Monday, October 1, 2018

Alaska Mega-Ridge Persists

October has arrived, but you wouldn't know it based on the weather conditions across Alaska, as most of the state continues to be gripped by a most extraordinary spell of warm, dry, and clear weather.  The culprit is another intense ridge of high pressure aloft, very similar to the one that set up over the Bering Sea in the first half of September.

Here's the 500mb chart from Saturday afternoon, exactly 3 weeks after the chart that I showed in my mid-September post.  Click to enlarge.  Note that the 500mb height at Fairbanks was 5800m, which is the latest in the year that such high pressure has been observed at this mid-atmospheric level above Fairbanks.


Rick Thoman has pointed out some of the impacts of the unusual weather pattern in his Twitter feed (embedded at right).  This includes a number of significant high temperature records such as 71°F yesterday at King Salmon - the warmest on record for so late in the season.

It's also interesting to note that downsloping to the southeast of the ridge has produced some remarkable warmth in southeast Alaska, including 66°F with clear skies for 3 days in a row in Yakutat (also the warmest on record this late in the season).  According to the long-term history, this is the very wettest time of year in Yakutat, with about 0.7 inches of rain per day on average.  It doesn't usually look like this:


Here's a really stunning photo from the Suomi polar orbiter shortly after noon yesterday.  The link below the image takes you to a larger file (2MB size) - what a view!  The only real low-elevation snow cover is across the eastern North Slope, although there is a bit of snow on the ground near the Porcupine River to the northeast of Fort Yukon.


http://worldagweather.com/npp.20180930.2204_true_color_cropped.jpg

Here's the view at Utqiaġvik yesterday evening, showing some patchy snow on the ground and a bit of ice on the fresh water lagoon, but no sea ice.  More on the sea ice situation in another post.


And for good measure, here's another selection of lovely webcam shots from yesterday evening.  Perusing these is, for me, the next best thing to being there!  It's hard to imagine that freeze-up and snow cover are only a few weeks away at most, assuming that the normal seasonal trajectory soon reasserts itself.

Bettles

Arctic Village

Anaktuvuk Pass

Chandalar Shelf

Point Hope in the far northwest

Kivalina

Shungnak

Koyuk - where ice will very soon be running in the river

And of course Minchumina looking towards Denali

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