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Under the Arctic Dome — Brutish High Pressure System is Wrecking the Already Thinned Sea Ice

There’s a real atmospheric brute towering over the Arctic’s Beaufort Sea at this time. A high pressure system that would put shame to most other anti-cyclonic phenomena that bear the name. It is sending out a broad, clockwise pattern of winds. It is pulling up warm air from the Pacific to invade the Bering, Chukchi, East Siberian and Laptev Seas. And its torquing motion is shattering the already considerably thinned ice beneath it.

(A powerful high pressure system over the Beaufort Sea is predicted to further strengthen by late April 15. Image source: Earth Nullschool.)

Clocking in at 1046 mb of pressure, it makes typically strong 1030 mb high pressure systems seem weak by comparison. Over the next day it is expected to strengthen still — hitting 1048 mb by late April 15th (coming very close to an extraordinary 1050 mb system).

Shattered Sea Ice

This powerful and strengthening system has already been in place for about two weeks — slowly gaining momentum as its circulation has moved in mirror to the waters of the Beaufort Gyre that swirl beneath it. Masked only by a veil of sea ice considerably thinned by human-forced climate change, the waters of the Beaufort are now breaking through. Streaks of dark blue on white in an early break-up enabled both by a terrible Arctic warming and by this powerful spring weather system.

(Side-by-side images of Beaufort sea ice from April 4 [left frame] to April 13 [right frame]. Note the considerable and rapid advance of fracturing in a relatively short period. For reference, bottom edge of frame in both images is 500 miles. Image source: LANCE MODIS.)

Warm Storms

On the Siberian side of the Arctic, this massive high pressure dome is drawing in warm winds from the Pacific Ocean. Gust by gust and front by front, they come in the form of squalls that deliver above freezing temperatures and rains that blanket this thawing section of the Arctic. On Thursday, April 13, these warm winds had driven northward over 2,500 miles of Pacific waters to be drawn into storms that unleashed their fury — driving rains and gales through the already dispersed ice in the Bering Sea and shattering ice floes through the Chukchi. Today, April 14, these winds and rains drove northward to assault the ice of the East Siberian and Laptev seas.

(On April 13, above freezing temperatures, rains, and gale force winds ripped through the sea ice near Wrangle Island in the Chukchi Sea. Image source: Earth Nullschool.)

A Great Atmospheric Stack Drawing Heat into the Arctic

In the past, meteorologists like Stu Ostro envisioned that climate change would tend to produce towering high pressure systems — featuring increasingly strong storms roaring about their fierce outer boundaries. And the massive high lurking over the Arctic at this time is a good example of Ostro’s predictions coming to light in a region that is very sensitive to human-forced warming.

This great atmospheric stack appears to have had a considerable impact on the ice already — helping to push extent measures back into record low ranges by accelerating the melt trend. But these impacts are likely to spike over the coming week as this powerful high expected to remain in place through the next five days — continuing to draw warm air into the region.

(Global Forecast System models predict extreme warming over the Arctic Ocean throughout the next week resulting from the influence of a powerful high pressure system and very strong associated ridge in the Jet Stream. Image source: NCEP Global Forecast System Reanalysis.)

GFS model runs indicate that average temperatures over the Arctic Ocean region will hit a peak as high as 4 degrees Celsius above average by late next week. Meanwhile, the warmest zones are expected to be as much as 18-20 degrees Celsius above average. Such abnormal warmth at this time of year, if it emerges, will put a considerable damper on a freeze that should now be continuing in the High Arctic even as edge melt ramps up with the progression of spring.

This is particularly concerning due to the fact that temperature anomalies in the Arctic tend to fall off during spring and summer. In other words, such a powerful warming trend for the Arctic Ocean would be bad enough during winter — but it is an even more unusual event for spring. An ominous start to a melt season that could produce far-reaching regional and global consequences.

Links:

Earth Nullschool

LANCE MODIS

NCEP Global Forecast System Reanalysis

Stu Ostro

Climate Reanalyzer

Hat tip to Colorado Bob

Hat tip to Andy in San Diego

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