WENATCHEE — Chinook winds whisked down mountain slopes here last night to push this morning’s temps into the high 40s and trigger balmy weather, including partial sun, through week’s end.

“These are snow-eating winds that arrive just about every winter season,” said Ty Judd, forecaster with the National Weather Service in Spokane. “I expect the warm temperatures to last through today — with some areas hitting nearly 50 degrees — before easing back towards normal.”

At higher elevations, recent storms have increased avalanche danger above 4,000 feet in the backcountry around Stevens Pass, according to the National Weather and Avalanche Center. Ridge crest winds, warming temperatures and periods of heavy rain or snow add up to increased risk Wednesday and into Thursday, the center’s website said. Get more avalanche details online at nwac.us.

Winds from the Pacific Coast began pouring over the Cascade ridgetops around 2 a.m. today and raced down the eastern slopes to create the chinooks, said Judd. “The air compresses as it enters lower elevations,” he said, “and that compression creates heat that makes for warm breezes” in the Wenatchee Valley.

Beginning around 11 p.m. Tuesday, the valley floor began warming at a rate to 2 to 3 degrees per hour. Overnight winds reached 14 mph with gusts up to 23 mph with conditions remaining breezy through today.

Areas beyond the immediate Cascade foothills were less affected by the warmer winds, said Judd. Temperatures today in Moses Lake were predicted to reach a seasonable 36 degrees. In Omak, temps sunk to 16 degrees and weren’t expected to top 35 or 36 later today.

Chinook conditions are expected to end by Saturday as a new high pressure ridge advances over central Washington. That could bring mild inversions and the resulting stagnant air, low clouds and patchy fog.

“But it won’t be as bad as we experienced a week to 10 days ago,” said Judd. “The ridge will be more unsettled with even a few chances for precipitation.”