Spring 2021 switchover , transpolar drift staller

 ~Most likely occurring today.

~But not after a great sustained Arctic Basin Gyre did its thing.

 A typically strong Arctic transpolar stream  is pushing out sea ice in great volumes,  but the results are not quite showing since North Atlantic melting has begun.  ITP map

May 30 polar View  SAR shows the exit of old sea (right) pushed by thinner sea ice (top left) which will settle most likely North of Greenland soon,  and there will be great open water  there.  

   It will settle because: 

     CMC prog,  18 UTC may 29, followed by 00-06-12-18 UTC May 31.  Look in particular for the High over Northern Quebec and Atlantic, plus the Low pressure system NW of the Canadian Arctic Archipelago,   this Low already stubbornly present, will persist to affect the sea ice current in favor of saving the sea ice from landing in warm Atlantic waters.  But all the ice dumped to Fram Strait , East of Greenland will melt,  its sort of deja vu dynamics going back a few recent years.  The 2nd smallest minima in history, last September,  gave a lot of new sea ice, melting in place thinner sea ice depends on clear skies, which will happen pretty much everywhere outside of a hovering Low pressure system.

But if 24 hour sunny,  with cleanest air in decades,  which explains the current melting tardiness, melting will be very swift.  WD May 30, 2021

Summer Threshold switchover, when High's become warm and Low's are sustained by cooler air

 ~It is just about to happen,   after long sojourning Arctic Basin High pressure system  

~Impacts sea ice survival in a big way

    The reasons why cyclones persist more in cooler summer weather are obvious,  they cast a shade from the sun.  In the Arctic it is a bit more complex,  sea ice helps create clouds as well,  more of it causes a cloudier Polar summer. Moist air hitting an ice pack easily fogs up,  fog is a cloud touching the surface.   Onto itself summer sea ice and cyclones are a pair,  so it is not surprising that summer Lows tend to survive longer above ice. But there is a time,  such as now,  when cold Highs and Lows may subsist simultaneously:

  3 CMC surface progs, 23 May 00 UTC,  23/06 and 23/12 UTC +extra 700 mb 23/12 UTC.  All showing a less imposing Arctic Gyre High,  apparently moving towards the Canadian Arctic Archipelago where it will eventually be just South of it,  and a 1008 mb Low over the Arctic Ocean Gyre.   Where it will stymie the sea ice exodus towards Fram Strait,  just Northeast of Greenland.   The 700 mb chart portrays this High and Low as having about the same temperature,  this anticyclone will warm a lot,  because it is allows sunrays through,  opposite to the Low, basking in cold, sustained by sea ice,  cloudy weather.  The split in behaviors is temporal in nature and will revert back opposite coming September.  Clouds are essentially all there is stopping a massive catastrophic sea ice melt.  But this is a "frustrated" but nevertheless end of La-Nina weather cycle,  meaning over all lesser clouds and especially warmer High's significantly warmer by lesser pollution at end of Covid pandemic.   WD May 23, 2021

A much warmed and disorganized Polar Vortex created a steady deeper cooling at its center.

~Stable warming of the Polar Vortex is seldom uniform in shape or temperatures.  

~This warming can cause a sudden cooling zone anywhere with very long exposures to the frozen ground and of course by prolonged cloudless air

~Recently we have had a very neat example.  

           Early may 2012 Arctic weather was incredibly warm,  this warming has not stopped,  it kept shrinking  a mangled Arctic Polar Vortex,  but suddenly 1 week later ,  under an even warmer rising sun,  what appears to be impossible occurred:

A small deep cooling area appears near the Pole May 10 (still with a low sun),  it moved over the Canadian Arctic Archipelago where the air was clear,  notice its temperature colder than about 2 weeks prior  (May14) ,  although much smaller, it is strikingly keeping cool despite the P.V. even more dismembered and severely encroached by warmer air all around its perimeter.    What happened is a classic Geophysical phenomena, under certain conditions atmospheric temperatures may drop if  the weather is right,  despite the rapidly approaching summer, despite over all abnormal warming.

This feature can be observed at any time of the P.V. existence.  For instance,  the Northern US can

be coldest place of winter to date more than anywhere else in the Northern Hemisphere.  Notice I use use 600 mb temperature because it is the closest pressure level representing the temperature of the entire troposphere.  500 millibars is more representative of the entire atmosphere, on occasions the stratosphere can be unusually warm or cold,  and can distort tropospheric tendencies if judged by 500 mb maps. WD May 16, 2021 

Arctic 2021 almost just as warm as spring 2016??

 ~However spring 2016 was part of the warmest El-Nino in history

~While spring 2021 is part of the coldest La-Nina since

There is something out of the ordinary coming about:

NOAA ENSO Table,  look carefully at 2015-16  ,  it was really the winter of 15-16 which was very warm,  likewise EH2r vertical sun disks of Spring 2016 were amazingly expanded, in fact all time record number expanded.  Followed,  not surprisingly by 2015,  2010,  all El-nino winters. Climate wise,  the Arctic temperatures zoomed up in 2016,  the gold standard warmest since 1998.   

As a useful weighted temperature of the entire Troposphere comparison,  2016  May 3 date ,  can be compared with others,  averaging out a week or or month would blur the image so much,  it would be difficult to judge the extent of warming.  Any ways,  2012 was end of a very long La-Nina starting in summer 2010. Hence we see a marked ENSO footprint.  The Polar Vortex was of a different nature in 2012,  consolidated, less broken,  as if something more frozen just happened....  Of course 2012 is the year when Arctic sea ice minima was lowest to this date.  

2016 vs 19,  both springs had a winter El-Nino,,  both had broken May 3 P.V..

Of which its internal vortices unleashed their own regional climates.  

A neutral look,  Sprig 2020 came after a neutral ENSO period,  the Polar Vortex was more reformed,  much colder than 2016.  But all is not well, the broken up aspect of the P.V..  perimeter persists.  Since after 2016,  spring time vertical sun disk diameters reflected the consolidated coldest vortice hanging about the Canadian Arctic Archipelago.   

Very strange,  2021 May 3,  quite similar to 2016,  in warmed temperatures and configuration.  Yet

as the ENSO table demonstrates,  the ENSO's are polar opposites,  16 followed the back end of El-Nino and 21 back end La-Nina.  A significant  Canadian Archipelago vortice is still important in 21,  but not as strong as previous years since 2016.  While comparing with 2012,   with very similar ENSO,  2021 is warmer than 12,  refigured like 16,  as if current La-Nina had no effect on the Arctic system.  The only reason this can happen, warmer Oceans ultimately affecting sea ice,   if thinner,  the heat emanating from a huge area would erase the Nina effects.  The warmer Northern Oceans had something to do with tis as well.  WD May 9, 2021

EH2r annual spring summer projections, in greater details, massive heat wave foreseen

~Simply extraordinary systematic Arctic surface air warming, caused newly discovered optical phenomena

~Vertical sun disks in the middle of the pack,  analyzing a much weakened out of normal position Cold Temperature North Pole

~Extra clear air,  confirming a depolluted Arctic atmosphere and a quiescent La-Nina  unable to compensate for historically warmest 2016 El-Nino 

    Since 2016,  the year with the warmest El-Nino in history,  everything was changed further, culminating to Nothing:

     No streaks,  pure molecular air,  a sure sign of de-pollution and especially La-Nina,  no evidence of cloud seeding high clouds,  nothing again and again:

  5 days later April 20 2021,  a totally clear high altitude sky,  sure sign there was or  is a raging La-Nina,  but look at the ground,  with a near record snow cover.  It was cloudy of course, much cloudier than a usual La-Nina spring,  but this snow comes from another sea surface, almost inclusively from  the North Pacific:

Impressive North Pacific high temperature blob anomaly,  currently survives the strongest La-Nina since 2016.  The main difference between a North Pacific warm SST and El-Nino  are the clouds, the Tropical Cumulonimbus are incomparable in height and duration,  they fuel the lower stratosphere with cloud seeds,  which go all over the world.  However, a North Pacific cyclone system has considerable moisture,  which during especially during Arctic fall-winter-spring,  turns to snow.   

   Given that I estimate a very much diminished Polar Vortex (P.V.),  despite La-Nina,  the course of things can be a bit strange.  North Americas main moisture source will come from the Northwest for the earlier part of summer.  Leaving the greater portion of the continent only changeable by synoptic weather,  no longer in the grip of the P.V. sphere of influence.  

Vertical Sun disks; what is the score?

     The vertical sun diameter is a giant thermometer,  taken at the right elevation ,  it purely reveals the temperature of the entire atmosphere.  Since 2016,  another shocking turn occurred,  the disks shrank

despite much warmed world temperatures.  That is because the center of the Polar Vortex,  at its heart, is the Cold Temperature North Pole (CTNP).  since 2016,  the spring CTNP remained steadier over  the Arctic archipelago,  as opposed to the past when it was further South.  The pre 2016 CTNP was found mainly to the South of the Canadian Archipelago,  with a slow move Northwards,  culminating at Northern Ellesmere Island by mid spring,  vertical sun disk dimensions traditionally reflected this movement.  With disks usually bigger in late winter,  then shrinking as the sun rose,  because I was eventually measuring the CTNP from within.  It was not unusual for late spring measurements to have the smallest vertical sun disks.  All this changed after 2016, when  I strangely measured smaller disk diameters for a greater portion of time,  almost all the way to spring end. This made the average vertical sun disk measurements at all time lows since 2001.  In effect skewing its predictive powers,  which made it easy to predict the year end Global Temperature results.  

     Now I keep in mind the location of the CTNP,  which this season was mainly to the North, or at various apparently random locations,  a sure sign that the Vortex has left or has become severely weakened and or shrunken.  With this in mind here are the results:

                                                              ranking,    year,    #1 average maximas* 

*Of 12 decimal levels,  from -1 degrees  to 10 degrees astronomical elevation

      2021 has jumped above the last few years bottom trending to mid pack,  10th place, with 6 average decimal elevations being at all time maximum.  From more than 420 measurements,  taken not often from the CTNP center.   Sun disk  ENSO projection  has been completely muddled by the North Pacific blob sst,  although there is still a correlation,   the measurements of this seasons sun disk coincide with the last phases of a modest La-Nina lasting 7 months,  as long and and in a similar period to 2017-18,  the difference being the observation position mostly away from the Polar Vortex center.  A greater number of sun disk diameter expansions was expected because of very warm surface temperatures,  but the Upper Air still was more normally cold. 

Global Temperatures

        Past measurements of sun diameters were sufficient to predict the annual average temperature of the Northern Hemisphere, but the continuous climatic repositioning to the CTNP makes it more difficult to do so.  But the frequent repositions onto itself is a predictor.  As posited on previous general description article,  the P.V. has been consistently way North its usual locations.  There is no way to have winter reformed in the middle of May.  Therefore this high latitude CTNP in late spring means only one thing,  extremely warm temperatures for most of North America,  with rain for Alaskan coast (seasonal temperatures).  

   Arctic Sea Ice 

               There was another astounding event coinciding with the warmer surface  temperatures,  April 2021 will be on top of the list for the warmest April in Canadian Arctic  history.  At present, Arctic sea ice thickness is locally very thin (middle of Canadian Arctic archipelago), likely all time thinnest.  Therefore,  it is easy to surmise, an early collapse and total melt devastation of sea ice,  but not so fast,  North Pacific moisture will bring more rain to the Arctic and of course greater cloudiness.  The question is whether rain can do in sea ice as fast as the very hot sun?  Is a good one,  we shall see.  But I think the NE passage will still open before the NW by a few days.    Over the Arctic basin,  its again a question of clouds,  this time with less rain,  so I predict (as a measure to see if I understand the geophysics) 2021 sea ice minima slightly smaller than 2012.

     Another fact to keep in mind is top of sea ice (implies snow layer as well) ,  never warmed to same temperature as surface air until April 30 (the latest since observations began in 2010).  This can be optically seen,  if the surface air is always warmer than top of sea ice,  the "first melt"  observation can never be made.  First melt is optically   determined when the top of sea ice temperature is the same as the air immediately adjoining.    Every other year had thicker  or much thicker sea ice.  This late f.m. date is understandable considering the current greater snow insulation cover.  It stops the further warming of more exposed top of sea ice.    Thus extreme snow cover will again tend to complicate prediction models. 

March 21 2012 First melt (left),  while a bit later sea ice horizon rises.  The earlier the first melt the worse the coming melting season,  it was once thought,  but now extreme snow cover implies the very opposite but with the same devastating summer melt.  

  With thicker sea ice , and colder (note the April 11  -31.2 C)  clear weather,  it was possible to reach "first melt" elevation level on April 15 (right ) .  When this occurs there is a thermal balance between top of sea ice and the air right above,  the sea ice horizon becomes the astronomical horizon.  

     In summary ,  end of spring and summer 2021 will be hot,  because the Polar Vortex lost its cold air grandeur. The Global circulation will tend to be stagnant,  favoring weather moved by a much lesser temperature differential,  with no significant Polar driven circulation movement until October.  WD May 2, 2021