On Thursday afternoon, the Tri-Cities Airport reached 110° for the first time in five years, but it didn’t stop there. Preliminary data from the National Weather Service shows the airport in Pasco reached a high of 111°, solidly beating the old record for July 30 which was 107° set in 2003. The Tri-Cities aren’t the only ones to experience record breaking heat, either. Pendleton hit 109° (old record 107° from 1929), and Walla Walla hit 108° tying their record.
Of course, the climate sites in Pasco, Pendleton, and Walla Walla weren’t the only ones roasting under copious sunshine. The WSDOT Site at Horn Rapids (where SR 240 and SR 225 meet) reached 112°, which seems to be the hottest reliable reading in the Columbia Basin. A station east of Hat Rock State Park that is maintained by Union Pacific Railroad recorded 113° seems questionable to me. Another one, this time north of Touchet, recorded 112° also seems suspect. Both of these very well could be accurate, but it’s hard to tell.
The primary culprits behind the regional heatwave are an upper level ridge of high pressure over the Western United States and a robust low pressure system located in the Pacific Ocean around 140°W (the Tri-Cities is at 119°W and the coast is about 124°W). If the low wasn’t there, we would likely still be warm because of the ridge, but the low gave that extra boost to temperatures Thursday.
In the Northern Hemisphere, air flows around low pressure systems in a counterclockwise direction. With the low west of Washington, it pulls air into the region from the southwestern part of the country. That region is also experiencing hot temperatures and the low is sending them into the Inland Northwest.
Another round of record high temperatures are possible Friday afternoon, but it seems unlikely that the Tri-Cities will hit 110° again. The ridge of high pressure is expected to start a slow trek eastward starting Friday and will allow the low to move slightly closer to the coast. This will moderate temperatures west of the Cascades and initiate a marine push that should start crossing the mountains in the afternoon and evening hours.
A lot of times when a marine push is discussed in our region, it refers to situations along the I-5 Corridor where low clouds and mist coming off the ocean cool cities like Seattle and Portland to the 60s or 70s in the middle of the day in the summer and that isn’t the kind of thing we can expect here. Being several hundred miles from the coast, the marine influence won’t be that strong in the Columbia Basin. It will, however, be strong enough to increase the wind (gusts to around 25 mph) and drop our temperature. Thanks to this push, highs Saturday should be 5°-10° cooler than Friday’s mid-100s.
The featured image is a screenshot from one of the first Mario Party games.
2 Comments
Thanks for your explanation of the factors driving our weather. You help me understand why the weather behaves as it does.What does the pressure gradient look like between the high and the low?
The gradient is strong enough to give us the flow we needed to get as hot as we did, but it isn’t exceptionally strong. Part of this is because of how far apart they are. The ridge axis is over the Four Corners region while the low is centered something like 700 miles offshore. The gradient is a bit tighter within about 300 miles of the low’s center, but that’s quite a ways away from here. Thanks for reading! I’m glad I can help you understand the weather a little better!