Polar jet connects Alaska record with California rain and snow



Snow tops the peaks of Sequoia National Park.

Last week, a large 592 decameter high pressure system developed about 2,200 miles west of Washington State. I have been forecasting since 1991, and I cannot recall such a powerful ridge in this region in winter.

It deflected high-altitude winds (jet streams), like a boulder in a fast-moving stream, northeastward over the Aleutian Islands to Alaska. These high winds brought a mass of relatively warm and humid air to the northernmost state of the United States.

According to a tweet from the National Weather Service Alaska region on December 25, 2021: “The Kodiak Tide Gauge station recorded an incredible temperature of 67 ° F yesterday. This is a new statewide temperature record for December. Kodiak Airport recorded 65 ° F. This broke their monthly record of 9 ° F! The weather balloon launched at the same time confirms these astonishing readings. “

Not only did this warm, humid air mass break temperature records, but also precipitation milestones. You see, for or each degree Fahrenheit the air heats up; it can contain about 4% more water.

December 25 saw nearly 2 inches of liquid equivalent precipitation in Fairbanks, the city’s wettest December day on record.

After the polar jet left Alaska, it headed straight south along the west coast of the United States. It brought record amounts of snow in December to the Sierra Nevada.

UC Berkeley Central Sierra Snow Lab at Donner Pass reported 212 inches, or nearly 18 feet, of snow for December 2021. This is the snowiest December on record at this location.

In Atascadero, John Neil of Atascadero Mutual Water Co. saw 8 inches of rain, the sixth wettest December on record. As of December 30, Rocky Butte had recorded more than 26 inches of rain, more than half of its seasonal average (July 1 to June 30) of 40 inches. In fact, many places on the central coast have already recorded more rain this rainy season than the entire season of last year.

In December, rain and snow significantly reduced the severity of the drought in California from “D4 exceptional” to “D2 severe / D3 extreme”. The Central Coast has gone from a “D3 extreme” classification to a “D2 severe” classification.

Unfortunately, the eastern Pacific high is expected to leave the central coast of California next week. This will force the high altitude winds and the storms they bring to northern California, Oregon and Washington for much of the first half of January.

A significant oceanographic event will take place on Saturday, Sunday and Monday: the King Tides. These tides are among the highest and lowest of the year, spaced less than 12 hours apart. At 8:38 a.m. on Sunday, high tide is expected to reach 7.1 feet at the Port San Luis tide gauge near Avila Beach. This is the highest tide I have ever seen. This high tide will be followed by a low tide of 1.9 feet at 4:10 p.m., a huge sea level change of 9 feet in less than 8 hours!

If you remember my column from the end of November, there can be a big difference between the predicted sea level and the actual sea level when the sea is not at rest or when the water temperatures are seas are warmer or colder than usual.

PG&E Safety Message

If you are heading out to the ocean to observe these tides, be careful and remember the cardinal rule, never turn your back on the sea.

The dangers associated with heavy snowfall include a high avalanche risk, cold temperatures, the risk of traveling over mountain passes and highways, and the danger of snow load that can cause falling trees. and power lines.


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