With 2017 ice extent estimates complete we can look at the year in perspective.  Above is a graph showing the annual average extents since 2007, comparing MASIE and SII (v3.0).  Obviously, the trend in MASIE could not be flatter, while SII shows a decline.  The first five years the two indices were nearly the same, and since then SII shows less ice, about 260k km2 each year.  Note also how small is the variance year over year: Standard deviation is +/- 260k km2, or about 2.5% of the average annual extent.  This holds for both indices.  Note also a pattern of three higher years followed by two lower years.

A previous post Sea Ice Index Updates to v.3.0 reported on the newest SII version, and we can see how it compares with MASIE over this last year.

The first four months show more diversity, both in the 10 year averages and in 2017 results. From May on MASIE 2017 tracks closely to its average, while SII shows 2017 below its average every month. For those who want to see the numbers a table is provided below.

Units	2007 to 2016	2017	2007 to 2016	2017
M km2	MASIE	MASIE	SII	SII
Jan	13.921	13.503	13.686	13.174
Feb	14.841	14.478	14.553	14.112
Mar	15.053	14.509	14.815	14.273
Apr	14.353	13.941	14.206	13.760
May	12.763	12.838	12.757	12.618
June	10.906	10.975	10.938	10.720
July	8.359	8.383	8.107	7.901
Aug	5.955	6.006	5.657	5.472
Sept	4.663	4.832	4.676	4.797
Oct	6.630	6.804	6.734	6.715
Nov	9.897	9.697	9.718	9.458
Dec	12.235	11.972	12.063	11.752
Annual Ave.	10.798	10.661	10.659	10.396

Some are proclaiming dire warnings about melting ice and imagining various dangerous impacts. Some fluctuations do appear but not very large and somewhat cyclical. Since 2007 it resembles a plateau more than anything else.

Background on MASIE Data Sources

MASIE reports are generated by National Ice Center from the Interactive Multisensor Snow and Ice Mapping System (IMS). From the documentation, the multiple sources feeding IMS are:

Platform(s) AQUA, DMSP, DMSP 5D-3/F17, GOES-10, GOES-11, GOES-13, GOES-9, METEOSAT, MSG, MTSAT-1R, MTSAT-2, NOAA-14, NOAA-15, NOAA-16, NOAA-17, NOAA-18, NOAA-N, RADARSAT-2, SUOMI-NPP, TERRA

Sensor(s): AMSU-A, ATMS, AVHRR, GOES I-M IMAGER, MODIS, MTSAT 1R Imager, MTSAT 2 Imager, MVIRI, SAR, SEVIRI, SSM/I, SSMIS, VIIRS

Summary: IMS Daily Northern Hemisphere Snow and Ice Analysis

The National Oceanic and Atmospheric Administration / National Environmental Satellite, Data, and Information Service (NOAA/NESDIS) has an extensive history of monitoring snow and ice coverage.Accurate monitoring of global snow/ice cover is a key component in the study of climate and global change as well as daily weather forecasting.

The Polar and Geostationary Operational Environmental Satellite programs (POES/GOES) operated by NESDIS provide invaluable visible and infrared spectral data in support of these efforts. Clear-sky imagery from both the POES and the GOES sensors show snow/ice boundaries very well; however, the visible and infrared techniques may suffer from persistent cloud cover near the snowline, making observations difficult (Ramsay, 1995). The microwave products (DMSP and AMSR-E) are unobstructed by clouds and thus can be used as another observational platform in most regions. Synthetic Aperture Radar (SAR) imagery also provides all-weather, near daily capacities to discriminate sea and lake ice. With several other derived snow/ice products of varying accuracy, such as those from NCEP and the NWS NOHRSC, it is highly desirable for analysts to be able to interactively compare and contrast the products so that a more accurate composite map can be produced.

The Satellite Analysis Branch (SAB) of NESDIS first began generating Northern Hemisphere Weekly Snow and Ice Cover analysis charts derived from the visible satellite imagery in November, 1966. The spatial and temporal resolutions of the analysis (190 km and 7 days, respectively) remained unchanged for the product’s 33-year lifespan.

As a result of increasing customer needs and expectations, it was decided that an efficient, interactive workstation application should be constructed which would enable SAB to produce snow/ice analyses at a higher resolution and on a daily basis (~25 km / 1024 x 1024 grid and once per day) using a consolidated array of new as well as existing satellite and surface imagery products. The Daily Northern Hemisphere Snow and Ice Cover chart has been produced since February, 1997 by SAB meteorologists on the IMS.

Another large resolution improvement began in early 2004, when improved technology allowed the SAB to begin creation of a daily ~4 km (6144×6144) grid. At this time, both the ~4 km and ~24 km products are available from NSIDC with a slight delay. Near real-time gridded data is available in ASCII format by request.

In March 2008, the product was migrated from SAB to the National Ice Center (NIC) of NESDIS. The production system and methodology was preserved during the migration. Improved access to DMSP, SAR, and modeled data sources is expected as a short-term from the migration, with longer term plans of twice daily production, GRIB2 output format, a Southern Hemisphere analysis, and an expanded suite of integrated snow and ice variable on horizon.

http://www.natice.noaa.gov/ims/ims_1.html

Footnote

Some people unhappy with the higher amounts of ice extent shown by MASIE continue to claim that Sea Ice Index is the only dataset that can be used. This is false in fact and in logic. Why should anyone accept that the highest quality picture of ice day to day has no shelf life, that one year’s charts can not be compared with another year? Researchers do this, including Walt Meier in charge of Sea Ice Index. That said, I understand his interest in directing people to use his product rather than one he does not control. As I have said before:

MASIE is rigorous, reliable, serves as calibration for satellite products, and continues the long and honorable tradition of naval ice charting using modern technologies. More on this at my post Support MASIE Arctic Ice Dataset

Arctic ice extent grows slowly this time of year since many regions are already covered completely.  In recent days 2017 reached 84% of the maximum last March, but dropped below the 10 year average.  As we can see, most of the action was a dramatic seesaw in Okhotsk Sea, a Siberian basin in the North Pacific.

Mid-December Okhotsk Sea on the left began growing ice steadily to reach half of 2017 March max, then inexplicably lost over 300k km2 of ice in just four days.  Meanwhile, Chukchi (upper right) froze completely, then retreated somewhat.  Bering Sea on the right has been advancing steadily but more slowly than average.

The overall effect in December is shown in the graph below:
Note that 2007 matches the 10 year average, while 2012 is well above.  Lagging behind are 2016, 2017 and SII 2017.  This year’s deficit to average appears in the last 11 days, mostly due to Bering and the Okhotsk year end surprise.
Most of the month combined Bering and Okhotsk (B&O) extents were average, until the inexplicable drop starting day 361. Except for those two seas, the month was unremarkable.
At year end, 2017 NH ice, excluding B&O, is down about 200k km2, or 2% of average.  Below is the analysis of regions on day 365.

Region	2017365	Day 365 Average	2017-Ave.	2007364	2017-2007
(0) Northern_Hemisphere	12628187	13148939	-520752	13049737	-421550
(1) Beaufort_Sea	1070445	1070225	220	1069711	734
(2) Chukchi_Sea	943883	966001	-22118	965971	-22089
(3) East_Siberian_Sea	1087120	1087134	-14	1087120	0
(4) Laptev_Sea	897845	897841	4	897845	0
(5) Kara_Sea	892689	888842	3848	871851	20839
(6) Barents_Sea	331819	448769	-116950	334577	-2758
(7) Greenland_Sea	555757	584649	-28892	666135	-110378
(8) Baffin_Bay_Gulf_of_St._Lawrence	978074	1025197	-47123	1074827	-96753
(9) Canadian_Archipelago	853109	853054	55	852556	553
(10) Hudson_Bay	1260838	1227587	33251	1260856	-19
(11) Central_Arctic	3191526	3207659	-16133	3199726	-8200
(12) Bering_Sea	194350	446066	-251716	373942	-179592
(13) Baltic_Sea	13345	34329	-20984	9972	3374
(14) Sea_of_Okhotsk	336595	387522	-50928	371241	-34646

Most of 2017 deficit is in Bering and Barents, less so in Okhotsk with yesterday’s recovery.  Perhaps the Polar Vortex sent frigid air into the US and Canada and replaced it with warmer southern air, and ice receded as a result.  I have reported on Arctic incursions in a post Arctic Inversions and Intrusions but the speed of the effect on ice (if that is the phenomenon) is still surprising.  We shall see if it persists or not.

Background:  Winter Forecast by Dr. Judah Cohen, Dec. 25

On Christmas Day Dr. Judah Cohen published his updated Arctic Oscillation and Polar Vortex Analysis and Forecast  Excerpts below

As I have been discussing the past two blog posts I continue to believe that this is the most critical period of the winter and will ultimately determine the character of the winter. In my opinion, we have approached a fork in the road and the atmosphere can take two possible paths one is a path where the rest of the winter is relatively mild across the mid-latitudes of the NH and the second is a colder path or solution. The tropospheric polar vortex has been relatively weak for much of the month of December as illustrated by the relatively warm polar cap geopotential heights (PCHs) for the first half of December that then boomeranged off the mid-stratosphere and after a short respite with colder tropospheric PCHs, warmer PCHs in the troposphere are predicted through the end of the month and into early January.

Based on the easterly phase of the Quasi-Biennial Oscillation (QBO) I have been favoring a significant PV disruption most likely in January for much of the fall.  A significant stratospheric PV disruption would then be followed by an extended period of severe winter weather across the mid-latitudes of the NH.  However, I have to admit as of yet there are no signs of this scenario.  There is still time but not much.  However, there is another scenario that could still yield a relatively cold winter and that is one analogous to what happened in the winter of 2013/14 where no significant disruptions of the stratospheric occurred but rather repeated minor disruptions that yielded a cold winter for central and eastern North America. Though at first, I acknowledged this possibility I was hesitant to favor this scenario.  However, the longer the delay in a major disruption of the stratospheric PV the more I favor this scenario.

The Arctic Oscillation (AO) is currently slightly positive and is predicted to trend slowly negative through the end of the week towards neutral. The forecast is for the AO to remain close to neutral next week, likely a sign of uncertainty.

The current positive AO is reflective of mixed pressure/geopotential height anomalies across the Arctic and mostly positive pressure/geopotential height anomalies across the mid-latitudes. The North Atlantic Oscillation (NAO) is also currently slightly positive with weak pressure/geopotential height anomalies across Greenland and Iceland and positive pressure/geopotential height anomalies across the mid-latitudes of the North Atlantic.

A return to Ural ridging/blocking at the turn of the calendar year favors active energy transfer from the troposphere to the stratosphere. Another pulse is predicted to commence this week and peak the first few days of January. The pulse itself is likely related to relaxation of the pattern and mild temperatures across North America. However, the predicted resultant perturbation to the stratospheric polar vortex (PV) especially the building of heights over northwestern North America in my opinion could once again favor the return of cold temperatures across eastern North America later in January.

Ice did not grow this past week on the North Pacific side of the Arctic basin, still I expect the negative ice anomalies in the region to shrink.  Sea ice is below normal in the Barents-Kara Seas as well and with time the greatest negative sea ice anomalies will likely reside in this region.  As I have been writing for much of the fall I do believe that the record low sea ice anomalies in the Chukchi and Bering Seas has focused ridging/blocking in this region.  Though model forecasts do not predict a return of the blocking in the foreseeable future.

Recent research has shown that regional anomalies are important and the sea ice region most highly correlated with the winter AO is the Barents-Kara Seas region where low Arctic sea ice favors a negative winter AO and a cold Eurasia.  Below normal sea ice in this region may be contributing to more active Wave Activity Flux/poleward heat transport predicted in the models that eventually could result in a negative AO.

As we have seen, the Polar Vortex did indeed return to North America, freezing Niagara Falls in the process.

Whichever fork the ice takes, the Polar Bears had a Merry Christmas

 

 

On Christmas Day Dr. Judah Cohen published his updated Arctic Oscillation and Polar Vortex Analysis and Forecast  Excerpts below

As I have been discussing the past two blog posts I continue to believe that this is the most critical period of the winter and will ultimately determine the character of the winter. In my opinion, we have approached a fork in the road and the atmosphere can take two possible paths one is a path where the rest of the winter is relatively mild across the mid-latitudes of the NH and the second is a colder path or solution. The tropospheric polar vortex has been relatively weak for much of the month of December as illustrated by the relatively warm polar cap geopotential heights (PCHs) for the first half of December that then boomeranged off the mid-stratosphere and after a short respite with colder tropospheric PCHs, warmer PCHs in the troposphere are predicted through the end of the month and into early January.

Based on the easterly phase of the Quasi-Biennial Oscillation (QBO) I have been favoring a significant PV disruption most likely in January for much of the fall.  A significant stratospheric PV disruption would then be followed by an extended period of severe winter weather across the mid-latitudes of the NH.  However, I have to admit as of yet there are no signs of this scenario.  There is still time but not much.  However, there is another scenario that could still yield a relatively cold winter and that is one analogous to what happened in the winter of 2013/14 where no significant disruptions of the stratospheric occurred but rather repeated minor disruptions that yielded a cold winter for central and eastern North America. Though at first, I acknowledged this possibility I was hesitant to favor this scenario.  However, the longer the delay in a major disruption of the stratospheric PV the more I favor this scenario.

The Arctic Oscillation (AO) is currently slightly positive and is predicted to trend slowly negative through the end of the week towards neutral. The forecast is for the AO to remain close to neutral next week, likely a sign of uncertainty.

The current positive AO is reflective of mixed pressure/geopotential height anomalies across the Arctic and mostly positive pressure/geopotential height anomalies across the mid-latitudes. The North Atlantic Oscillation (NAO) is also currently slightly positive with weak pressure/geopotential height anomalies across Greenland and Iceland and positive pressure/geopotential height anomalies across the mid-latitudes of the North Atlantic.

A return to Ural ridging/blocking at the turn of the calendar year favors active energy transfer from the troposphere to the stratosphere. Another pulse is predicted to commence this week and peak the first few days of January. The pulse itself is likely related to relaxation of the pattern and mild temperatures across North America. However, the predicted resultant perturbation to the stratospheric polar vortex (PV) especially the building of heights over northwestern North America in my opinion could once again favor the return of cold temperatures across eastern North America later in January.

Ice did not grow this past week on the North Pacific side of the Arctic basin, still I expect the negative ice anomalies in the region to shrink.  Sea ice is below normal in the Barents-Kara Seas as well and with time the greatest negative sea ice anomalies will likely reside in this region.  As I have been writing for much of the fall I do believe that the record low sea ice anomalies in the Chukchi and Bering Seas has focused ridging/blocking in this region.  Though model forecasts do not predict a return of the blocking in the foreseeable future.

Recent research has shown that regional anomalies are important and the sea ice region most highly correlated with the winter AO is the Barents-Kara Seas region where low Arctic sea ice favors a negative winter AO and a cold Eurasia.  Below normal sea ice in this region may be contributing to more active Wave Activity Flux/poleward heat transport predicted in the models that eventually could result in a negative AO.

Okhotsk Doubles in 12 Days

While the refreezing rate slowed in recent days, we again see contrast in the Pacific Basins.

Mid month, Chukchi (top right) refroze almost completely, then reversed in the last week.  Meanwhile, Okhotsk (Left) grew ice fairly steadily doubling in 12 days to cover nearly half of the annual maximum.  At the moment the Arctic is slightly below the 10 year average, due to the slowdown.

Whichever fork the ice takes, the Polar Bears had a Merry Christmas

 

 

In the first two weeks of December we can see Chukchi at the left filling in with only 8% open water remaining, and Bering starting to freeze. On the right,  Hudson bay is almost fully iced, while Baffin is freezing toward Greenland.  Maximum ice is showing in CAA (Canadian Archipelago), Beaufort, East Siberian, Central Arctic, Laptev and Kara.

Arctic Ice Extents have reached 12M km2, up from 4.6M km2 at Sept. minimum.  This means 50% of the annual maximum has been gained, with 20% of ice cover to be added in the three months before mid March.

The graph compares extents over the first 14 days of December.

2017 has reached 12M km2, close to the 10 year average, while 2012 has recovered with a surplus.  2016 is about 260k km2 behind and 2007 lags by 520k km2.  At this point MASIE and SII are both tracking the 10-year average, with SII about 200k km2 lower.

The Table below shows where ice is located on day 348 in regions of the Arctic ocean. 10 year average comes from 2007 through 2016 inclusive.

Region	2017348	Day 348 Average	2017-Ave.	2007348	2017-2007
(0) Northern_Hemisphere	12022146	12157670	-135524	11501915	520231
(1) Beaufort_Sea	1070445	1069521	924	1062676	7769
(2) Chukchi_Sea	885792	936900	-51108	725062	160730
(3) East_Siberian_Sea	1087120	1083777	3343	1053584	33536
(4) Laptev_Sea	897845	897832	12	897845	0
(5) Kara_Sea	910407	848042	62365	800920	109487
(6) Barents_Sea	229984	354383	-124399	236964	-6980
(7) Greenland_Sea	523005	558656	-35652	488595	34409
(8) Baffin_Bay_Gulf_of_St._Lawrence	835323	825678	9645	793616	41707
(9) Canadian_Archipelago	853109	853052	57	852556	553
(10) Hudson_Bay	1168358	1072919	95439	1217263	-48905
(11) Central_Arctic	3169716	3212523	-42808	3186190	-16475
(12) Bering_Sea	128315	248645	-120329	54836	73479
(13) Baltic_Sea	3933	10542	-6609	2898	1035
(14) Sea_of_Okhotsk	245912	178060	67853	127576	118336

The deficits to average are primarily in Barents and Bering Seas. Surpluses are large in Hudson Bay, Okhotsk and Kara Seas.  Compared to 2007, most seas are in surplus, with only Hudson Bay slightly late.

Footnote

Some people unhappy with the higher amounts of ice extent shown by MASIE continue to claim that Sea Ice Index is the only dataset that can be used. This is false in fact and in logic. Why should anyone accept that the highest quality picture of ice day to day has no shelf life, that one year’s charts can not be compared with another year? Researchers do this analysis, including Walt Meier in charge of Sea Ice Index. That said, I understand his interest in directing people to use his product rather than one he does not control. As I have said before:

MASIE is rigorous, reliable, serves as calibration for satellite products, and uses modern technologies to continue the long and honorable tradition of naval ice charting.  More on this at my post Support MASIE Arctic Ice Dataset

 

This year Hudson Bay added 728k km2 from day 318 to 344 (yesterday).  Nov. 14  showed 280k km2 rising to 1008k on Dec. 10, 2017. About 20% of the basin is yet to freeze.

Arctic Ice Extents have more than doubled since the Sept. minimum and are now up to 10.4M km2.  The last 30% of maximum will take until March, principally because several basins are frozen over and cannot add coverage.  To date, Beaufort and CAA (Canadian Archipelago) are full, as are Laptev and East Siberian on the Russian side.  Kara is 88% covered and the Central Arctic will add only 2% from here.

In the last nine days of November we can see Chukchi at the top adding ice up to 50% of maximum with Beaufort  and East Siberian already frozen.  On the left, Baffin and especially Hudson bay are now growing more strongly.  On the right is Kara filling in with Barents freezing more slowly.

The graph compares extents over the first 25 days of November.

2017 has reached 10.4M km2, 2007 and 2012 nearly the same, and all are close to the 10 year average of 10.6M km2.  2016 is about 1M km2 behind.  At this point MASIE and SII are both tracking the 10-year average, with SII about 200k km2 lower.

The Table below shows where ice is located on day 329 in regions of the Arctic ocean. 10 year average comes from 2007 through 2016 inclusive.

Region	2017329	Day 329 Average	2017-Ave.	2016329	2017-2016
(0) Northern_Hemisphere	10438529	10596102	-157573	9474596	963933
(1) Beaufort_Sea	1070410	1068478	1932	1070445	-35
(2) Chukchi_Sea	516620	793296	-276676	653560	-136940
(3) East_Siberian_Sea	1065427	1082091	-16665	1087137	-21711
(4) Laptev_Sea	897845	897451	394	897211	634
(5) Kara_Sea	826360	732408	93952	328154	498207
(6) Barents_Sea	191448	209544	-18096	31173	160275
(7) Greenland_Sea	414638	542031	-127393	419401	-4763
(8) Baffin_Bay_Gulf_of_St._Lawrence	701761	637760	64001	651237	50524
(9) Canadian_Archipelago	852553	851808	745	853180	-628
(10) Hudson_Bay	632312	422809	209504	267718	364594
(11) Central_Arctic	3182452	3192004	-9552	3082022	100430

The deficits to average are primarily in Chukchi and Greenland Seas. Surpluses are large in Hudson and Baffin Bays, along with Kara Sea.  Compared to last year, Kara, Barents and Hudson Bay all have much greater ice extents.

Footnote

Some people unhappy with the higher amounts of ice extent shown by MASIE continue to claim that Sea Ice Index is the only dataset that can be used. This is false in fact and in logic. Why should anyone accept that the highest quality picture of ice day to day has no shelf life, that one year’s charts can not be compared with another year? Researchers do this analysis, including Walt Meier in charge of Sea Ice Index. That said, I understand his interest in directing people to use his product rather than one he does not control. As I have said before:

MASIE is rigorous, reliable, serves as calibration for satellite products, and uses modern technologies to continue the long and honorable tradition of naval ice charting.  More on this at my post Support MASIE Arctic Ice Dataset

 

Arctic Ice Extents have roughly doubled since the Sept. minimum and are now up to 10M km2.  The last 1/3 of maximum will take until March, principally because several basins are frozen over and cannot add coverage.  To date, Beaufort and CAA (Canadian Archipelago) are full, as are Laptev and East Siberian on the Russian side.  Kara is 3/4 covered and the Central Arctic wil add only 3% from here.

During the first half of November we can see at the bottom Beaufort  and East Siberian filling in, leaving only Chukchi with open water.  On the right, Both Baffin and Hudson bays are now growing more strongly.   At the top Kara ice extent has reached 75% of its March maximum.

The graph compares extents over the first 17 days of November.

2017 has reached 9.9M km2, 2007 nearly the same, and both are close to the 10 year average of 10M km2.  2012 lags 300k km2 lower than 2017, while 2016 is 877k km2 behind.  At this point MASIE and SII are tracking the 10-year average, with SII about 200k km2 lower.

The Table below shows where ice is located on day 321 in regions of the Arctic ocean. 10 year average comes from 2007 through 2016 inclusive.

Region	2017321	Day 321 Average	2017-Ave.	2016304	2017-2016
(0) Northern_Hemisphere	9904268	10013895	-109626	9026577	877691
(1) Beaufort_Sea	1052982	1067181	-14199	1056304	-3322
(2) Chukchi_Sea	449182	702958	-253776	616755	-167573
(3) East_Siberian_Sea	1076201	1077799	-1598	1087137	-10936
(4) Laptev_Sea	897845	897517	328	896732	1113
(5) Kara_Sea	696550	649727	46822	254492	442058
(6) Barents_Sea	68869	174077	-105208	25907	42962
(7) Greenland_Sea	394494	499069	-104575	390593	3901
(8) Baffin_Bay_Gulf_of_St._Lawrence	761453	552922	208531	524708	236745
(9) Canadian_Archipelago	852865	851728	1137	853180	-315
(10) Hudson_Bay	460631	273706	186925	185679	274952
(11) Central_Arctic	3158068	3183076	-25008	3077808	80260

The deficits to average are primarily in Chukchi, also Barents and Greenland Seas. Surpluses are large in Hudson and Baffin Bays, along with Kara Sea.

Footnote

Some people unhappy with the higher amounts of ice extent shown by MASIE continue to claim that Sea Ice Index is the only dataset that can be used. This is false in fact and in logic. Why should anyone accept that the highest quality picture of ice day to day has no shelf life, that one year’s charts can not be compared with another year? Researchers do this analysis, including Walt Meier in charge of Sea Ice Index. That said, I understand his interest in directing people to use his product rather than one he does not control. As I have said before:

MASIE is rigorous, reliable, serves as calibration for satellite products, and uses modern technologies to continue the long and honorable tradition of naval ice charting.  More on this at my post Support MASIE Arctic Ice Dataset

 

Arctic ice extent went over 9M km2 yesterday, or about 60% of annual maximum.  Several seas are already maxed out:  Laptev, East Siberian, Canadian Archipelago.  The image below shows the refreezing this month.

At the bottom watch Beaufort Sea filling in.  On the middle right Baffin Bay steadily adds ice, while Hudson bay starts from its top, but also gets fast ice way down the western coastline into James Bay.  At the top center is Svalbard with Greenland Sea growing on its right, and Kara and Barents filling in on its left.

Dr. Judah Cohen from Atmospheric and Environmental Research (AER) saw this coming.  From his blog November 6 2017:

The forecast for November (Figure 13a) shows cold temperatures in Canada that extend into the Eastern US. The cold temperatures in Canada seem likely but the cold temperatures in the Eastern US will likely depend on the strength of Greenland blocking. The forecast for Eurasia is relatively mild and I think that the forecast is likely to be wrong. In my opinion the predicted blocking across northern Eurasia favors more widespread cold than predicted by the CFS especially across Siberia and East Asia.

My thoughts on the weather pattern over the next several weeks  By Brett Anderson, AccuWeather senior meteorologist  11/08/2017, 4:30:48 PM

Interesting weather pattern setting up across North America as we progress through November and get into early December.

–A series of potent, Pacific storms will likely impact southern BC and the U.S. Pacific Northwest between Nov. 13 and 23. Expect several rounds of heavier rain and gusty winds for Vancouver Island and the mainland coast. Heavy snowfall for the Coastal Range and Rockies should help set the ski season off on a good start.

–A strong Arctic, cold front will press southward through Ontario and Quebec on Thursday. Behind the front, rain showers will quickly change to snow showers and a brief, heavier snow squall. There is the potential for brief whiteout conditions with any squall from southern and eastern Ontario through southern Quebec late Thursday afternoon and into the night. These squalls can quickly drop visibility making travel dangerous for motorists, especially on highways. Roads will generally be wet Thursday afternoon, but untreated roads may briefly get snow covered and icy Thursday evening and night as temperatures rapidly fall below the freezing mark.

In addition to the cold, northwesterly winds will be quite strong Thursday night into early Friday with gusts in the 60- to 80-km/h range from eastern Ontario through Quebec and into western New Brunswick.

Dr. Cohen’s view of the winter Arctic climate system is posted in Snowing and Freezing in the Arctic

As of October 20, 2017, NOAA@NSIDC Releases Sea Ice Index, Version 3.0

Text below from SII webpage explains the changes in versions.

NOAA@NSIDC is pleased to announce the release of Sea Ice Index Version 3 (V3). V3 changes the way the monthly average area and extent data values are calculated. The way monthly average area and extent images are created remains the same as in V2. All daily data remain the same as in V2.

The V3 method simply averages daily extent values, while the V2 method derived monthly average values from the gridded monthly-average concentration field. The change is in response to questions about what seemed to be an inconsistency between daily and monthly values. When users summed daily values, and then divided by number of days in a month to get a monthly average value, that number was different, and sometimes quite different, from the monthly average numbers we presented. Both the V2 and V3 methodologies are valid and defensible ways of representing passive microwave-derived sea ice concentration data, but the goal of this change is to better match the understanding of the user community as the product evolves through time.

Values will change slightly. V3 monthly average areas are slightly greater than those from V2. Conversely, V3 monthly average extents are slightly less than V2. Trends will change slightly as well. These are small changes, as the following images for March, over the entire time series, illustrate. Extent is on the left and area is on the right. Windnagel et al. (2017) offers additional analysis on why V3 areas are higher than V2 and V3 extents are lower than V2, along with a simple example. With the update to V3, there are no considerable differences in conclusions that can be made about the overall trends in sea ice area or extent.

Details are in this report: Sea Ice Index Version 3 Analysis. NSIDC Special Report 19.

The Sea Ice Index version 3 dataset is available here

Background:

Several posts at this blog compare results from MASIE and SII. Walt Meier, head of Sea Ice Index (SII) and colleagues did a comparison of the two datasets, published in October 2015. SII went from version 1 to v.2 in 2016, and then in January 2017 from v.2.0 to v.2.1, with some changes in past values.

One of the biggest discrepancies in the past with previous SII versions arose in the Month of October, and it is timely that version 3.0 appears now. The dataset is now available with past calculations according to v3, and the past can be compared in advance of 2017 monthly results.

For comparison, the graphs below show October monthly averages for MASIE compared to SII v.2 and SII v.3., 2007 through 2016.

It seems clear that SIIv.3 is a big improvement relative to MASIE. And as well, October 2017 results are coming in with the two datasets tracking quite closely.

MASIE: “high-resolution, accurate charts of ice conditions”
Walt Meier, NSIDC, October 2015 article in Annals of Glaciology.