Saturday, February 12, 2022

Snow Survey and January Climate Data

Yesterday I came across the February 1 snow survey report from NRCS, and it provides a useful and readable summary of Alaska's winter so far, at least from the perspective of temperature, precipitation, and snowpack.  Here's the February 1 NRCS snowpack map, showing far above normal snow water equivalent in the central interior, and above normal nearly everywhere that snow is measured (which is very far from everywhere).

Here's the general overview text for snowpack (click to enlarge); take a look at the report itself for separate comments on temperature and precipitation, and regional snowpack summaries.

While the "percent of normal" snowpack map is obviously very illuminating, I like to view the percentile map to see where conditions are near or exceeding records.  The following map (click to enlarge) shows SWE percentile with a minimum of 15 years of historical data.  There's a lot of blue, indicating record or near-record high snowpack, from the Koyukuk and middle Yukon drainage to the Chena and Upper Tanana areas and the Copper River basin.  Uncolored markers have less than 15 years of data, but no doubt many of those locations have very high snowpack too.  The only spot with notably low snow being reported is in the middle Chugach near Valdez.

Here are January climate anomaly maps from NCEI's climate division data and ERA5 data, showing the percentile rank compared to the prior 30 years.  According to the ERA5 model data, it was an unusually windy month in much of the state.

Rick Thoman's temperature map confirms that January temperatures were close to normal overall in much of the interior, but significantly lower than normal in the Arctic and western Alaska.  Utqiaġvik came in with marginally above-normal temperatures for the month, and interestingly this doesn't seem to have been captured by the gridded ERA5 data.

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