What's the Bay Area's risk from 'heat domes' like the one broiling the Pacific Northwest?
The Pacific Northwest is stuck this weekend under what meteorologists call a heat dome, with parts of Washington and Oregon sweltering amid unprecedented triple-digit temperatures. According to the National Oceanic and Atmospheric Administration, a heat dome is a large area of high pressure that acts as a lid, trapping hot air and essentially creating a bubble. The phenomenon is common during the summer months and usually occurs in the Four Corners region of the Southwest, where temperatures are scorching over the desert. Its an area of warm air, a high pressure dome that is a normal summertime pattern, said Ryan Walbrun, a meteorologist with the National Weather Services Bay Area office. However, this time around, Its located slightly further north than we usually expect it to be, he said. Walbrun said heat domes are hard to quantify, but during the summer months they are expected to happen from time to time in the Bay Area. One that occurred in June 2017, for example, led to several heat-related deaths in San Jose. However, For us, generally speaking the hottest time will still be in September and October when we get the offshore wind patterns, Walbrun said. The last two mornings we did have the marine layer and low clouds that brought relief to us.  He said if we dont have offshore winds, the Bay Area almost always gets the low clouds and fog that work in our favor. The concern increases for the inland areas that usually suffer the brunt of the hot temperatures throughout the summer months. But in the very near term, no severe heat conditions are expected in the Bay Area, Walbrun said. As we approach the July Fourth holiday, the pattern looks pretty typical at least for the Bay Area and a lot of the West, he said. It will be pretty warm inland...but we dont quite see the extremes in terms of really hot temperatures.  Kellie Hwang is a San Francisco Chronicle staff writer. Email: kellie.hwang@sfchronicle.com Twitter: @kelliehwang