Tropical Cyclone Pam Updates - Tuesday 10 March 2015

Update for Tuesday afternoon, 10 March 2015


The latest guidance and advice from the Fiji Meteorological Service has upgraded Tropical Cyclone Pam to a category 2. This means that sustained wind speeds close to the centre of the system are in excess of 90km/h. The system is forecast to continue strengthening as it moves slowly to the southeast. At 1pm, New Zealand time, TC Pam was located at 9.7°S 170.4°E, with a central pressure of 985hPa. The latest track and position information can be found on the Fiji Met Service website.

Sea State and Swell

By Sarah Haddon, Meteorologist

The MetService team produces both coastal and recreational marine forecasts. Part of these forecasts includes the state of the sea and the swell. But what is the difference?

Firstly, it is important to understand how a wave is described. Figure one shows the different characteristics of a wave.

The Southern Annular Mode (or SAM)

New Zealand lies mid-way between the tropics and the Southern Ocean, and our day-to-day weather can arrive from either direction. On a longer time scale (weeks to months), tropical weather is influenced by the state of the El Nino-Southern Oscillation (ENSO). The ENSO climate pattern affects wind flows, rainfall distribution and sea temperatures right across the tropics, from equatorial South America to Indonesia. It also has some effect on New Zealand’s climate (winds, temperatures and rainfall patterns), although generally to a lesser degree than in the tropics.