Strange Data from ONS

What's going on in Britain's trade balance? Given that the 2Q current account deficit was a record  £20.8bn blowout largely owing to the £28.1bn deficit in traded goods, one would imagine it is easy to tell. But it isn't:

• in June  the £4.33bn trade deficit reported was far larger than the range of analysts' expectations;  
• in July, a dramatic recovery in the deficit, to just £1.71bn similarly defied the range of analysts' expectations, and
• in August, the deficit ballooned again, to £4.17bn - once again, completely unexpected.

Now this is seasonally adjusted data, which usually suppresses monthly volatility (there are exceptions -  Japan's 1Q GDP, for example). But right now, the volatility of Britain's export performance is extremely unusual.  Consider this chart of Britain's export of goods, data from the Office for National Statistics: 

This year, the data is showing a monthly volatility quite unlike anything we've previously seen. This can be measured: during 2000 to the end of 2011, the monthly change in Britain's exports had a standard deviation of 4% a month. This year, that volatility has jumped to 7.2%. It is as if, come 2012, we are dealing with a completely different population of data. 

To make matters more puzzling, this spike in volatility shows up nowhere else in Britain's trade data: exports of services, imports of goods, imports of services -  all these have retained their historic  volatility pattern. 

 I have emailed the ONS seeking an explanation. If they reply, I will post it here. 

In the meantime, if one wants to track Britain's trading trends, it makes more sense to smooth - in this case to a 6m average. It's bad. . . . but probably not as bad as the monthly data has announced.