In my blog post about winds aloft there is a loop of satellite images for a week in winter 2008. It shows that the big cloud features in the mid-latitudes typically travel from west to east. In other words, the features you see on weather maps affecting New Zealand have usually started out roughly in the area of southern Australia.
On the night of 17th July and early on the 18th, New Zealand was affected by a fast-moving and rapidly deepening depression originating in the north Tasman Sea. Sustained southwesterly winds of more than 60 knots were recorded in Colville Channel as the low passed by. Severe Weather Warnings were issued for wind in Coromandel/Great Barrier Island and rain in the eastern North Island.
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.
When I was biking to work this morning I noticed prolific amounts of pine pollen in the puddles around Westhaven.
Bledislow cup weather forecast
I find it fascinating that there is so much pattern in our weather, and I find it frustrating when, sometimes, chaotically, one of them behaves slightly differently, as in this case producing wayward winds for Auckland.
If you were in New Zealand in the mid '70s you may remember a particularly strong wind-storm that devastated many parts of the eastern South Island. It struck on 1 August 1975, doing a huge amount of damage to pine trees in the Eyrewell and Balmoral forests in particular.
To give you an idea of the power of this storm, some of the peak recorded winds and gusts were:
From Wednesday 01 July 2009, MetService will provide a Severe Thunderstorm Warning Service. This blog entry explains why we're now able to do this, why warnings of thunderstorms are different from warnings of broad-scale weather events, which parts of New Zealand they will apply for, how you can receive them and what actions you can take to protect yourself.
MetService weather forecasters naturally spend a lot of time looking at satellite imagery and every so often are treated to some fascinating cloud patterns in the airflows around New Zealand. One pattern I've always liked seeing is the Kármán Vortex street, most frequently observed near our shores to the west of the North Island, generated by Mt Taranaki in a south to southeast flow.