A ridge of high pressure will build over the next couple days, bringing a steady climb to high temperatures across the Columbia Basin for the remainder of the week. Current indications are that highs will reach their peak Sunday with highs at or above 105°. The warmest locations will be in the lower elevations, such as the Tri-Cities and Hermiston, but most of the area appears likely to exceed 100°. This will get close to breaking the record high for Sunday, which currently stands at 106° for the Tri-Cities.
Overnight lows won’t be providing much relief, either. Thursday morning the Tri-Cities Airport recorded 49°. These temperatures are expected to climb just as fast as our highs and will only get down to the low-70s Sunday night through Tuesday night.
This heat has prompted the National Weather Service to issue an excessive heat watch for much of the Interior Northwest lowlands. This is in effect from Sunday morning to Tuesday evening. While temperatures look to peak on Sunday, the Tri-Cities should stay above 100° through Tuesday. There is a chance of this heat wave extending beyond Tuesday, but there isn’t a whole lot of confidence in the models with that right now. I’ll be sure to post updates when relevant over on Tri-Cities Weather on Facebook and my personal Twitter.
The position of the ridge of high pressure combined with a trough located offshore will provide a flow regime that will bring a low chance of thunderstorms to the basin Sunday. Southwesterly flow stands poised to send moisture from the Sierra Nevada in California north into Central Oregon. Like most thunderstorm chances for the Tri-Cities, it isn’t high enough to get excited about but is something to be aware of. The best chance of storms lies toward Pendleton and Walla Walla where the Blue Mountains help to push air up to generate thunderstorms.
Remember to drink plenty of water, to avoid direct sunlight during the day Sunday, Monday, and Tuesday, and be aware of the symptoms of heat related illnesses. Heat stroke is an emergency that warrants a call to 911.
