Thursday was probably the last warm day for a while

It's been a week of extremes — record rainfall, summery sun and record highs — but don't expect to see uncommon weather from here on out.

After record rainfall for Nov. 1 on Monday, Seattle had glorious sun on Wednesday with the official high temperature at Sea-Tac airport reaching 74 degrees, tying the record high for the month of November. And it got as high as 76 degrees at the National Weather Service's Sand Point office on Wednesday.

Thursday wasn't quite a repeat. The official high at Sea-Tac was 65, while it got up to 70 degrees at Sand Point. But the sun was shining. The sky was blue.

Savor the memory. On Friday, dreary fall weather returns. We likely won't see any more such days until spring. That's the word from University of Washington meteorologist Cliff Mass.

"It drops into the mid-50s and it never goes back into the 70s," Mass said Thursday afternoon. The rain is expected to arrive quickly and will continue in full force, he warned. November is typically the wettest month of the year, with the fourth week being particularly soggy.

Though the past week's weather pattern seemed unusual, National Weather Service meteorologist Ni Cushmeer said the wild swings we've seen this week are fairly common for the Puget Sound area, especially during seasonal transitions.

Cushmeer said the jet stream — strong air currents that flow west to east at about 35,000 feet and influence the weather — shifts more often during fall and spring. Both are transitional seasons characterized by both warm and cool weather.

On Monday, Cushmeer said, the jet stream moved south and rain clouds settled over the Sound. The next day, the jet stream shifted back to the north, which caused air to sink and increase in pressure. Then, a flow of wind moved from the Cascades to the lower altitudes in the western part of the state and further compressed the air, causing the temperatures to rise.

Such meteorological mood swings are common in these fall months, Cushmeer said. The only unusual part of the week was the record-breaking heat.

"Always keep in mind that the weather is never 'normal,' " Mass said. "It's always wetter than normal and drier than normal. The times when it's actually 'normal' are few and far between."

According to Cushmeer, the high temperature will be just 54 degrees on Friday, and it will hover in the 50s for the next few days. Rain will fall on and off.

And for the Northwest, that's as "normal" as it gets.

Jill Kimball: 206-464-2136 or jkimball@seattletimes.com