NIWA’s storm information update

NIWA Media Release 21 June 2013
NIWA’s storm information update

• NIWA has been measuring wave height from a buoy two kilometres off Baring Head, Wellington, since 1995. Last night’s waves are the largest seen in that record.

• Last night, the highest waves measured were typically 15 metres, from peak to trough, for the period around midnight last night.

• Anecdotal information records the wave height at the time of the Wahine disaster at 12 to 14 metres.

How do the winds in Wellington associated with yesterday’s storm compare with winds from other storms over the last 50 years?

• Long term wind measurements have been taken at Wellington Airport since 1960, making it a reliable site to gauge the force of southerly storms as it is exposed directly to the southerly wind.

• The maximum 10 minute average, sustained wind reading, recorded at the airport was 101km/hour, with individual gusts typically up to 130-140 km/hour.

• These measurement show that last night’s storm is in the same category as five other major storms recorded in 1961, 1965, 1967, 1974, 1977 and 1985.

• The maximum 10 minute average, sustained wind reading during the Wahine disaster was measured at 144 km/hour and stand out by far as the strongest in the 50 years of the record.

• So this was an extreme event, but still not as intense as the Wahine storm.

How severe is the snow storm?

• The largest snow storm on record in the central South Island was registered in 1973.

• Snow depth recorded by NIWA staff at Methven yesterday was 99mm compared with 610mm snow depth measured in 1973.

• At Lake Tekapo, the snow depth of 600mm measured yesterday was similar to the 670mm measured in 1973.

• The snow depth recorded on the inland road near Waiau yesterday was 229mm, slightly more than the 161mm recorded last year.

Please credit the graph to NIWA and attribute the release Dr Murray Poulter.

ENDS

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