Spring Westerlies

[Philip Duncan]

Actually nevermind... That's still different to saying "gusting to gale force" which was the comment made to me earlier this year. In saying that, in the USA a gust is measured by 1 minute whereas it's 10mins here...that's a big difference!

[Manukau heads obs]

i dont think that is correct
the average windspeed for a METAR is a 10 minute period
if the gusts in that period are 10 knots higher than that average, then a METAR will report, gusting to...

[David]

Quite a cool breeze today, though it got to 16.6oC.

A weather station I had noticed 38 houses down my street a few months ago has online data that I only just came across, here: http://www.janter.co.nz/weather/index.htm

The setup there looks reasonable but the temp. sensor is somewhat too high up in the air (all sensors mounted on a tall pole I think). Great to see my wind readings are consistent with its readings. Don't know what's with the high rainfall reports there - I find it difficult to believe 39mm more rain this month just 38 houses down the road, and 74mm more for August! And I suspected my digital gauge over-estimated rainfall....

There is another setup within 15mins walk of here also...there I've seen a roof anemometer, and some other apparatus including a rain bucket mounted on the fence there. Must be a growing weather interest in this area.

[Manukau heads obs]

i see they are using the chinese made WH1081 station
that has a very small rain gauge (smallest I have seen for a electronic weather station), and so will not be all that accurate

[Nev]

...in the USA a gust is measured by 1 minute whereas it's 10mins here...that's a big difference!

Agree with Brian. The duration of a gust is usually less than 20 seconds and in the US is measured as the maximum 3 second wind speed within a 2 minute period. The WMO definition for sustained winds is based on a 10 minute average at 10 metres above ground level and is the aviation industry standard which is also used by most weather agencies worldwide. The US Saffir-Simpson Scale does however use 1 minute averages when categorising hurricanes, which can generally be about 14% higher than 10 minute averages.

[TonyT]

@Phil - there is a basic difference between gales and severe gales assuming MetService are using the terms correctly from the Beaufort Scale. However, its also possible that they simply added the word "severe" in there to make sure the media picked it up and reported it. However, the difference is in the mean speeds expected, not the gust speeds. The Beaufort Scale has no relevance to wind gusts, which is why the term "gusts to gale force" has no meaning. Its as pointless as saying "wow, it was warm today, must have been at least 5kw out there". Kiliowatts is what we measure heat from a heater with isnt it?

There is also plenty of evidence to suggest that 10 minute averaged mean speeds of high winds correlate a lot better with potential damage than gust speeds, so perhaps this media obsession with gusts is rather irrelevant anyway. A bit like the public obsession with today's maximum temperatures as a gauge of how "good" the weather is around the country.

As an example consider the Canterbury nor'wester, one of the gustiest winds in the world if you care to define "gustiness" by the ratio of peak gust speed (usually measured over 3 seconds, which was the resolution of the old Munro chart recorders, and which has become the de facto standard for a gust) to mean speed. So, Canterbury often sees winds averaging 50kmh but gusting to 100kmh, yet without much (if any) property damage. However, a gust of 100kmh in many parts of the world (maybe even Auckland) would be associated with property damage because it would generally only occur with an associated mean speed of say 60-70kmh. Its the mean speed which matters the most.

[Inny Binny]

Blardy hell it's windy out there. We're normally pretty sheltred from the wind but it's damn strong this time.

[tich]

Windy too in Central Chch - this time the northwesterlies have reached us. But a cold southerly looks like it's coming this afternoon. It's already hit the far south - Tradme posters report snow and sleet in northern Southland, and Queenstown was down to 3C at 9am. (with 7mm in previous hour)

[southernthrash]

Yea, heavy snow in Arrowtown apparently

[gllitz]

Yea, heavy snow in Arrowtown apparently

Yup, webcam shows that, too: http://homepages.ihug.co.nz/~jim.ryan/weather/

Far out, wouldn't THAT be a kicker, if it snowed here with this change coming...the M/S rural Canty forecast (when you look at Darfield, Ashburton, Timuaru, etc for the 3 days temp and rain chart) shows a pretty dramatic change in temps this arvo...all that energy has to go somewhere, I guess... I personally don't see it happening, but it hasn't really warmed up all that much yet today...

[southernthrash]

Jims weather station is good eh?

Pictures of snow near Arrowtown this morning: http://forums.ski.com.au/forums/ubbthre ... Post516550

The temperature drop was pretty sudden in the Wakatipu. Thinking I might see a bit of snow on the road between Dunedin and Invercargill, heading off soon, and to the Remarkables tomorrow. Definitely a marked change from the warm wind in Dunedin last night.

[Philip Duncan]

Nev/Tony - thanks for the feedback. That's quite interesting to read.
Yes many certainly like to know our extremes even if, as you point out, the gusts aren't actually a true measure of extreme. I wrote a blog a while back about perhaps mentioning a rough "average" temperature for the next day rather than a "high"...which got some very interesting feedback (on both sides).

Cheers again
Phil.

[trickytiger]

been sleeting here in Temuka since just after 12pm

[Storm Struck]

Is it just me or is that an echo on the 2pm radar .
Just starting to lightly rain here now with a temperature going from 11-10C at times.
Cheers
Jason.

[spwill]

At noon Wanaka was on 2C and Oamaru on 5C.

[Smeagol]

Can someone explain why it is snowing very heavily at my place? Haha SNOW!!!!!!!

[Inny Binny]

My grandmother just rang to tell me it's snowing in Darfield too.

[melja]

Can someone explain why it is snowing very heavily at my place? Haha SNOW!!!!!!!

Because we pay M/S for s#@t forcasts

Heavy sleet here in rangiora now and 3.9C

[jamie]

The radar looks nasty.. is that the snow that is causing it like i have noticed on other snow events or is the rain just that heavy?

[CHCH Weather Chaser]

Yes, a very intense looking rain radar at 430pm with very heavy falls in parts of the city showing atm!! 9.6mm here so far with peak rate of 9mm/h.

[NZ Thunderstorm Soc]

Down to 0.9C here in West Melton at the moment.
Rain more lighter and WSW not as strong as before.
Haven't checked the rain-gauge yet but we've had a good drop this afternoon.

JohnGaul
NZTS

[Inny Binny]

It's now cooling really fast...this is very interesting...

EDIT: 3 degrees a Chch airport!

[Ryan Thomas]

Holy **** dropped from 4.9 to 3.6 in 10 mins at Jeffs, didn't expect it to get this cold.

[Storm Struck]

Only light rain here so far infact only 1mm in the rain gauge although that does look set to change going by the 5pm radar which suggests some heavy stuff coming.
Looks to be a rather quick clearance moving into south canterbury now obviously there is some weakening going on.
Cheers
Jason.

[CHCH Weather Chaser]

yes and stil dropping. 3.3 dont think itll get less than 2.5 though.