Despite the heat wave that struck Spokane over the last week, Washington’s weather has been mild compared to much of the rest of the country.
Every state in the contiguous United States except Washington had warmer-than-average temperatures for June 2011 through June 2012, according to the National Oceanic Atmospheric Administration. It was the warmest consecutive 12 months the country has experienced since record keeping began in 1895.
And last month was the 10th-driest June on record, with drought spreading to 56 percent of the country, threatening corn crops in the Midwest and making it the largest drought footprint of the 21st century.
For Washington, Maine and Oregon, this June ranked in the top 10 for moisture in each state’s history. Florida, slammed by tropical storm Debby, was the only state wetter than Washington last month.
That’s because an unusually strong ridge of high pressure was sitting over much of the United States, bringing persistent dry and warm weather. In a smaller portion of the Western United States, including Washington, there was a persistent trough of low pressure that brought cooler-than-normal conditions and above-normal precipitation.
“We’re lucky,” said meteorologist Jonathon Fox. “It’s just kind of the persistence of the overall weather pattern that led to that difference.”
The hot, dry weather across the nation also led to wildfires burning 1.36 million acres during June, the second most on record for the month.
By contrast, Washington has seen a slow start to wildfire season. The cool, wet spring has kept the risk of wildfire low. Weather in July, August and September, however, is expected to be hotter and drier than normal.