Tuesday, 26 March 2019

Extreme heat forecast for the Arctic


Extreme Heat (for late March) in Arctic Likely The Next Two Weeks

Nicholas Humphrey
26 March, 2019

I've posted the past few days about the significant heat wave the Arctic will see this week into next week. But those maps have been temperature anomalies. Here are the latest actual temperature forecasts (Every 7 am CDT, Tuesday-Monday). Temps in many areas will be 27-36 degrees F (15-20 C) above normal and likely greater in isolated areas. This is the product of a very wavy jet stream (caused by regional Arctic Amplification of global warming) weakening the Hemispheric temperature contrast between the poles and mid-latitudes, leading to a weaker, wavier jet stream. This feeds back into producing either intense upper-atmospheric ridges of high pressure (such as the "heat dome" over Alaska) or intense storms, coming from both the Pacific and the Atlantic. 
There should be widespread negative teens and isolated negative 20s F over the Arctic Ocean and negative single digits over the peripheral seas this time of year. 
As mentioned, this event is being produced by a combination of "heat domes" of high pressure in some locations and strong storms drawing in warm air from both the Atlantic and Pacific. 
7 am CDT Tuesday. 
7 am CDT Saturday. 
In addition to drawing in warm air into the Arctic, these storms produce significant wave action which batter the edges of the thin sea ice, leading to its quicker demise. 
There's something very spooky about seeing the top of the world so incredibly warm. Single digits above/below zero is nothing up in the interior Arctic. Widespread teens and 20s F to above freezing should NOT be happening at such scales and durations at all. This has been problematic all winter, particularly on the Bering Sea, but will become dramatically worse the next couple of weeks. 
The recent view from Barrow, Alaska. The foreground is "fast ice", thin coastal ice which can form and melt rapidly. All that can be see otherwise is open water. 
The sea  ice sheet within the Bering Sea is collapsing abruptly the past 2-3 years. 
It appears this extreme heat event will not end for at least a couple weeks, extending into early-April. This will likely have significant impacts on sea ice melting, which is just beginning. 
----Meteorologist Nick Humphrey

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