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.

Might maritime activities, such as shipping, oil extraction, fishing etc. be having an effect on Barents Sea ice extents?  Arnd Bernaerts has an informative post up at his blog: They warm-up the Arctic! Shipping, Off-Shore, Science etc.!

Dr. Bernaerts explains:

It is not known which alterations shipping, naval forces, research vessels and off-shore industry cause in the Arctic Ocean sea-body structure, whether ice covered or not, and the subsequent impact on the annual sea ice and the polar-weather, called climate change. Bad that science has no idea about this human Arctic warming aspect. Worse, science has never rose, or ever been willing to raise and investigate the subject. At least you will face a hard time to find anything in this respect.

When considering the possible impact of ocean uses on climate change, any activities at sea north of the Polar Circle is a multifold higher than in any other Ocean region. Between the Arctic Ocean and the Equator the climatic impact of human activities the difference could be several hundred, if not thousand times, due to extreme narrow structure margin concerning water temperature and salinity. The temperature range in the upper 150 meter sea surface level is minus 2° to plus 4°C. Arctic salinity is down to 30ppt in places, while the oceans vary between 34ppt and 36ppt. So far it is statistics, and they are ‘wrong’ if not properly applied.

Navigating and other ocean uses in Arctic sea areas without knowing the impact is irresponsible. Navigating through compact ice is even worse, as the force of ship screws may travel over long distances, with significant changes to sea temperatures and salinity.

Summary

The whole article is informative and raises important questions (and not for the first time).  Time to stop obsessing over CO2, the “magic” gas, and try to understand real human impacts.

A Russian liquid gas tanker (LNG) “Christophe de Margerie” just set two Arctic records few weeks ago (Details). The ship not only traveled through the Arctic in record time, but has done so without the use of an icebreaker escort. She is the first of a total of 15 planned LNG carriers that will be gradually deployed.

 

With the most typical day for annual minimum a week away, watching Arctic ice is like watching an ocean liner coasting to a halt before reversing engines.  A recent post reported that ice extents  are stabilizing around 4.7M km2 in recent days, and more importantly, some refreezing in the central seas.  As discussed in Arctic Heart Beat, the marginal shelf seas seldom have ice at annual minimum, typically on or about day 260.  The image below shows the progression of ice extents from 2007 to 2017 on day 254 with six days to go.

 

Yesterday was day 254 and the graph below shows 2017 compared with other years and the decadal average during the last 3 weeks.

For the last week MASIE and SII are showing the same extent, now about 70k km2 above the 10 year average.  Only four years in the decade had more ice on this day.  2007 is 300k km2 lower, 2016 500k km2 lower, and at the bottom is 2012 1.1M km2 below 2017.  A recent post on August storms discussed the dramatic impact on 2012 and 2016, which is evident as well in the chart.  The table compares 2017, decadal average and 2007 for the regions containing ice at this time.

Region	2017254	Day 254 Average	2017-Ave.	2007254	2017-2007
(0) Northern_Hemisphere	4652293	4583359	68934	4349612	302681
(1) Beaufort_Sea	393863	480306	-86443	599679	-205815
(2) Chukchi_Sea	131705	173275	-41570	74733	56973
(3) East_Siberian_Sea	279268	286737	-7468	311	278957
(4) Laptev_Sea	205794	149612	56182	247496	-41702
(5) Kara_Sea	18486	29190	-10705	62274	-43788
(6) Barents_Sea	4313	25209	-20896	7384	-3071
(7) Greenland_Sea	107969	211322	-103353	324789	-216820
(8) Baffin_Bay_Gulf_of_St._Lawrence	45146	22235	22911	21406	23740
(9) Canadian_Archipelago	370958	262283	108675	210083	160875
(10) Hudson_Bay	1432	11057	-9625	16552	-15120
(11) Central_Arctic	3092201	2931173	161028	2783651	308551

The deficits continue to be on the Pacific side, especially Beaufort, and also Greenland Sea is down this year.  These are more than offset by large surpluses in the Central Arctic and Canadian Archipelago, and also Laptev.  East Siberian sea also has surplus ice this year compared to 2007.

September 5, 2017 Dr. Judah Cohen of AER posted his monthly forecast for the Arctic and NH based on the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO).  Excerpts below.

The AO is currently slightly negative (Figure 1), reflective of mostly positive geopotential height anomalies across the Arctic and mixed geopotential height anomalies across the mid-latitudes of the NH (Figure 2). Geopotential height anomalies are mostly negative across Greenland and Iceland (Figure 2), and therefore the NAO is slightly positive.
Figure 1. (a) The predicted daily-mean near-surface AO from the 00Z 5 September 2017 GFS ensemble. Gray lines indicate the AO index from each individual ensemble member, with the ensemble-mean AO index given by the red line with squares.

The AO is predicted to straddle neutral next week as geopotential height anomalies remain mixed across the Arctic. Similarly, with mixed geopotential height anomalies stretching across Greenland and Iceland, the NAO will likely be near neutral as well.  

(Note: AO and NAO are signed differently than one might expect; the reference point is outside the Arctic itself.  Thus negative phases of these indices mean higher pressures in the Arctic and lower outside, while positive phases indicate lower pressures in the Arctic.  Now that the Arctic sun is setting, the main issue for ice extent is storminess which requires low Arctic pressures.)

Impacts

It is the first week of fall, a season of transition from summer to winter. One important sign IMO of this seasonal transition is the return of the polar vortex in the stratosphere. The models predict the possible formation of the polar vortex sometime next week. Starting in October, I will be watching variability in the polar vortex for signs of pattern changes in the weather across the NH.

Another sign of the seasonal transition is the minimum in Arctic sea ice extent, which will be achieved in the coming days and/or weeks. The trajectory of sea ice melt has slowed since early August. In my last blog I suggested the possibility that the sea ice minimum could be similar to the years 2008 and 2010 and that is looking more likely but is difficult to predict. Over the coming months, I will be following Arctic sea ice variability for signs of the severity of the upcoming winter. Our understanding for how anomalies in sea ice extent influence the weather in the mid-latitudes is still immature IMO but I do think that important progress has been made recently.

Another sign of the transition from summer to winter is the return of snowfall to the NH. Snowfall over the sea ice in August probably helped retard the melt of sea ice and snowfall is now even occurring over Siberia and Alaska but is still very regionalized. Again I will be monitoring the advance of snow cover extent across the continents for signs of the strength of the polar vortex and the possible resultant weather.

Finally I find it interesting that while the atmospheric circulation has transitioned from the dominant summer pattern across Eurasia it has not across North America. The dominant summer pattern across Eurasia was ridging across Europe (with the exception of Northern Europe) and East Asia but with troughing in Western Asia. The forecast for the coming weeks is the opposite with troughs across Europe and East Asia but ridging in Western Asia. This is an overall cooler pattern than the dominant summer pattern. However across North America there are no similar signs of transition. The dominant summer pattern was strong ridging across western North America and troughing in eastern North America and at least for now that pattern looks to continue for much of the month of September. I don’t know the reason behind the persistent western ridge/eastern trough pattern across North America but how long this pattern can persist will obviously have important implications for the weather across North America in the coming months.

Summary

Bottom line, looks like September weather will be ordinary in the Arctic with seasonal cooling in the NH.  Dr. Cohen also thinks the annual ice extent minimum will be near average for the decade.  While the monthly average is final only at September end, this week will set the tone and likely result.

 

 

It is a few days earlier than usual, but MASIE shows ice extents  stabilizing near 4.7M km2 in recent days, and more importantly, some refreezing in the central seas.  As discussed in Arctic Heart Beat, the marginal shelf seas seldom have ice at annual minimum, typically on or about day 260.  The image below shows the progression of ice extents from 2007 to 2017.

Yesterday was day 251 and the graph below shows 2017 compared with other years and the decadal average during the last 3 weeks.

At this point MASIE and SII are showing the same extent, about 100k km2 above the 10 year average.  2007 is 250k km2 lower, 2016 500k km2 lower, and at the bottom is 2012 1.1M km2 below 2017.  The table compares 2017, decadal average and 2007 for the regions containing ice at this time.

Region	2017251	Day 251 Average	2017-Ave.	2007251	2017-2007
(0) Northern_Hemisphere	4716948	4619900	97048	4467771	249177
(1) Beaufort_Sea	409067	492365	-83298	643868	-234801
(2) Chukchi_Sea	133345	185601	-52257	95240	38105
(3) East_Siberian_Sea	279966	301146	-21180	311	279655
(4) Laptev_Sea	196236	152840	43396	252479	-56243
(5) Kara_Sea	22449	30277	-7828	59593	-37144
(6) Barents_Sea	23123	20028	3095	5882	17240
(7) Greenland_Sea	116132	196719	-80586	315125	-198993
(8) Baffin_Bay_Gulf_of_St._Lawrence	46799	21575	25224	17173	29626
(9) Canadian_Archipelago	374084	268736	105348	236583	137501
(10) Hudson_Bay	1191	11933	-10743	22646	-21455
(11) Central_Arctic	3113399	2937746	175653	2817614	295785

The deficits continue to be on the Pacific side, especially Beaufort, and also Greenland Sea is down this year.  These are more than offset by large surpluses in the Central Arctic and Canadian Archipelago, and also Laptev.  East Siberian sea also has surplus ice this year compared to 2007.

September 5, 2017 Dr. Judah Cohen of AER posted his monthly forecast for the Arctic and NH based on the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO).  Excerpts below.

The AO is currently slightly negative (Figure 1), reflective of mostly positive geopotential height anomalies across the Arctic and mixed geopotential height anomalies across the mid-latitudes of the NH (Figure 2). Geopotential height anomalies are mostly negative across Greenland and Iceland (Figure 2), and therefore the NAO is slightly positive.
Figure 1. (a) The predicted daily-mean near-surface AO from the 00Z 5 September 2017 GFS ensemble. Gray lines indicate the AO index from each individual ensemble member, with the ensemble-mean AO index given by the red line with squares.

The AO is predicted to straddle neutral next week as geopotential height anomalies remain mixed across the Arctic. Similarly, with mixed geopotential height anomalies stretching across Greenland and Iceland, the NAO will likely be near neutral as well.  

(Note: AO and NAO are signed differently than one might expect; the reference point is outside the Arctic itself.  Thus negative phases of these indices mean higher pressures in the Arctic and lower outside, while positive phases indicate lower pressures in the Arctic.  Now that the Arctic sun is setting, the main issue for ice extent is storminess which requires low Arctic pressures.)

Impacts

It is the first week of fall, a season of transition from summer to winter. One important sign IMO of this seasonal transition is the return of the polar vortex in the stratosphere. The models predict the possible formation of the polar vortex sometime next week. Starting in October, I will be watching variability in the polar vortex for signs of pattern changes in the weather across the NH.

Another sign of the seasonal transition is the minimum in Arctic sea ice extent, which will be achieved in the coming days and/or weeks. The trajectory of sea ice melt has slowed since early August. In my last blog I suggested the possibility that the sea ice minimum could be similar to the years 2008 and 2010 and that is looking more likely but is difficult to predict. Over the coming months, I will be following Arctic sea ice variability for signs of the severity of the upcoming winter. Our understanding for how anomalies in sea ice extent influence the weather in the mid-latitudes is still immature IMO but I do think that important progress has been made recently.

Another sign of the transition from summer to winter is the return of snowfall to the NH. Snowfall over the sea ice in August probably helped retard the melt of sea ice and snowfall is now even occurring over Siberia and Alaska but is still very regionalized. Again I will be monitoring the advance of snow cover extent across the continents for signs of the strength of the polar vortex and the possible resultant weather.

Finally I find it interesting that while the atmospheric circulation has transitioned from the dominant summer pattern across Eurasia it has not across North America. The dominant summer pattern across Eurasia was ridging across Europe (with the exception of Northern Europe) and East Asia but with troughing in Western Asia. The forecast for the coming weeks is the opposite with troughs across Europe and East Asia but ridging in Western Asia. This is an overall cooler pattern than the dominant summer pattern. However across North America there are no similar signs of transition. The dominant summer pattern was strong ridging across western North America and troughing in eastern North America and at least for now that pattern looks to continue for much of the month of September. I don’t know the reason behind the persistent western ridge/eastern trough pattern across North America but how long this pattern can persist will obviously have important implications for the weather across North America in the coming months.

Summary

Bottom line, looks like September weather will be ordinary in the Arctic with seasonal cooling in the NH.  Dr. Cohen also thinks the annual ice extent minimum will be near average for the decade.  While the monthly average is final only at September end, the next week will set the tone and likely result.