Deep low moving across Alaska

Deep low moving across Alaska

A low-pressure system is making its way toward western Alaska and is expected to bring snow to the interior of the state Wednesday and Thursday. Winter Storm Warnings are out for areas between Nome and Fairbanks, with Winter Weather Advisories surrounding that. This is coming just days after the first snowfall of the season fell in Anchorage. As it moves north, a high-pressure system in Russia will keep the low’s center within United States territory.

Hurricane Ophelia at peak intensity. (Source: Wikimedia Commons; NASA)

The low, which this morning was located in the Aleutian Islands, has a minimum central pressure of 956mb. To give you an idea of how low that is, the ‘normal’ sea level pressure is 1013mb. The air inside this low has the same air pressure as a normal day at 1600 feet in elevation. Furthermore, Hurricane Ophelia, which struck Ireland and the United Kingdom earlier this year, maxed out as a category 3 hurricane with a minimum pressure of 960mb.

This low covers a much larger area than Hurricane Ophelia did, however, which means two things: that its impact will be felt across much of Alaska and parts of the Russian Far East and that it won’t have winds as strong as a category 3 hurricane. Don’t get me wrong, winds will be strong, but as winds are stronger when the pressure difference is more intense, hurricane force winds are not expected with this storm.

Choppy seas are expected through the Bering Strait and the Gulf of Alaska as this low moves north into Alaska. Waves in excess of 20 feet tall are expected to occur on both sides of the Aleutian Islands, with these waves continuing in parts of the Gulf of Alaska through Friday.

Thursday weather forecast for Alaska. (Source: NWS)

The low’s minimum pressure might be climbing, but that doesn’t mean its impacts will lessen. The Anchorage area is currently under a High Wind Watch, where wind gusts tomorrow could approach 80 mph. Rain showers are possible as the low moves northward, and a bit of snow might mix in. The bulk of the precipitation will be toward the northwest, though. On the Seward Peninsula, a Winter Weather Advisory is out calling for up to 4 inches of snow and winds up to 35 mph.

The bulk of the snow will, of course, occur where the Winter Storm Warnings are. Galena is looking at up to 8 inches of snow. With all this talk of snow, though, it’s important to note that this is a warm system. Even interior areas such as Galena are expecting lows in the mid-20s.

Russian weather alerts Wednesday morning. (Source: РОСГИДРОМЕТ)

The Russians have Yellow Alerts for Wind in effect for Anadyr and points east. Yellow Alerts are similar to Advisories in the United States. Winds are expected to be around 10-20 mph in Anadyr itself, with stronger winds expected closer to Alaska. Yellow Alerts for wind are also in effect for some areas around the Sea of Okhotsk. This is due to another low behind the one currently approaching Alaska.

GFS wind and air pressure for Sunday morning. (Source: Pivotal Weather)

This second low is expected to move away from Russia and approach Alaska this weekend. It will be responsible for another wind storm and round of precipitation, which has the potential to last until Halloween. Highs in Anchorage this weekend are expected to remain above freezing, in the low-40s. Fairbanks will be about 5-10 degrees cooler, with some snow and freezing rain possible. The GFS has this low following about the same track as the first before merging with a system over the North Slope and heading east into Canada.

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