The central Atlantic ocean has cooled a little over the last month, and the cold pool that’s been there for what must be a couple of years now has become a little better organised. There are still plenty of pockets of very warm water pulsing south of Newfoundland from the east coast of America, and a noticeable warming of the North sea, probably brought about by the recent exceptional warm start to September in central Europe. The other thing that I noticed was that the warm anomalies of +2 to +3 have now gone from the Davis Straits and the Labrador sea, but the warm anomalous area to the west of Portugal have persisted. Here are two charts of sea surface temperature [SST] anomalies from the last month for comparison. I don’t know what this means for the coming autumn and winter in western Europe, possible another progressive and occasionally stormy affair like the last year.
All the focus recently has been on the Arctic sea ice minimum, but the real news to my mind is in the Antarctic, where a recent late crash in sea ice extent has brought forward the date of maximum extent (18.518 million square kilometres [MSK]) for 2016 to the 28th of August, possibly the earliest maximum in the record that began in 1979. The sea ice extent has fallen from the probable maximum on the 28th of August when it stood at almost +1 standard deviation [SD] above the mean, to now very close to -2 SD below the average. I don’t think it’s likely that it can make this ground up and peak again, because the 18th of September is the average time of maximum extent in the Antarctic. Having said that, there was a late surge in sea ice from the 25th of September last year, the surge continued until October 3rd making it the second latest Antarctic maximum, so anything is possible.
In the last couple of days sea ice extents have rallied a little, but the ice extent currently is third lowest for the 18th of September since 1979, at 96.9% of average. As an aside I have decided not to change my software to use a 5 day running mean as the National Snow and Ice Data Center now do. I like the way I do it for one thing, the other reason is that it would be a tricky programming problem to creates a trailing 5 day mean for the whole series, especially when before 1988 values only came in every other day!
If you think that we’ve had in warm here in the UK during the first 14 days of September then it’s been very much warmer over central Europe with anomalies as high as +6°C. I just wonder if the extreme warm anomalies that occurred over Russia during August, which were as high as +8°C for the entire month, have somehow retrogressed and migrated westwards.
The pressure patterns gives us the reason. The Icelandic low is misplaced, a little further southwest and 11 hPa deeper than usual, whilst a belt of high pressure stretched from the Azores to Poland with pressure anomalies of +4 in the southern Baltic Sea. This produced a conveyor belt of tropical maritime southwesterly for most of northwest Europe, but sunny, very warm or hot anticyclonic conditions for much of central Europe.