VegetableBen: Weed it and Reap!: Chaotic weather, storms, drought and the AO index

What a difference a year makes - oh and we still have concerns over on-going drought conditions!

Icicle on bird feeder in Dec 2010

This time last year it was very cold and we had the 2nd coldest Decembers on record. This year we got the 2nd warmest autumn on record and December is turning into a very stormy, mild and chaotic weather month. Last week, exceptionally strong hurricane-like winds battered Scotland, some over 100MPH. Oh and we could still be in drought conditions.

See: Scotland battered by worst storm for 10 years
See: Drought warning for England

Early warning of big storms to hit Midlands next week..will post more in next blog if turns out correct! UPDATE: Not as severely windy but still windy.

Here is a long rang pressure map for next Friday over the UK. Tight isobars over Scotland, N. Ireland, North and N. Midlands, so strong winds likely from Northwest. Have read gusts of 50+MPH over Midlands and 70+MPH over Scotland.

Source: @StuOstro on Twitter

The Arctic Oscillation Index (AO)

If you are interested in forecasting UK weather patterns during winter, take a look at what the AO index is up to. See: AO Data / Graph

In the winter, UK weather patterns will be effected by the AO in the following ways:

When the AO is positive we get warmer air sucked up from Equator and Atlantic, so more likely to get low pressure storms sent our way. Although more warm and chaotic, we could get brief heavy snow / sleet showers where the warm air meets cold and even snow lighting!!
When AO is negative we get more blocking high pressure sitting over us and cold air dragged in from Arctic / northern Europe. Weather is sunnier but bitterly cold and dry.

See more: http://nsidc.org/arcticmet/patterns/arctic_oscillation.html

Source: @StuOstro on Twitter

StuOstro (twitter) has provided a useful graphic of the difference in AO for 2009/2010/2011.

Looking at the Dec average temps - you can perhaps see the effect of the AO:

2009 = -1.5°C (below average, 99th coldest on record)
2010 = -5.3°C (below average, 2nd coldest on record)
2011 = currently +1°C (above average, but off a record breaking Nov of +3°C above average)

Early crops

As you can see from previous posts, my early peas, broad beans and onions are up and growing. This isn't a big problem as long as the weather stays mild over the winter, and I have covered them. However, we did get some overnight lows of -2°C and sleet/snow on friday.

December photos