Some residents in the higher hills of Seattle and Issaquah experienced tropical weather overnight, with warm, moist air pushing temperatures up as high as 70 degrees by Friday morning.
Everyone else was in the 50s, says KPLU weather expert Cliff Mass, a professor of atmospheric sciences at the University of Washington.
Hurricane Oho
He says it was the effects of Hurricane Oho, which has been moving toward us all week.
“It felt like you were in Hawaii,” Mass said of those upland areas. “And in fact some of the air from the subtropics moved up into our area before Hurricane Oho moved offshore.”
It brought offshore flow into our skies that sank into the Cascade Mountains, creating a layer of very warm air.
“It was this huge inversion over the city,” Mass said.
But by Friday morning, Oho was moving north hundreds of miles offshore of British Columbia and weakening.
“We’re not going to be affected by it all,” he said. “It’s no longer a hurricane. It’s already made the transition.”
Expecting Rain
A weak front coming in behind Oho is expected to bring rain and a few showers in on Friday afternoon, Mass said. Saturday will be the really wet day of the weekend, he said.
“A much stronger front is coming in with lots of sub-tropical moisture – so there’ll be probably a few inches in the Olympics and North Cascades, maybe a third of an inch in Seattle and the Puget Sound lowlands. So generally a rainy day, but most of the rain will start after around 10 or 11 [a.m.],” Mass said, with the likelihood of dry weather earlier in the morning.
Save Outdoor Plans For Sunday
Sunday should be the nicest day ahead, Mass said.
”No fronts, very little rain – maybe a sprinkle or two in the morning – partly cloudy skies, temperatures getting into the mid-60s,” he said. “So, Sunday is definitely your best bet.”
By Monday, it will be back to the wet pattern, Mass said, as another weak front comes through bringing more rain with it.
The weekly KPLU feature "Weather with Cliff Mass" airs every Friday at 9 a.m. immediately following BirdNote, and twice on Friday afternoons during All Things Considered. The feature is hosted by KPLU Environment Reporter Bellamy Pailthorp. Cliff Mass is a University of Washington Professor of Atmospheric Sciences, a renowned Seattle weather prognosticator, and a popular weather blogger. You can also subscribe to a podcast of “Weather with Cliff Mass” shows.
