tag:blogger.com,1999:blog-4572286363399496963.post5120113040838082397..comments2024-03-27T04:17:21.221-08:00Comments on Deep Cold: Alaska Weather & Climate: Why Cold Now - Part 2Rickhttp://www.blogger.com/profile/03946704894714514716noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-4572286363399496963.post-55569409365746385502020-03-20T22:43:55.546-08:002020-03-20T22:43:55.546-08:00One last question. Does the Climate Prediction Cen...One last question. Does the Climate Prediction Center that forecast a "warmer" winter for Interior Alaska as I recall have an unfogged rear view mirror? If so what changed? And particularly over the Aleutian Islands and Gulf of Alaska? <br /><br />GaryNL7Yhttps://www.blogger.com/profile/15874712728971005352noreply@blogger.comtag:blogger.com,1999:blog-4572286363399496963.post-6874460907600798432020-03-12T16:49:31.300-08:002020-03-12T16:49:31.300-08:00Here's a readable summary discussing both the ...Here's a readable summary discussing both the tropospheric and stratospheric polar vortices (PV):<br />https://journals.ametsoc.org/doi/pdf/10.1175/BAMS-D-15-00212.1 <br /><br />The authors suggest a strong stratospheric PV event may be due to several factors including: Infra-red cooling at the Poles equalling or exceeding solar heating, and seasonally weak Rossby Wave flow from the troposphere up into the stratosphere supporting that radiative equilibrium and cold air. Also note in my post above this winter's stratosphere>troposphere downward coupling and cooling of the lower atmosphere.<br /><br />My takeaway at least. I'm sure there's more.<br /><br />GaryNL7Yhttps://www.blogger.com/profile/15874712728971005352noreply@blogger.comtag:blogger.com,1999:blog-4572286363399496963.post-54711834110262271892020-03-12T04:02:24.269-08:002020-03-12T04:02:24.269-08:00Thanks for the comments, Gary. Yes, the strong st...Thanks for the comments, Gary. Yes, the strong stratosphere-troposphere coupling by late winter was a very striking aspect. There is a broad literature on stratospheric vortex forcing/disruption mechanisms, so I agree that would be a good line to pursue. And I'll try to identify the regime change you mention... an interesting suggestion.<br />Richard Jameshttps://www.blogger.com/profile/08313902028896263276noreply@blogger.comtag:blogger.com,1999:blog-4572286363399496963.post-54031696217310498572020-03-11T21:24:23.834-08:002020-03-11T21:24:23.834-08:00From Fairbanks it appeared:
Something caused a reg...From Fairbanks it appeared:<br />Something caused a regime change in the Arctic between late Fall and early Winter 2019.<br />The Jetstream circled the Polar Vortex but rarely disturbed the latter. It may have contained and contributed to its longevity.<br />There were at times prolonged strong Stratosphere-Trophosphere coupling events with associated low Polar Cap Heights.<br />Thee were few high altitude clouds observed. It was either clear or snowed then repeated. A shortwave event then back to cold.<br /><br />I wonder if looking at the regime change in latter 2019 might offer some clues? Beyond that.....what contributes to and maintains a strong Polar Vortex?<br /><br />Gary<br /><br />NL7Yhttps://www.blogger.com/profile/15874712728971005352noreply@blogger.com