Direction analysis of strong wind gusts at Kelburn

Archive of NZ Weather & Climate
Forum rules
These topics are a read-only archive and may be subject to out-of-date information.

For today's weather discussion head to: New Zealand Weather & Climate
Locked
RWood
Posts: 3745
Joined: Sat 24/01/2004 16:56
Location: Wellington
Has thanked: 188 times
Been thanked: 123 times

Direction analysis of strong wind gusts at Kelburn

Unread post by RWood »

The comment about strong westerly-concentrated winds at a site in Island Bay led me to check the data for Kelburn - direction of the maximum daily gusts over 1972-2007 - with a handful of missing days, that is almost exactly 13,000 observations. Tables are in the attached workbook. The results are more or less what I expected. The "16 point" directional breakdown has NW as 31% of the total. The lowest frequency, WSW (and also W to some extent), I associate particularly with post-frontal conditions in typical westerly scenarios, often marked by very bright and clear sunny conditions with pleasantly lowish humidity and very little wind. The lowest rate on the "other side" of the compass is ENE (E not far behind), which was common in months like March 2003 - anticyclonic and very sunny and warm.

It's noteworthy that 3 of the 24-hour periods in the original data showed total calms (max. gust zero, or presumably at least too small to register). One of these, in late June 1982, was part of a 39-hour calm spell. As the instrument is on a pole at least 15m high on a fairly exposed hillside, that is reasonably impressive.

In the 10-degree table, the 210 direction is well down the list at 1% - but that was the sustained wind direction and max. gust direction on Wahine day.
Kelburn gust direction frequencies 1972-2007, summary.xls
You do not have the required permissions to view the files attached to this post.
User avatar
Michael
Posts: 7210
Joined: Thu 27/03/2003 12:04
Location: Rainy Manurewa, Auckland - "City of Gales"
Has thanked: 0
Been thanked: 1 time
Contact:

Re: Direction analysis of strong wind gusts at Kelburn

Unread post by Michael »

The Mana one has it at 301° which is almost NW but Island Bay had it fluctuating WWSW ie 250° and mostly WNW today but some W.
RWood
Posts: 3745
Joined: Sat 24/01/2004 16:56
Location: Wellington
Has thanked: 188 times
Been thanked: 123 times

Re: Direction analysis of strong wind gusts at Kelburn

Unread post by RWood »

Yesterday was clear in a regional flow of about WSW/W - a common scenario. The response over most of the city and a hill where I walked was fluctuating between light winds (relating to the WSW) and some stronger ones from WNW (more westerly phases of winds getting bent through the Cook gap).
Locked