The case for Invisible Arctic clouds

~Following a long series of particularly unexplainable refraction variations,  one culprit was no less  clear air water vapor and lower altitude ice crystals (specific from various geometric species).  They may not be seen,  but rival long wave feedbacks similar to  clouds physics.

~We give here some recent examples to be found amongst many others

    The first thing in identifying the effects of invisible clear air moisture is to describe what happens when the High Arctic is cloudy:

  March 5, 2018.  We observe the sea ice horizon fading by the arrival of Stratocumulus clouds 4300 feet high eventually covering the sky.   On this day with overcast conditions, precipitable water of the entire air column was a mere 1.44 mm.  In the Arctic,  cloudy conditions may occur with very little precipitable water (pw) .  During winter,  precipitable water  in the High Arctic seldom exceeds 3 mm,  more often  between 1.0 and 2.0 mm during clear sky conditions or not.   Hinting the great possibility of invisible clouds,  with moisture formations giving surface based long wave radiation variations similar to when cloudy.   In the photo above,  the sea ice horizon was 2.3 arc minutes above astronomical horizon before overcast conditions occurred.   It is common to loose the visual sea horizon when the sky is overcast with low clouds,  at times it is measurable.  When able to do so ,  the horizon can be very near the Astronomical Horizon altitude.

       Further examples abound:   January 26 2018 had very low overcast conditions,  pw was 2.10 mm,  on the 24th same month 300 feet stratus near overcast skies had a pw column of 1.18 mm,  on the 12th of January various altitude clouds were part of 1.48 mm pw. On Feb 12, 2018 0.85 mm with alto cumulus dominating overcast.  When mid air winds are not so strong, spontaneous cloud formations can also be seen throughout winter,  sometimes appearing and disappearing within a few hours,   this is not an often quoted meteorological process,  but it can be said that the cloud may revert to invisible or visible mode.

     On many observed occasions,  horizon heights defied logic,  sometimes higher or lower  than would be expected given nearly identical meteorological conditions from one day to the next.  But First Melt 2018 might have exposed  one secret player for all of us to consider.  First Melt is a horizon event marking the return of sea horizon elevation to Astronomical Horizon.  Implying
T*** = Ts,  top of snow (ice) temperature is equal to surface air temperature:

Note the March 14 horizon sky,  it is whitish by local smog,  but the sea ice is at astronomical horizon height.  First Melt came early with surface temperatures below -40 C,   otherwise suggesting dry air, but that may be a bit misleading. It was the coldest day of winter with tropopause height below 500 mb!  Of course the stratosphere above the troposphere is almost always devoid of moisture, as happening here,   the entire 0.66 mm precipitable column was found compressed between surface and 590 mb:

     Mixing Ratio (gr/kg) vs altitude in meters.  March 15 00 UTC  Radiosonde from station 71924, South Cornwallis Island Nunavut Canada.    An extraordinary moisture profile.

    First Melt is an event caused by top of sea ice temperature equal to surface air,  for March 14 event to have happened,  it was necessary for thin sea ice to be present,  because thin sea ice has more potential  heat to compensate for extreme cold air,   very frozen air  cooling top of sea ice tends to be cancelled by the heat of the ocean,  but on this afternoon,   the sun's short wave radiation stopped sea ice top from cooling,  in fact was warming it along with the air at its interface.

    With much thicker sea ice the equation of winter would be more often: T*** < Ts,  causing  strong inversions since thicker sea ice insulates the warming from -1.8 C sea water. 

      If it was only thin ice causing  First Melt to be early,   identical sun rays at equal or coming from higher point in the sky would continue giving a daily drop to Astronomical Horizon after local apparent noon for days to come,   that was not so,  next  clear days had it slightly or much higher horizons:

March 16 2918,  with 11.5 degrees sun elevation as opposed to 11.4 for the same spot 2 days ago,  gave a dramatically higher horizon elevation,  nearly 1 arc minutes higher.  Same sun elevation,  same sea ice with identical snow with no major weather event in between,  however  different horizon height??  You have noticed correctly a bluer sky  captured with identical equipment as for March 14 picture, there was a lesser local upper inversion preventing smoke from scattering,    it was also 6 degrees C warmer.    March 14 picture had highly compacted moisture but very little  as opposed to March 16:

   March 16 2018 tropopause was much higher than March 14,  with moisture more scattered throughout its upper air profile till the tropopause.  This suggests  double the precipitable water  has had an effect on the altitude of the sea ice horizon,  which it possibly had,  the air on First Melt day was very dry,  this allowed more Short Wave through,  called solar forcing . 

   The over all impact of clear air moisture ,  its contribution to long wave radiation deflections may be small to important,   however it can be measured even while not observing refraction effects. Top of snow temperature layer minus surface temperatures may dramatically vary day to day without any clouds.  While precluding windy days,  there are several examples of unexplainable variations of refraction and snow temperatures during clear air conditions,  only plausible with the presence of clouds.

     Invisible clouds were first suspected by strange refraction observation variations eventually confirmed by correct top of snow and surface air observations.  An overcast with low clouds day can have top of snow temperatures always very close or equal to surface air temperatures.  When not cloudy,  with dominant  clear skies,  top snow layer may be persistently equal to Ts  as well,  even during the presence of the sun going up and down.   Refraction observations obtained similar horizon heights  as with extensive cloud coverage or with clear skies,  in both instances an indication of a long wave feedback system,  sometimes with bounce back points easily conclusive,  sometimes not.  If all air moisture wasn't invisible I would write about their geometry.  At any rate,  we do have many examples of observed days with T***=Ts with very few clouds or none at all,

       Jan 13  2018 a clear day in darkness,  following a cloudy one,  similar T*** and Ts on all readings , pw was 3.26 mm.    Jan 17,  2.70 mm .    Apparent clear air moisture preceding coming of a cyclone system was detected March 11 with a 2.51 mm pw.  February 20,   1.79 mm.

      Some observations were rather confusing to analyze:  March 12 1.43 mm.   Jan 15 in darkness 1.37  and March 15  with 1.18 mm .....  All these observations suggest not seen moisture likely  affecting the climate in the longer term.  wd March 21,2018

High Arctic sea ice First Melt 2018 earliest in short monitoring history

~First melt 2018 predicts a coming great sea ice melt with a high degree of confidence..  

~Very latest discoveries unveils largely invisible moisture capable of bouncing back Long Wave Radiation much like clouds.  

~This affects sea ice horizon readings without affecting the theory behind "First Melts" observations. 

    
When the sea ice horizon comes back down to astronomical horizon elevation after always being above that altitude throughout the entire High Arctic winter, this event is called "First Melt". When accretion stops, bottom sea ice may be fragile and or melt. This happens when the temperature top of sea ice/snow is equal to surface air. During the dark season , ice accretes when interface sea water looses heat towards space, this heat loss stops when temperature of top sea ice/snow is same as surface air some weeks after long night sunrise with sun high enough to warm up the top of ice sheet. Astronomical horizon is reached as long as the sun warms the top of ice, and then when daily sun lowers towards setting, sea ice horizon rises. The degree of horizon elevation fluctuations depends on sea ice thickness and how porous the Arctic atmosphere to short and long wave radiation. Overcast skies can theoretically create first melt conditions, but this was hardly observed. First Melts usually occur a few hours after local apparent noon when sunny with rays well above 5 degrees elevation. With thinner sea ice, the core minima temperature of sea ice column is not as strong and expansive as with very thick multiyear sea ice, the sun can warm top of sea ice quicker, likewise, and this is a very latest discovery, if the atmosphere is very porous to long and short wave radiation, the First Melt would tend to arrive later than usual, if the atmosphere blocks and bounces back all radiations, First Melts may come earlier, because it is not really a matter of temperature, but a matter of no temperature difference between surface air and top of sea ice. In simpler terms, a long Arctic night with a long term persistent more saturated or moist atmosphere is not good for sea ice accretion, sea ice would become thinner under these conditions with less radiation having escaped towards space.

First Melts in brief history:

2017 April 25,   In earliest Chronology:   2012  ~ 2012 PIOMAS peak to peak max. volume loss  

2016 March 18,                                           2016      2010                                                 

2015 March 26,                                           2010      2016

2014 April 10,                                             2013       2011           

2013 March 23,                                           2015       2015

2012 March 17,                                           2014       2013

2011 April 15,                                              2011       2017

2010 March 19.                                           2017       2014

        March 2016 was corrected upon verification of data, was off by 0.2 arc minutes. 2011 was the only outlier on otherwise largely predictive powers of First Melt data with respect to conditions of not only sea ice, currently near or at record thinness, but also atmospheric conditions, in particular how persistently moist or how dry the Arctic long night atmosphere was. This explains 2011 as it was very likely a drier long night, this has something to do with circulation patterns, unlike 2018 where we have had a continuous onslaught of Cyclonic intrusions from both the North Pacific and Atlantic. Furthermore 2011 Arctic winter occurred during a very deep La-Nina which was ideal for lesser clouds. 2011 equally had record number of very damaging tornadoes further South, along with very cold stratosphere, on "steroids" as I wrote.


     2018 First Melt happened March 14, the earliest on record since monitoring has started. Throughout the long night the sea ice horizon of the Central North West passage tended to be low. Not always, but more often low than higher. This was an indication of a largely pervasive moist atmosphere, which is an anti-accretion process during the dark season. The two geophysical processes go hand and hand, thinner sea ice is the product of a warmer more moist atmosphere during winter, snow adds on to this process, more snowfall replaces ice thickness, because a thick snow layer is fairly good insulation. The current over all sea ice thickness of the Arctic may be much thinner for a very large area of the Arctic Ocean given that South Cornwallis Island is a representative area of sea ice conditions extending well beyond the Canadian Arctic Archipelago, mainly because the stated prolonged moist atmosphere came mainly from the North Atlantic by way of the North Pole. WD March 17,2018

Back towards El-Nino; no post 1998 La-Nina rebound yet...

~High Arctic skies are recently strangely cloudier.
~A few days ago a clearer evening had telltale ominous high black cloud streaks up to 10 degrees above the horizon,  they only appear when trending El-Nino or at extreme El-Nino peak temperatures. 
~It seems not believable because we never went deep La-Nina like post 1998 immediate years

      BOM Australia demonstrates a clear ENSO trend towards El-Nino:

As we recall 2 years after 1998 super El-Nino the world SST's looked like :

Deep cold La-Nina was well in place 2 years following 1998 super El-Nino , very unlike  2016's post SST action:

    NOAA depiction of preceding 2 weeks SST's  reveal a significant warming about the Galapagos Islands.  Which if continuing would preclude a High Arctic big blue sky spring event.  Increasing cloudiness should happen if trending towards El-Nino continues.  
This has significant impact for the summer sea ice melt season which would delay earlier spring onset of melt ponds.  WD March 2, 2018

Clear air moisture species; some let through Long Wave Radiation, some bounce it back

 ~A recent steady continuous influx of Cyclonic moist air originating from the  North Atlantic steered counterclockwise around Northern Greenland often did not show up as clouds
~Upper Air remnants of moist air mixed with smaller deep cold CAA vortice usually hanging about 67 North 85 West for weeks.
~This vortice was like a "black hole" steering all atmospheric matter around it.
~Many were observed as having clear air exotic moisture events ,  which despite apparently no clouds,  transformed the horizon as if there were clouds.
~This meant Long Wave Radiation did not freely escape towards space and gave very low sea ice horizons.

   South Cornwallis Island,  it was -34 C on January 21 2018,  with apparent clear skies,  further to the South it was much colder.  This very low sea ice horizon is counterintuitive,  does not respect the concept of clear air Long Wave radiation escaping to space.   Unless the upper Air profile has Long Wave reflecting moisture rich layers.  Precipitable water was a mere 2.7 mm.  At this horizon altitude,  there is much less sea ice accretion than when top of sea ice/snow is super cold,  when top is extremely cold the horizon can rise up to 3 times higher, in fact measured sea ice thickness stalled for weeks along with sighting such low horizons.
The horizon elevations in all quadrants were consistently lower for most of the long night of 2017-18.

  Jan 22 00 UTC 2018 71924 Upper Air relative Humidity profile vs Altitude,  it wasn't a dry profile despite 2.7 mm total precipitable.  Some of the moisture layers had exotic Long Wave properties
which reflected back Long wave radiation as if there were clouds.

    University of Wyoming map Jan 22 2018 00 UTC,   total precipitable looking throughout the Arctic ,  there was not much water in the atmosphere basically everywhere,  but water can take many forms,  either from super cooled to many different species of ice crystals.   In the Canadian Arctic Archipelago, some had "cloud like" properties,  despite not being seen.  WD February 27,2018

Big Lead Spring Break event 3 months early

~The legendary  "Big Lead" exists,  it shows up in various ways depending of date of year
~This February 26 2018 showing comes with lateral and perpendicular fractures with micro-fractures
~ This usually was an early June event....

Look very carefully North of Central Canadian Arctic Archipelago.  To the left there will be a small cyclone moving East,  it will bring out the Big Lead.  A deeper look reveals a chaotic well battered sea ice prior to these lead creations.  Right after or during the big coastal movement was like a tremor causing many lead fractures to bring out heat signatures,  open water everywhere:  

This kind of break up action was a late May or early June event.  This February 26 2018 badly broken up sea ice is a qualifier of current state of Arctic Ocean ice,  looser, more fluid,  a special feature of a not so long ago beginning of summer.   However, Big Leads showed in February's not so distant past,  but had a very typical look of a single lead parallel to the Canadian Arctic Archipelago Coast without the fractures,   it opened and appeared to shut quickly,  because air temperatures were very cold (-45 to -50C) ,  open water froze rapidly,  drifting snow swiftly covered the fresh ice,  tides also closed the gaps.  It typically visually disappeared in 2 days.  WD February 26, 2018

A different Arctic in 30 years, very cold atmospheric region moved South where land dominates

~Very thick sea ice had one major  impact,  it centered the Cold Temperature North Pole (CTNP) more towards the North Pole.

~We look back and remember a different long night climate.  

     Moving North towards the North Pole at longitude 90 degrees West ,  this February 10 1988 infra red satellite picture demonstrates great white,  meaning really deep cold weather spanning huge distances: 

The coldest area was Northern Greenland and Ellesmere,  where very thick sea ice was abundant.  

Extreme North Pole trekkers  starting from Northern Ellesmere experienced the frequent -45 to -50 C welcoming temperatures.

30 years later:

The great white area is much smaller with this CMC animation sequence,  very well to the South of Ellesmere Island strangely not only warmer for this day February 20 2018,  but for weeks!

The consequence of this much smaller cold zone shifts weather patterns for a great region of the world.  Especially repeatedly directing warm Cyclones hugging Greenland's East Coast towards the North Pole then back towards the Canadian Arctic Archipelago.  Making said Ellesmere way warmer than Nunavut and NWT Canada mainlands.   These are different weather days.  When coldest air is from the South of the High Arctic:

 Looking back 30 years ago,  february 8 1988,  the coldest air was over the Arctic Ocean, when  freezing -45 C's were common until mid March. Today the Arctic Ocean surface air is radically warmer,  driven by smaller cold air vortices on both North American and Eurasian continents which move continuous ocean warmed cyclones towards the North Pole. The consequences of this results in what is called Arctic warming Amplification. 

   NOAA Map room 30 day surface anomaly January 20 to February 18 2018 clearly depicts a great warming of the Arctic Ocean surface air, going in tandem with thinner sea ice.  
1988 NOAA daily composites with 30 day same period as above was much more colder on the anomaly side of temperatures over the Arctic Ocean in particular.  WD Feb 21, 2018

Very weak tropospheric polar vortex brings up cyclonic heat

~Smaller, weaker elongated Arctic Polar Vortex
~Coldest Vortices weakest compared to last 4 years

Based on CMC January 25 0000 UTC 700 mb data measurements,  because it is closest to 600 mb,  the actual average temperature of the entire troposphere,  along with below 500 mb height,   implicating lower atmospheric circulations.     We see two important Cyclones typically going Northeastwards,  the furtherest North one is following a " northern warming" path,  heavily influencing the temperature of the Arctic Ocean.  The elongated aspect of the North American vortex is a sign of winter weakness, readily identified by its temperatures, once called  by weather TV presenters the "Polar  Vortex"

was really a vortice(s) within the Polar Vortex having temperatures well below -30 C forming at a Southward location.  As we can see here ,  none to be found in North America but for a faint one North of Alaska,  which has finally got a bit colder.

   The current North Pacific situation is very interesting,  absent a Greenlandic barrier,  a significant Cyclone crashes Westwards right into the coldest vortice,  yesterday North Japan had 700 mb temperatures -33 C,   these numbers warm substantially at present as the Siberian coldest atmosphere will relinquish this ranking to Northern Canada's CAA very soon (**Mongolia and North central China was equally very cold,  but outside the range of multi year study with same map grid).    This has been mid-winter  2017-18 outlook,  an oscillation between coldest atmospheres between NE Siberia and Canadian Central Arctic Archipelago , one cools while the other warms.  Looking back to 2014,  there has not been a warmer atmosphere than now.  A key describer is the lack of -30 C vortices within the Arctic Polar Vortex.  This will likely continue and result in again record warm temperatures for the Arctic,  despite strong El-Nino just past. 

**Mongolia and high elevated regions ( about 1 kilometers or more ASL)  have incomparable pressure temperatures,   while I aim to read at 600 mb level,  but only do 700 because there is not many 600 mb charts produced,  the Equivalent Mongolian pressure level to 600 mb is 450 mb,  because at that pressure height lies close to  the average temperature of this thinner troposphere.  It is best to stick to charts from Polar stations lower than about 600 meters altitude.  Jan 30 **

WD January 25-26 (second map changed on 26) 2018

Vanishing Polar Vortices

January 20 2017,  700 mb temperature measurements captured a cold mid sized Arctic Polar Vortex with 3 vortices,  the larger yellow line expanse is -20 C isotherm,  within are significant colder vortices having temperatures lesser than -30 C,  at their center are CTNP's (Cold Temperature North Poles),  all with winds turning counter clockwise around them.    We note Alaska and near North of URALS Russia, having one,  very unlike 2018 winter to date.

January 16 2018,  A very different scene indeed,  Urals and Alaska were much warmer, not only on same yearly days  but throughout the winter to date.  We notice the Russian Vortice CTNP being coldest in the World,  but it was not always so.  It has been rebuilt from a devastating North Pacific Cyclonic merge,  at one time there was no significant vortex on that side,  a few weeks back with Upper Air temperatures exceedingly warmer.   These are the times when vortices regularly disappear in the Arctic from warm Cyclonic Northward incursions,  particularly driven North by smaller  in size vortices  .  

Notice the Canadian side Vortice in the process of vanishing,  Ellesmere Island being warmer than Disko Island Greenland,  quite astounding.   

   

  January 17 2018,  we note the Russian vortice stable and cooling a bit.  But the Canadian Arctic Archipelago vortice receiving a final literal blow of warm air coming from the North!   An amazing feature,  this of course changes weather patterns throughout North America.  WD January 21,2018

T***<=Ts duplicated in a Southern location with special instrumentation

Congratulations and salutations to:

C. L. Pérez Díaz , T. Lakhankar , P. Romanov , J. Muñoz , R. Khanbilvardi, and Y. Yu

who wrote and published:

Near–surface air temperature and snowskin temperature comparison fromCREST-SAFE station data with MODISland surface temperature data

~Although not looking for a Skin snow temperature (T***) vs Surface air  (Ts) relation, a very significant paper measured it with great precision using different instrumentation.  At Caribou, Maine USA (46◦ 520 5900 N, 68◦ 010 0700 W)

~ Instruments  : "An Apogee Infrared Radiometer is used to measure snow skin temperature directly by converting thermal energy radiated from the surface in its field-of-view (FOV) to an electrical signal with a response time of less than 1 s (Muñoz, 2014). This process is automated at every 3 min to an accuracy of 0.2 ◦C. The air temperature is measured directly by a Vaisala Temperature/RH Probe through an automated process; also at a 3 min sampling interval with the same accuracy"

      The results from this effort are very important to study:

Caribou Station equipment extraordinary capacity to measure snow surface skin temperatures with accuracy even with the presence of the sun probably offers the proper way to re-equip  mass balance sea ice buoys. 

As we can see,  T***<=Ts ,  snow skin temperature seems indeed always colder than Surface air temperatures even with hourly measurements.  This has been observed optically either over land thoroughly covered by snow or especially at the Arctic Ocean horizon.  The effects of winds, tend to reduce near refraction as well.,  but not always, this has been a subject of great interest.   

Here are a few very important observations and conclusions from the authors (in Italics):

~"Results indicate that near-surface air temperature correlates better than snow skin temperature with MODIS LST data"

   I have found that so, in particular if NOAA daily climate composites uses MODIS as their data source.  I established that we can detect a satellite error by using said simple formula T***<=Ts.
 
~"This leads to the suspicion that maybe ground-measured LSTs in high-latitude regions covered in  snow might not display congruent behavior with satellite readings. Because if the snow temperature satellite readings are far from the real values, this can lead to confusion when trying to predict the occurrence of avalanches or spring floods."

    Suspicion confirmed,  particularly in the Arctic,  this was frequently observed while comparing NOAA daily composites,  while they had skin temperature option available,  a significant problem here, recognized by the authors,  are irregular surface features,  either not covered by snow completely or affected by high vegetation,  trees for instance.

~Near-surface air temperature tends to affect the snow skin temperature directly, although the latter’s fluctuations are not as drastic (Walsh et al., 1985). The record shows that the winter of 2013 was the coldest of the two (hourly lows of −26 and −36 ◦C in late January for T -air and T -skin, respectively). However, it cannot be ruled out that it is possible for the near surface air temperature to be colder than the snow skin temperature at particular times throughout some winter days, but not common on a daily average basis."

    While using much simpler instrumentation and a different technique altogether,  the latter assumption:  "However, it cannot be ruled out that it is possible for the near surface air temperature to be colder than the snow skin temperature at particular times throughout some winter days",
has never been measured with more primitive method, unless the ground surface has a mix configuration of snow and exposed land,  similar to sea ice mix with open water,  which gives a different horizon height."Near-surface air temperature tends to affect the snow skin temperature directly, although the latter’s fluctuations are not as drastic" ,  this has not been observed here in the High Arctic, surface temperatures  and skin temperatures vary in tandem almost if not instantly, sometimes skin temperatures vary independently while surface temperatures do not and vice-versa.  If the authors rather implied that very near the skin of snow air temperatures may be colder than top of snow,  I do not believe so,  but the temperatures can be equal.

Self published related articles:

http://eh2r.blogspot.ca/2017/12/ts-ts-is-probably-greatest-winter.html
http://eh2r.blogspot.ca/2017/03/consequential-application-of-first-rule.html
http://eh2r.blogspot.ca/2017/03/first-rule-of-sea-ice-horizon.html
http://eh2r.blogspot.ca/2017/02/summer-greater-cloudiness-thermal-flux.html
http://eh2r.blogspot.ca/2016/06/the-models-may-be-calculating-sea-ice.html
http://eh2r.blogspot.com/2016/05/optically-unlikely-not-possible-remote.html
http://eh2r.blogspot.com/2016/05/remote-sensing-vs-refraction-prime-sea.html
http://eh2r.blogspot.com/2016/04/sea-ice-refraction-prime-rule-top-of_28.html
http://eh2r.blogspot.com/2016/04/sea-ice-refraction-prime-rule-top-of_28.html
http://eh2r.blogspot.com/2015/05/dedicated-sea-ice-model-proofing.html
http://eh2r.blogspot.com/2014/04/sea-ice-thermal-balance-appears-to-be.html
http://eh2r.blogspot.ca/2014/06/from-optical-based-hypothesis-to-reality.html
http://eh2r.blogspot.com/2014/06/hrpt-skin-temperature-muddle.html
http://eh2r.blogspot.com/2013/05/sea-ice-phase-change-from-underside.html
http://eh2r.blogspot.com/2013/04/data-gathered-from-optical-refraction.html
WD January 9, 2018

Direct Causal link between ENSO index and Snow extent version 2017-2018

~ Winter Northern Hemisphere Cloud seed theory is :  During El-Nino or especially trending El-Nino more snow,   During La-Nina or especially trending La-Nina less snow

~ It is ecstatic to discover how small this planet is. 


  Proof you ask?

None better than show the facts:

  We note this table from most expansive break down on current ENSO expose (must read here),
look at 2016 brief continuation of El-Nino especially during winter.  Then a downturn to La-Nina from June onwards with a pause in trending during winter 2016-17,  which had significant implications in many parts of the world, then back to trending La-Nina end of 2017.  It means that the trending part is a or the most important aspect.  ENSO reached LA-Nina during the summer of 2016 (when only there is a very small snow signal possible) , however spring 2017 had small upward warming,  which meant more clouds,  which in retrospect affected the entire spring summer season.  And now perhaps the real La-Nina backlash from strong 2014-2016 El-Nino will really show up. 


    So basically if we use the said theory,  there would be more snow in 2016-17 than 2017-18,  lets look

Beginning of winter 2016-17 in light green had indeed  more snow on the ground,   2017-2018 less .   I believe the same can be said with previous winters,  except this graph (taken here) etchings are hard to distinguish.  2011-2012 appears to be lowest which makes sense.  Note the breaking to less snow extent trend starting November 2017 mimicked identically with ONI cooling in table seen just above.  Finally, late winter 2015-16 (I colored matched the outlying lone lowest snow extent in March) had very significant drop in extent , from very high to lowest, exactly when 14-16 El-Nino was ending and substantially trending La-Nina .  WD January 4 2018.