General August Weather

[NZ Thunderstorm Soc]

Another day of cloud and clagg. 11.1C for today with 0.7mm of occasional drizzle. Light NE.

[Awhituobs]

another warm night here, 14c most of the night
that has pushed my average temperature month to date to +0.6c
and another warm day and night still too come
monday and tuesday will be colder nights with the easterly change but warm and sunny afternoons
and another blocking high with east or NE wind across NZ for the first week of September
this is unusual ..La Nina written all over it
maybe we are heading for a strong La Nina spring and summer

[harleyb]

GFS prog for Tuesday. It's not often you see a pressure difference of more than 100 hPa between a high and the adjacent low...

aus2.72hr.png

[NZ Thunderstorm Soc]

A generally cloudy day with light winds.
Came onto light rain from later this afternoon with 4mm falling to 10pm tonight.
11.1C for today.

[Awhituobs]

wasn't there a big solar flare and potential effects on earth about now...coincidence re space weather effects and this recent 200 mm rain ?

[TonyT]

wasn't there a big solar flare and potential effects on earth about now...coincidence re space weather effects and this recent 200 mm rain ?

There was a recent flare but it wasn't major. An M4 I think from memory. There would be some geomagnetic storming going on currently from that, but not a huge energy input. I'd be looking more at the SSTs in the Tasman as supporting moist uplift.

[Awhituobs]

and a redeveloping La Nina...and the fact its been such a warm winter overall,..i.e so yes warm ocean

[TonyT]

and a redeveloping La Nina...and the fact its been such a warm winter overall,..i.e so yes warm ocean

Eastern Tasman definitely THE zone currently.

cdas-sflux_ssta_swpac_1.png

[NZ Thunderstorm Soc]

After a frosty start, a fine day eventuated with a cool but light NE wind, not like what occurred in Auckland that was not RED warned by MS.
Maybe Mods could make this a separate topic on this as it looked like it was a significant event.
Today's maximum was 11.6C.

[Nev]

... not like what occurred in Auckland that was not RED warned by MS.
Maybe Mods could make this a separate topic on this as it looked like it was a significant event.

Done.

[Cyclone Tracy]

August 2021 stats locally –

Mean daily temp = 12.3c ( same as 2018/20 average)
Rainfall = 109.4mm (-3mm 2001/2020 average)
Prevailing wind SW
3 thunder days. (ave 3.3)
Humidity 80.2% (-2.1% average)

YTD
Daily temp 16.31c , -0.15c average (2018/2020)
Rainfall 542mm , -271mm average (2001/2020)

[David]

Howick - August 2021

Summary
Slightly warmer than average. Frequent rain but nothing particularly heavy (locally at this particular location). Rainfall was very near average but fell a few mm short, making it the 6th consecutive month to not reach/exceed the average.

Stats
Mean temp = 11.8C (+0.4C)
Mean daily high = 15.8C (+0.2C)
Mean daily low = 8.6C (+0.9C)
Highest temp = 18.9C (on day 17)
Lowest temp = 1.6C (on day 10)
Total rainfall= 131mm (-4mm, or 97% of average)
YTD rainfall = 686mm (-176mm, or 80% of average)

[Awhituobs]

141mm here for August, above average for me
temperature was 0.7C above average (20 years of data)

[Nev]

August was another relatively warm month overall, particularly in the South Island. Generally drier and sunnier in the east and wetter and cloudier in the west.

MetService August 2021 Summary - A sting in winter’s tail

The final month of meteorological winter was dominated by negative Southern Annular Mode (a measure of how stormy the Southern Ocean is) and negative SAM means enhanced westerlies for New Zealand, especially South Island. Whilst these westerlies did indeed throw front after front at the West Coast delivering well above average August rain from Fiordland to Farewell Spit, it was the slower moving features which made the most impact. A slow-moving feature brought heavy rain and damaging winds to central New Zealand on the 8th followed by a sharp southerly change and snow.

The westerlies soon returned though, continuing to run drier than average for eastern South Island south of Kaikoura as well as eastern North Island. The rest of North Island, apart from Auckland, had near normal rainfall in August, picking up the scraps of the westerly fronts from South Island between dry spells thanks to recurring high pressure. Auckland was tracking the same way until late in the month when high pressure sat to the east, then edged south, slowing down an approaching Tasman low, which brought persistent, heavy, flooding rain to Auckland.

August 2021 Climate Anomaly Maps ℅ NIWA.png

Preliminary August 2021 figures for the main centres:

Code: Select all

Aug 2021 Average Temps, Rainfall, Sunshine and departures from 1981-2010 normals ℅ NIWA

Site                     T-max °C      T-min °C      T-mean °C     Rain mm      Sun hrs

Auckland, Mangere       15.8  +0.8     8.9  +0.7    12.3  +0.7    104   92%    160  109%
Auckland Aero           15.8  +0.9     8.8  +0.6    12.3  +0.7     91   82%
Tauranga Aero           15.5  +0.5     7.1  +0.4    11.3  +0.5     42   38%    n/a   n/a
Hamilton Aero           14.8  +0.1     4.7  +0.2     9.8  +0.2    143  120%
Hamilton, Ruakura       15.1  +0.5     5.1  +0.1    10.1  +0.3    112  102%    122   85%
Wellington, Kelburn     12.3  +0.1     7.4  +0.7     9.9  +0.5    148  127%    129   88%
Christchurch Aero       13.1  +0.7     3.0  +1.0     8.1  +0.9     80  128%    157  102%
Dunedin, Musselburgh    13.0  +1.8     5.3  +1.1     9.1  +1.4     44   80%    144  118%
Greymouth Aero          13.3  +0.5     6.2  +1.1     9.7  +0.8    234  122%    115   90%

[NZ Thunderstorm Soc]

10 frosts were recorded this month..
Minimum for the month was 3.6C below zero recorded on the 21st.
Maximum for the month was 23.3C on the 24th.
Lowest maximum was 5C on the 8th with the highest minimum being 7.8C on the 1st.
58.6mm of rain in total over 15 days.

[Awhituobs]

I guess in a few days they will know how the 3 month average came out re records
I see Niwa 0.7 is exactly the same as mine for Auckland

[Cyclone Tracy]

Locally, 2020's winter was warmer by 0.2 than this 2021 winter for me. Looking at Nev's 9 station preliminary stats he loads each month for 9 stations, 2020 was marginally warmer at 10.39c compared to this year 10.36c.

[Nev]

Locally, 2020's winter was warmer by 0.2 than this 2021 winter for me. Looking at Nev's 9 station preliminary stats he loads each month for 9 stations, 2020 was marginally warmer at 10.39c compared to this year 10.36c.

I wouldn't use all those main centre sites (+ Greymouth) as an overveiw, as it's a little bias towards the north, i.e. I normally include 2 sites for Akld (Mangere for main centre figures and Akld Aero for the national Seven Station Series (7SS), and 2 sites for Hamilton (Hamilton Aero for main centre temps and rainfall, and Ruakura for sunshine). Greymouth is just to add some west coast balance.

NIWA's preliminary national 7SS figures suggest that this winter may be about 0.2C warmer than last year's record winter.

[Cyclone Tracy]

Locally, 2020's winter was warmer by 0.2 than this 2021 winter for me. Looking at Nev's 9 station preliminary stats he loads each month for 9 stations, 2020 was marginally warmer at 10.39c compared to this year 10.36c.

I wouldn't use all those main centre sites (+ Greymouth) as an overveiw, as it's a little bias towards the north, i.e. I normally include 2 sites for Akld (Mangere for main centre figures and Akld Aero for the national Seven Station Series (7SS), and 2 sites for Hamilton (Hamilton Aero for main centre temps and rainfall, and Ruakura for sunshine). Greymouth is just to add some west coast balance.

NIWA's preliminary national 7SS figures suggest that this winter may be about 0.2C warmer than last year's record winter.

Fair enough. I was just posting my local observations and having a glance at the sites you post each month, my post was not related to NIWA's 7SS.

[Awhituobs]

ding ding ding so this winter is a winner? lol

[Nev]

From today's NIWA Winter 2021 Climate Summary:

Winter 2021 was the warmest winter on record in Aotearoa New Zealand, surpassing winter 2020 that set the record just last year.

The nationwide average temperature for winter 2021 was 9.7°C (1.3°C above the 1981-2010 average from NIWA’s seven-station temperature series which begins in 1909), making winter 2021 the warmest winter on record.

https://twitter.com/NiwaWeather/status/ ... 0422780947

[Razor]

From today's NIWA Winter 2021 Climate Summary:

Winter 2021 was the warmest winter on record in Aotearoa New Zealand, surpassing winter 2020 that set the record just last year.

The nationwide average temperature for winter 2021 was 9.7°C (1.3°C above the 1981-2010 average from NIWA’s seven-station temperature series which begins in 1909), making winter 2021 the warmest winter on record.

https://twitter.com/NiwaWeather/status/ ... 0422780947

The key statement I took was 76 locations had a record or near record warm winter

[Awhituobs]

1.3c is astonishing!

[tich]

From today's NIWA Winter 2021 Climate Summary:

Winter 2021 was the warmest winter on record in Aotearoa New Zealand, surpassing winter 2020 that set the record just last year.

The nationwide average temperature for winter 2021 was 9.7°C (1.3°C above the 1981-2010 average from NIWA’s seven-station temperature series which begins in 1909), making winter 2021 the warmest winter on record.

https://twitter.com/NiwaWeather/status/ ... 0422780947

Warmest on record - until next winter. Or will there be a change in weather patterns by then?

[Awhituobs]

I would suggest next winter will be more of a building towards an El Nino spring
but lingering warm tasman waters from a La Nina summer will mean a warm start to winter
that's my crystal ball gaze educated guess