On Thursday 19 April 2012, New Zealand was completely surrounded by a very large High (or anticyclone). The air pressure at sea level was above 1030 hPa everywhere over New Zealand at midday on that day. Highest pressures were over inland Otago and Canterbury, peaking at 1039 hPa. Christchurch Airport was reporting 1038.2 hPa ... that's very high indeed.
After writing two blog posts about lows or depressions, I thought it would be a good idea to also write something about highs or anticyclones. After all, one is just the opposite of the other, isn't it?? Well, in some ways yes, but there are some important differences too.
Part of my job as a teacher of meteorology is to go to NZ universities looking for future meteorologists. It breaks my heart when, sometimes I meet a person with a genuine passion for the weather who would love to work for us as a meteorologist, but just can't cope with the required maths. Unfortunately for them, professional meteorologists need to have some university maths under their belts. And this requirement isn't just a local thing - it also comes from the World Meteorological Organisation of which we are a member nation.
Written by Bob McDavitt, Meteorologist
Today’s weather map shows how this cold southerly is being produced by a combination of a HIGH or anticyclone in the Tasman Sea, and a LOW or depression between Canterbury and the Chatham Islands. For want of a better phrase, we could call this an eggbeater southerly.