As weather forecasters, here at MetService we spend a lot of our time poring through data: data from weather stations, data from satellites and radar, from weather balloons and also webcams. This information is all useful for understanding what the weather is doing right now – but how do we know what might happen in the future? Understanding the current weather helps us understand what might come next, but information from numerical weather models also plays a very important part.
Few weather events are as dramatic, dangerous or challenging to predict as tornadoes.
About the tornado of Tuesday 3 May 2011
On the afternoon of Tuesday 3 May 2011, a line of showers moved southwards across Northland. Ahead of this line the winds were moderate northeasterlies; behind it, they were moderate northwesterlies. Along the line, the winds converged - that is, pushed against each other. Below is a portion of a working chart for 3:00pm Tuesday 3 May 2011, drawn by one of the Severe Weather Forecasters.