Terri-Ann Betancourt of Puget Sound Energy said the number of customers without power had been whittled down to about 79,000 by 1 p.m. Sunday.
But she said gusty winds from the incoming storm already were causing new power outages in the Snoqualmie and North Bend areas - and the number could continue to grow if, as expected, winds pick up and become more widespread.
"With all the ice and snow and freezing rain, we've got trees that are really vulnerable to coming down," she said. "The windstorm just adds to the problem."
Since early Wednesday, PSE crews have restored power to more than 325,000 customers in Western Washington.
In Tacoma, about 600 to 800 still were without power. In Snohomish County, about 900 remained without electrical service.
At the height of the ice storm on Thursday, more than 300,000 customers lost power across Western Washington as the weight of snow and ice brought down trees and branches across power lines.
About 250 crews brought in from as far away as Arizona and Colorado are working full-time since then to repair damaged lines and restore service.
Puget Sound Energy, the area's largest electrical utility, hopes to have power restored to the vast majority of homes by Sunday night.
But people living in more remote or forested areas may not get their power back until Tuesday or Wednesday or even later, utility officials said.
View an area-specific list showing when service is expected to return in different communities >>
It was unclear exactly what effect another incoming Pacific storm might have on power restoration efforts. The weather system is expected to generate rain and strong winds Sunday afternoon and evening across much of Western Washington.
Winds would gust up to 60 mph in northern areas of Western Washington and along the coast, according to the National Weather Service. The east Puget Sound lowlands could see gusts of up to 50 mph.
As of 4 p.m., winds were gusting to 45 mph at Friday Harbor in the San Juans, 48 mph at Oak Harbor on Whidbey Island and 41 mph at Bellingham in Whatcom County.