General January Weather

[melja]

Arthur's pass reached about 30C but then dropped sharply to 16C mid afternoon in what looks to have been a thunderstorm.

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[cbm]

Windy is only showing SST of 20.5C for Tasman Sea, Raglan area. But out there today saw lowest 21.5 and highest 23.8 at 50m. Overheard some who had been out wide trolling for Marlin that they encountered some patches of 26/27C! Surely must be mistaken. Unless maybe the very top few cm had been heated by the sun. Was very glassy till about 1pm.

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[Richard]

Arthur's pass reached about 30C but then dropped sharply to 16C mid afternoon in what looks to have been a thunderstorm.

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They were sizeable storms too, pity there weren't more rain gauges up there, there would have been some impressive recordings, be great to know if any did..anyone?, there's a 'thanked' in it for ya

[Razor]

Reports coming on of lightning causing fires both at lake Tennyson and Lake Sumner this evening. Worrying stuff with the great and wind ahead

[NZ Thunderstorm Soc]

Windy is only showing SST of 20.5C for Tasman Sea, Raglan area. But out there today saw lowest 21.5 and highest 23.8 at 50m. Overheard some who had been out wide trolling for Marlin that they encountered some patches of 26/27C! Surely must be mistaken. Unless maybe the very top few cm had been heated by the sun. Was very glassy till about 1pm.

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....imm sorry, I don't know what you are talking about???

[cbm]

SST = Sea Surface Temperature. Saying this map on windy.com is underrepresenting the Tasman Sea Temperatures, that's significant as warm Tasman Sea SST will fuel the deep low expected this week, for which there is a thread.

Screenshot from 2018-01-28 22-25-26.jpg

The chart on swellmap.com generally agrees with what I saw out in the boat today. It's showing patches of over 24C just off Greymouth.

Screenshot from 2018-01-28 22-43-12.jpg

[Nev]

Friends out sailing around the Gulf over the last few days were measuring SST's of around 24C.

[Chris Raine]

Metservice have a rain gauge /climat site on the western end of the car park at the railway station at Arthurs Pass.*t was registering 21.3mm /hr at one point this evening

[NZ Thunderstorm Soc]

SST = Sea Surface Temperature. Saying this map on windy.com is underrepresenting the Tasman Sea Temperatures, that's significant as warm Tasman Sea SST will fuel the deep low expected this week, for which there is a thread.

Thanks. I didn't realize it was a marine site.

[David]

Mean temperature in Howick for January was 21.9C (averaged over 1 minute intervals). Easily the warmest month in my station records. Jan 2017 was only 18.7C.

The mean daily max was 26.1C and mean daily min 18.6C, which would give a traditional mean of 22.4C.

[Razor]

In our hood the mean Maximum was also 26.1. Maximum high was 35.3 and the overall mean was 20.1. Ten days exceeded 30 degrees.

111mm of rain, which mostly fell in three days in the first week. Wind much less than normal

NIWA stats will be interesting I expect a number of broken records around NZ

[Nev]

January 2018 was New Zealand's warmest January on record.

MetService January 2018 Summary

High pressure frequently sat east of the country, and over the south of the South Island, during January. In contrast, several very intense lows developed over the north Tasman Sea during the month (4th, 10-11th and 16-18th). These lows intermittently produced extremely heavy rain for northern regions of both Islands. The most significant of these systems occurred on 4 January, producing extreme heavy rain and gales across most of the North Island, as well as in the northern South Island. This event also resulted in coastal inundation in lower-lying coastal areas of the upper North Island.

January rainfall totals were subsequently well above normal across the North Island (excluding Gisborne and Hawke's Bay), as well as in Nelson, Marlborough and Canterbury. However, the lack of rainmakers over the far south of the country was striking in comparison. The extended heat and dryness over southern New Zealand resulted in an extension of the drought classification into Otago and Southland on 30 January.

Humid northeast winds prevailed across New Zealand during the month, and the combination of these winds, and the pre-existing marine heat-wave (see below),produced record-breaking January heat.

Jan 2018 Climate Anomaly Maps ℅ NIWA.gif

Some very preliminary January 2018 figures for the main centres:

Code: Select all

Jan 2018 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       25.8  +2.4    19.0  +3.1    22.4  +2.8    121  198%    212   91%
Auckland Aero           26.1  +2.5    18.9  +2.9    22.5  +2.7     66   99%
Tauranga Aero           25.3  +1.4    18.9  +3.8    22.1  +2.6    136  173%    n/a   n/a
Hamilton Aero           26.3  +2.0    16.5  +4.1    21.4  +3.1    112  136%
Hamilton, Ruakura       26.7  +2.7    15.8  +2.9    21.3  +2.9    275  347%    188   82%
Wellington, Kelburn     23.5  +3.2    17.2  +3.7    20.4  +3.5     86  114%    210   85%
Christchurch Aero       24.4  +1.8    15.3  +3.4    19.9  +2.7    115  320%    221   93%
Dunedin, Musselburgh    21.6  +2.7    14.7  +3.1    18.1  +2.8     54   74%    244  135%
Greymouth Aero          22.9  +3.1    16.7  +4.3    19.8  +3.7    306  146%    217  108%

All six main centre sites recorded their highest ever January average T-means, T-mins and, except for Hamilton's Ruakura and Dunedin's Musselburgh, their highest T-maxs.

[RWood]

A hot month, but not a sunny one. Should also be confirmed as NZ's warmest recorded month. Kelburn total sun is missing one day which MetService did record - I have asked a NIWA person to sort it out if possible.

[Nev]

^ Yes, I did notice that NIWA was missing Kelburn's sunshine for the 7th. However, it looked fairly cloudy that day going by Metar's, so the difference is probably only minor, if at all…

[cbm]

Ruakura must have caught an isolated downpour or two. A Davis 6465M which I installed and remotely administer where family farm, about 10km East of Hamilton Airport, only recorded 86.6mm for the month.

[RWood]

^ Yes, I did notice that NIWA was missing Kelburn's sunshine for the 7th. However, it looked fairly cloudy that day going by Metar's, so the difference is probably only minor, if at all…

I kept track of the daily numbers from MetService's reports in the paper - the difference was about 7-9 hours, from the discrepancy in MTD totals. If NIWA don't come through I'll try and get the reading from a back copy of the DomPost. Tomorrow's paper should show the monthly total around 218.5.

[spwill]

it is interesting to compare the numbers at Mangere this January with January 2017

2018, mean temp 22.4, rain 121mm, sunshine 212hrs, considered a very good January
2017, mean temp19C, rain 36mm, sunshine 242hrs, was considered a poor January

[David]

Is the 66mm at Akl Airport correct? Nearby Mangere showing 121mm, which is closer to what much of the region got.

[Nev]

Ruakura must have caught an isolated downpour or two. A Davis 6465M which I installed and remotely administer where family farm, about 10km East of Hamilton Airport, only recorded 86.6mm for the month.

Yes, I think there might be a serious error with NIWA's Ruakura daily rainfall data. Their 9am figures totalling 274mm doesn't correspond at all with their with calendar-day figures totalling 110mm, which is more consistent with Hamilton Aero's total of 112mm about 10km to the south.

Mangere's rainfall figures also looks very suspicious, as each daily rainfall looks to be consistently about twice that of Auckland Aero, which is only about 5 km to the south.

Edit: Sorry David, just saw your post above. Yes, maybe it's Akld Aero that's out?

[RWood]

Kelburn's Tmean for January was more than 1.1C higher than that of Feb 1998. One cool night with a Tmin of 11.9C spoilt the chance of easily beating the record high value for the monthly minimum (12.4C in Jan 1975), as the next coolest night only dropped to 14.2C (quick check of the numbers). Also, the record high Tmin of 20.0C in Feb 1998 has been equalled twice in recent days.

[RWood]

it is interesting to compare the numbers at Mangere this January with January 2017

2018, mean temp 22.4, rain 121mm, sunshine 212hrs, considered a very good January
2017, mean temp19C, rain 36mm, sunshine 242hrs, was considered a poor January

The old "temp versus sun" thing (mainly). Locally the exceptionally warm January was really good for hitting the beaches around the region (as of course water temps were also well above average). But I missed the comparative absence of blue-dome days. I rate January 1965 here as the best one for Wellington, very warm (about 2.5C above average) but also very sunny with 304 hours recorded. Rainfall was modest at 58mm. Unfortunately I didn't experience much of that, apart from passing through on a holiday. Most of the month was spent in the south where it was mild but very cloudy (and was followed by a really lousy Feb & autumn).

[RWood]

January 2018 was New Zealand's warmest January on record.



Jan 2018 Climate Anomaly Maps ℅ NIWA.gif


Some very preliminary January 2018 figures for the main centres:

Code: Select all

Jan 2018 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       25.8  +2.4    19.0  +3.1    22.4  +2.8    121  198%    212   91%
Auckland Aero           26.1  +2.5    18.9  +2.9    22.5  +2.7     66   99%
Tauranga Aero           25.3  +1.4    18.9  +3.8    22.1  +2.6    136  173%    n/a   n/a
Hamilton Aero           26.3  +2.0    16.5  +4.1    21.4  +3.1    112  136%
Hamilton, Ruakura       26.7  +2.7    15.8  +2.9    21.3  +2.9    275  347%    188   82%
Wellington, Kelburn     23.5  +3.2    17.2  +3.7    20.4  +3.5     86  114%    210   85%
Christchurch Aero       24.4  +1.8    15.3  +3.4    19.9  +2.7    115  320%    221   93%
Dunedin, Musselburgh    21.6  +2.7    14.7  +3.1    18.1  +2.8     54   74%    244  135%
Greymouth Aero          22.9  +3.1    16.7  +4.3    19.8  +3.7    306  146%    217  108%

All six main centre sites recorded their highest ever January average T-means, T-mins and, except for Hamilton's Ruakura and Dunedin's Musselburgh, their highest T-maxs.

Report is now available on the website. As with December, no analysis or comment on sunshine anomalies except for the 6 main centres (plus a caveat), confirming the implied admission in the 2017 annual report that comparing electronic readings with normals based on manual data is pretty meaningless. We have had a lot of "sunny" months in the last few years ...
the annual report comments say an investigation into the matter is being done (well overdue, too).

[RWood]

^ Yes, I did notice that NIWA was missing Kelburn's sunshine for the 7th. However, it looked fairly cloudy that day going by Metar's, so the difference is probably only minor, if at all…

I confirmed that Metservice's report in the Dompost of the 9th cited a sunshine reading of 8.9 hours for the 7th, giving a monthly toal of 218.4 (still well below average). After 2 cloudy years in a row (at least according the manual readings), we need all the help we can get!

[NZstorm]

it is interesting to compare the numbers at Mangere this January with January 2017

2018, mean temp 22.4, rain 121mm, sunshine 212hrs, considered a very good January
2017, mean temp19C, rain 36mm, sunshine 242hrs, was considered a poor January

The best January in recent years in Auckland was 2015. Sunshine over 300hrs, rain 6mm, average daily max 25.4C and not very humid.

[spwill]

I confirmed that Metservice's report in the Dompost of the 9th cited a sunshine reading of 8.9 hours for the 7th, giving a monthly toal of 218.4 (still well below average). After 2 cloudy years in a row (at least according the manual readings), we need all the help we can get!

There will be variation in sunshine hrs around Wellington and Hutt valley with all the hills and valleys. Auckland will have variation in sunshine hrs across the region due to covergence cloud lines created by the hills, harbours and east v west coast. Over my house it can be cloudy for hrs with sea breeze convergence cloud while 2 km down the road it stays sunny.