General February Weather

[Richard]

The low cloud that came in at dawn doesnt look like it will break, clear sky should be back again once the airflow turn more to the NW.

[TonyT]

The low cloud that came in at dawn doesnt look like it will break, clear sky should be back again once the airflow turn more to the NW.

I would pick a bit more of an easterly influence for the next month or two, fewer days of proper northwest flow.

[jamie]

I must sound like a stuck record but.....Less than 8mm in 66 days. No rain for what could be another 10 days. I’m intrigued to see if we can can to 80 days with less than 10mm of rain but at the same time I’m just simply praying for rain.

I’ve looked back at all the droughts since 2008 on this station and this one (pardon my french) shits all over anything else. 08 and 13 were not as severe as this.


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[Awhituobs]

I remember the droughts of the 70,s here
I was young
But i remember the grass being all white
But we didnt have any kikuyu
Then 1979 was our wettest year on record by far

[TonyT]

I must sound like a stuck record but.....Less than 8mm in 66 days. No rain for what could be another 10 days. I’m intrigued to see if we can can to 80 days with less than 10mm of rain but at the same time I’m just simply praying for rain.

I’ve looked back at all the droughts since 2008 on this station and this one (pardon my french) shits all over anything else. 08 and 13 were not as severe as this.


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There is some hope

Looking at the ECMWF ensemble members only 12% are at 15mm or less by Tuesday 10th March, but 22% are over 70mm, and the ensemble mean is near 60mm. The GFS ensemble is less bullish about rain with an ensemble mean of 35mm by Wednesday 11th, but 30% of members are over 50mm.

Looking longer term at the six week ECMWF data, no ensemble members are below 60mm by April 9th, over 60% of them are above 150mm, and the ensemble mean is near 200mm. Most of that is going to fall after about March 20th. Help is on the way!

[NZ Thunderstorm Soc]

Another fine day with a maximum of 22.8C.

[Awhituobs]

is not looking hopeful for rain for NI currently on the models any time soon
(not until well into march now )
whats going on lol

[NZstorm]

Yes, looks dry for the next 10 days. 30C at Hamilton for the next 7 days.

April is the month where a general synoptic change occurs with the polar jet making a resurgance north although some years that won't happen until May.

[Awhituobs]

it was still dry here the start of June last year
don't want a repeat of that again

[spwill]

Around here is similar to 2013 with very little rain in January, a dry Feb but with one moderate fall of rain.
March is still warm season with usually plenty of settled weather.

[Chris Raine]

2.4 mm of rain yesterday and threatening to west .I see lightning in the Tasman Sea with the next front

[cbm]

I must sound like a stuck record but.....Less than 8mm in 66 days. No rain for what could be another 10 days. I’m intrigued to see if we can can to 80 days with less than 10mm of rain but at the same time I’m just simply praying for rain.

I’ve looked back at all the droughts since 2008 on this station and this one (pardon my french) shits all over anything else. 08 and 13 were not as severe as this.


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I did that spreadsheet as I wanted to see if it had been this totally dry before. Seemingly not. The only time that compares was way back in 1908. As it has turned out, the 2.4mm that Ruakura got on Sunday means it will just avoid breaking the Jan + Feb total record from 1908, but not by much and way less than now 3rd placed 2013.
The "famous" droughts of 1945/46, 77/78 and even now 2008 and 2013 are staring to look tame compared to this.
What I have not seen is any expert nominate an immediate cause for this current drought. Or maybe they have and I have missed it?

[James]

So what caused it in 1908?

[cbm]

We will never know. They would barely have had weather forecasting back then. Just barometers. And we have to trust what will have been 1 set of written records had no error, i.e. that it actually happened.

[Cyclone Tracy]

My 2 cents worth -

Today's composite chart combining 850, 500 & 300 hPa is very similar to 2013 as displayed below. Moisture steering west at the top of Oz by a stubborn ridge around NZ. Tropical cyclones are no match for a ridge like this. The only weather system on earth that can change the pattern is an upper polar low. In 2013, the polar jet broke the pattern and produced Auckland's wettest May on record.

I'm working on a theory on what is causing the 2019/20 drought.... but still a few gaps in my theory

[Awhituobs]

australia is a bit like a big rock in a river and you get down stream eddies....this blocking ridge is a bit like that..a down stream eddie

[Orion]

We will never know. They would barely have had weather forecasting back then. Just barometers. And we have to trust what will have been 1 set of written records had no error, i.e. that it actually happened.

600 BC – First public weather forecasts ...

1860 – Co-ordinated weather forecasting
Fitzroy in England is collecting data and publishing his weather forecasts and the Smithsonian Institution in America is doing the same. Over the next few years, meteorological organisations are set up worldwide.

1861 NZ Government involved in meteorology

1874 Storm warnings issued to ships and harbours in NZ

1882 First weather maps published in NZ

1905 – Ship to shore weather reports...

Source, with further details:

https://www.sciencelearn.org.nz/interac ... a-timeline

[James]

Could it be related to
Re: Sudden Stratospheric Warming Event (SH) 2019?

[Awhituobs]

I doubt it as that was not an affect in 2013 which has a similar pattern
the SSW some said was going to give us a colder than spring /summer
that didnt happen although there was some short cold snap at times (background global warming offset meant we were close to being a colder than normal spring but not in the end)

[Richard]

australia is a bit like a big rock in a river and you get down stream eddies....this blocking ridge is a bit like that..a down stream eddie

Yes, I reckon that sounds quite plausible

[Richard]

Warmth back again here today after a few cooler days, 28,4 deg the max

[Cyclone Tracy]

Could it be related to
Re: Sudden Stratospheric Warming Event (SH) 2019?

Yep, for sure. 1 large piece of the puzzle but it takes months to flush out and has caused the cooler dry NZ January (compared to the last few) and continued meridional flow on either side of the ridge. Melbourne looks like they will have their coolest Feb for 15 years.

[Chris W]

australia is a bit like a big rock in a river and you get down stream eddies....this blocking ridge is a bit like that..a down stream eddie

Yes, I reckon that sounds quite plausible

I think there's something to be said for that - the vortex shift caused by the SSW created a pool of air with broadly different temperature to the vortex to the south and the tropics to the north, basically in the position of the blocking high as it is now. This drove the polar jet southeast of us as I may have commented in the SSW thread...here we go https://www.weatherforum.nz/phpBB3/view ... 01#p188501. The subtropical ridge north of us to my memory was also weakened by the event, setting up an easterly flow that is now around the top of the blocking high. I could be talking rubbish, but I'm curious.

70hPa wind:
https://earth.nullschool.net/#current/w ... 73,-38.625
70hPa temp:
https://earth.nullschool.net/#current/w ... 73,-38.625

[TonyT]

We will never know. They would barely have had weather forecasting back then. Just barometers. And we have to trust what will have been 1 set of written records had no error, i.e. that it actually happened.

According to Noaa, 1907/08 was ENSO neutral, sandwiched between a Nino 1906 and a Nina 1909

2012/13 was also neutral

see https://www.esrl.noaa.gov/psd/enso/past_events.html

Neutral seasons don't favour either the northwards movement of the westerlies and their associated fronts, or the southwards movement of sub-tropical systems.

[TonyT]

I doubt it as that was not an affect in 2013 which has a similar pattern
the SSW some said was going to give us a colder than spring /summer
that didnt happen although there was some short cold snap at times (background global warming offset meant we were close to being a colder than normal spring but not in the end)

We've had this argument before, but just for the record, there were cooler than normal months in the 2019 spring.

Just because there wasn't a SSW event in 2013 doesn't mean that it wasn't an influence this time around. There may well be multiple factors which result in a synoptic pattern which causes drought, and you might not need all of them at the same time to get the result. Equally, it could be largely a co-incidence, an outcome of quasi-random processes which just happened to mean no rain for Waikato in 2013 and 2020. Having said that, I can distinctly recall going to Fonterra early in the 12/13 summer to tell them there were strong signs of extended dryness in the Waikato and other areas, and being politely told to go away, we don't want to know. So I guess it was predictable to a degree.