Nov. 8—A winter storm that proved challenging to forecast this week is now expected to bring 4 to 8 inches of snow to Anchorage before switching to rain, according to a new update early Wednesday afternoon.
That total could be much higher if lower temperatures allow snow to continue through the night, delaying the transition to rain until Thursday morning, forecasters said.
That's a significant departure from the minor accumulation of about an inch throughout the Anchorage Bowl that the National Weather Service was originally predicting Wednesday morning — and par for the course for this storm that's eluding the usual meteorological models.
The Weather Service took the relatively unusual step during a briefing Tuesday to describe two separate scenarios, one involving far more snow and the other rain. The agency's prior predictions Tuesday called for "heavy precipitation" either as rain or snow.
By Wednesday morning, it looked like Anchorage might dodge the worst of either form of precipitation. But that later changed. By noon, forecasters said, it was looking like heavier snow would start midafternoon and last until about 10 p.m.
A winter weather advisory in place for the Anchorage area is calling for additional snow accumulations of 3 to 6 inches with locally higher amounts along the Anchorage Hillside, followed by heavy rain on snow and ice during the night and into Thursday morning.
Any precipitation is expected to change to rain by Thursday morning, according to the Weather Service. What remains unclear is whether it will switch over sooner, around midnight Wednesday. The later the switch, the more snow could fall, potentially leading to much higher totals.
Conditions were still expected to warm up Thursday. The weather service issued a flood watch for the Anchorage Bowl from Wednesday evening through Thursday afternoon. "Rain on top of snow will lead to ponding of water on area of roadways," the watch said. "Excessive runoff may result in flooding of low-lying and flood-prone locations."
Roads may be slick and slushy late Wednesday and Thursday in the Anchorage Bowl, but temperatures are expected to drop again by Friday, leading to the potential for slick roads and sidewalks.
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Temperatures were staying somewhat higher Wednesday in the Matanuska Valley, which includes the cities of Palmer and Wasilla. There, the forecast called for a mix of rain and snow during the day and into the night, with a shift to all rain by Thursday morning and little or no snow accumulation.
A winter weather advisory still in place for the Susitna Valley was calling for additional snow accumulation of up to 4 inches from Talkeetna south and west as well as a layer of ice along the Parks Highway from Willow to south of Talkeetna.
Prince William Sound was getting hit with heavy snow and wind Wednesday morning, according to meteorologist Michael Kutz. Up to a foot of snow was possible from Turnagain Pass to Summit Lake before precipitation was expected to change to rain late Wednesday afternoon, according to a winter weather advisory issued for the area.
The Copper River Basin was expected to see some of the heaviest impacts from the storm, with up to 16 inches of snow possible with a transition to a mix of rain and snow later on Wednesday, according to a winter storm warning. A blizzard warning for Valdez said up to 28 inches of snow was possible there, paired with 45 mph wind gusts.
The storm system moves into Southcentral Alaska on the tail of Anchorage's first major snowfall of the season. The National Weather Service recorded a little over 6 inches of snow in the city by Sunday afternoon, which broke the previous Nov. 5 record of 3.8 inches set in 1964.