Tuesday, November 7, 2023

October Climate Data

Rick Thoman has a nice write-up of October's Arctic and Alaska climate anomalies here:


The precipitation contrasts across Alaska were striking: it was much drier than normal for the time of year in the southwest and south-central, but the North Slope and eastern Alaska were notably damp.  Rick notes that the Utqiaġvik CRN site measured 1.68" of liquid-equivalent for the month - the highest on record there for October (at either the CRN site or the much longer Barrow/Utqiaġvik climate site).  It's also the fourth consecutive month with more than an inch of precipitation at the CRN location.

Snowfall was also relatively abundant in eastern Alaska: as high as 19" in Tok and 17" in Eagle.  Also 18" on Keystone Ridge outside of Fairbanks.

Here's a look at snow water on the ground at 5-day intervals through the month, expressed in terms of historical percentile, and estimated by the ERA5 model:

The snowpack was established on October 6 in Fairbanks (considerably earlier than normal), but very little snow remained by the end of the month in the southwestern quadrant of the state.  The last week of the month was very mild, but chilly weather earlier in the month allowed for a near-normal monthly average temperature for much of the interior.  The Aleutians, North Slope, and Southeast were notably warmer than normal, however.

As for wind, October was relatively calm for the southwest and south-central, but windier than normal in the north and northeast.

Here's the mid-atmosphere pressure pattern that contributed to the surface climate anomalies: the ridge over southwestern Alaska explains the dry and calm weather there.

Sea surface temperatures remain much higher than normal in the western Bering Sea and northwestern North Pacific, so we can expect that winds from that direction will tend to bring unusually mild conditions to Alaska in the coming months.

Given that we have a strong El Niño in play this winter, which tends to produce a strong Aleutian low and frequent southwesterly flow across Alaska, I'd say the chances of a very mild winter are much higher than normal.  NOAA's Climate Prediction Center agrees:

For a comprehensive discussion of the winter outlook, check out Rick Thoman's November 17 presentation here:


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