A region of warmer than normal SSTs is expanding quickly westward from the coast of South America, leaving equatorial cool anomalies looking anemic in the central Pacific:
Compare with the situation just six weeks earlier:
The long-range computer models expect warming to continue through spring and into summer, resulting in El Niño by summer. This month's forecasts are more aggressive than previously, and judging from the current trend, they may not be aggressive enough.
If El Niño does develop - as seems very likely - this will be a risk factor for increased wildfire activity in Alaska this summer. However, the statistical connection hasn't always played out in recent years; 2023 was an analogous year with El Niño developing, but Alaska's fire acreage was very low (in contrast to Canada).
In the meantime, La Niña won't relinquish her influence on high-latitude patterns immediately, and the latest forecasts suggest a strong possibility of another La Niña-like persistent statewide cold spell starting the middle of next week. The cold plunge next week seems to be locked in: here are two leading ensemble models for next Thursday morning.
Looking farther ahead, the details are less clear on the evolution into March, but there are strong hints of a persistent ridge near the Date Line and a trough over eastern Alaska and northwestern Canada - very similar to the persistent pattern in December.
Below is an example: compare the forecast portion (left side of the graphic below the dashed line) to this December 18 post. The blue shading near the longitude of Alaska indicates the trough that will produce the cold northerly flow; this model shows the setup lingering into mid-March. (Note that the previous post includes an explanation on interpreting these figures.)
"Lingering", yes an appropriate term and the deep blue does remain over the longitude of Alaska until about mid-March. Ok, well first we deal with more snow then some deep cold. The problem with snow is it impacts travel, whereas cold can de dealt with even while causing related issues. But it's good to know and this does inform. And solar insolation under clear skies is helping warm the day some. Thanks Richard for the outlook...we're prepared.
ReplyDeleteDuring the most recent snow-wind event in Fairbanks this week I noticed the moisture fetch started SE of Japan, and perhaps further SW. What would cause such a far reaching source of moisture?
ReplyDeleteYes, it was a very elongated ridge across the N Pacific, with a broad trough across NE Russia. One contributing factor is likely the ongoing warm zone of elevated SSTs just to the south of the Aleutians, which fosters increased ridging and therefore more westerly flow to the north. But the SST anomaly has been there a long time. The more immediate cause has to do with the widespread low pressure over Russia, and this is likely a response to tropical convection patterns. Ironically, the overall Arctic circulation has become more classically La Nina-like lately, even as La Nina's SST signature is fading.
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