General February Weather

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Chris W
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General February Weather

Unread post by Chris W »

Looking like we’re in for a hot start, a cool-off and then maybe something more settled in the first week or so alone. Not sure what to expect beyond that, there has been talk of the MJO having an influence maybe meaning some troughing later on?
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Re: General February Weather

Unread post by TonyT »

Chris W wrote: Mon 27/01/2020 11:56 Looking like we’re in for a hot start, a cool-off and then maybe something more settled in the first week or so alone. Not sure what to expect beyond that, there has been talk of the MJO having an influence maybe meaning some troughing later on?
No indications of significant MJO activity at this stage. Best bet is to look for another dry, sunny, anticylonic month IMHO, with the best chance of troughing mid month, around the start of the third week. But I suspect it will be a brief interlude, not a permanent change.

BOM wants to keep the MJO in the neutral zone, after a brief flirt with phase 5/6 (more anticyclonic northerlies) in the next week. Most models are similar. GEFS is the outlier at present, suggesting a moderate phase 2/3 in the second week of the month, which if it comes off would mean some NW/SW troughing.
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Re: General February Weather

Unread post by Awhituobs »

that is a change from ideas only a few says ago then
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Re: General February Weather

Unread post by TonyT »

Awhituobs wrote: Mon 27/01/2020 15:39 that is a change from ideas only a few says ago then
Not a change in my expectations, no. Entirely consistent and similar to what I wrote in the January thread a few days ago.
TonyT wrote: Sat 25/01/2020 08:49 Well, yes. Not unexpected, but there we are. Its certainly been an intense dry spell this month, and will remain so up to the third week in Feb which is your best chance for some rain in the next six weeks. It will likely get very dry again after that.
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Re: General February Weather

Unread post by Awhituobs »

ECMWF has the idea of a low approaching from the north Tasman (which GFS was playing around with that idea too)
from 6th Feb
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Re: General February Weather

Unread post by jamie »

Looks to be a bloody hot start to the month at this stage.

Tony I recall you saying back in early Jan that you wouldn’t be surprised if those warm temps right at the start of the year we’re going to be the hottest of the year and that the rest of summer might not deliver hot weather. What was driving that thinking then, compared to now? Not having a dig here. Just curious to know what has changed in the atmosphere considering mid 30’s is looking possible for widespread areas.

I’m getting rather worried about the extra hot and dry temps we are getting coupled with the non existent rain. Looks to me like a major drought is building very quickly now.


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Re: General February Weather

Unread post by TonyT »

jamie wrote: Tue 28/01/2020 08:48 Looks to be a bloody hot start to the month at this stage.

Tony I recall you saying back in early Jan that you wouldn’t be surprised if those warm temps right at the start of the year we’re going to be the hottest of the year and that the rest of summer might not deliver hot weather. What was driving that thinking then, compared to now? Not having a dig here. Just curious to know what has changed in the atmosphere considering mid 30’s is looking possible for widespread areas.

I’m getting rather worried about the extra hot and dry temps we are getting coupled with the non existent rain. Looks to me like a major drought is building very quickly now.


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A very good and fair question, so forgive me if I take my time to answer.

Firstly, your recollection is close but not quite right. What i wrote was:
TonyT wrote: Tue 31/12/2019 11:32 I'll make a bold call - 1st January will be the hottest day of 2020 for some locations.

Lets try a little crystal ball gazing. ECMWF is projecting a strong MJO phase 4 and 5 to develop in the second week of January. For us that usually means an approaching anticyclone with some southerly quarter flow; then the anticyclone passing over, then milder northerly quarter flow as it moves away. Given the forecast strength of this MJO pulse, then if this verifies the trend should be pretty clear over NZ.
The prediction of a very hot Jan 1st was driven by peculiar circumstances on that particular day, it was a prediction for one day, not a comment to be taken to mean anything for the whole season. I certainly didn't suggest that the rest of the summer would not deliver hot weather nor intend to imply that (in fact I was trying to imply the opposite with my use of the phrase "milder northerly quarter flow"). While there are times that I will hint at ideas with what I write rather than state them outright, for the most part you should take what I write literally! The MJO progression I expected has come about (and now finished), and we did indeed get a cool start to the month with approaching high pressure as predicted, and have had a warmer period with light northerly flow subsequently, also as predicted. Both of these trends have been entirely consistent with the relevant phases of the strong MJO pulse which has pushed though.

On the 11th I wrote:
TonyT wrote: Sat 11/01/2020 20:21 I'd pick a trough arriving in the last 3-5 days of the month to bring some rain to most areas, especially the north. But very dry either side of that. Most models are pushing the MJO into phase 6 with good amplitude in 10 days time, and some on into phase 7 for the last week of the month. Phase 6 is the start of sub-tropical low pressure spreading southwards towards the far north; phase 7 is when troughs impact the far north (last week of the month), and if it carries on to phase 8 thats the full monty for low pressure over the country. The GFS is the most bullish about this MJO swing, so its not being internally consistent if it wants to keep northern NZ dry through the last 10 days of the month IMHO.
And as we now know the MJO did continue strongly into phase 7 last week, but has hit the brick wall and failed to reach phase 8 (which is a shame for those looking for rain). In the end, the GFS had it right!

On the 16th I posted the BOM forecast MJO chart and wrote:
TonyT wrote: Thu 16/01/2020 13:37 Latest BOM MJO forecast has us move strongly through phase 6 currently, rapidly and strongly across phase 7 from Sunday to Tuesday, then a slow decline and decay in phase 8 for the rest of the month. Phase 6 is the anticyclones to the east and northeast airflow phase (tick that box), phase 7 is the troughs approaching the country from the north and west phase, and phase 8 is the phase which favours troughs over and around the country. This is a strong MJO signal (about as strong as it gets), and so far the phase 4/5/6 transition over the last 10 days has produced pretty typical outcomes.
As it turns out the BOM model missed the mark and didn't pick the sudden decline of the MJO while in phase 7. So we wont reach a phase 8 state this time round. Which is why we wont see significant rain at the end of the month (although some places will pick up a little later this week).

What I didn't post here, but did tease on my FB page on 10th January was this:
Update going out to clients next week with a prediction for February to April based on pattern matching with recent and current atmospheric trends over and around Australia - the past is giving us the hint that its looking drier and sunnier than normal for much of New Zealand for a few months or more. But, warmer or cooler? And, will it all come crashing down during April?

This was based on pattern matching of similar seasons.

And at that time clients for the six-weeek/seasonal outlook intel got to read this:
It’s interesting to look back and track what seems to me to be a pretty good run of predictions in recent months. As far back as late mid-November we were expecting an unsettled and cooler period between Christmas and New Year, extending into the first week of January. That expectation remained in the outlooks through December and certainly verified. From mid-December we were pushing the idea of a significant period of high pressure for the last two thirds of January, bringing a sudden change from unsettled weather to very settled with increased sunshine and little rain. That is currently verifying strongly as well (although the easterly airflow has caught the east of the North Island in cloud and coolness, but even that was predicted in the update sent out just before Christmas).
The big weather story being pushed by the media in recent weeks has been the fires in Australia, which have been described as unprecedented (they are not), and which have been attributed to the “driest period on record”, which its not. Looking back on this event it will rank as one of the driest in the last 150 years, but its interesting to see that the October to December periods in both 1977 and 2002 were similar, and in some places a little drier. Further digging has revealed that many atmospheric characteristics over and around Australia in both those seasons bore strong similarities to 2019 (although neither were solar minimum years). That opens the possibility to use those seasons as analogues to base a forecast off for the next few months, and that is exactly what I have done.
In ‘77 and ‘02 the Decembers in New Zealand were dominated by more frequent west to southwest airflow, and wetter in western areas, but drier in the east. So that’s a good match to 2019. The ‘78 and ‘03 Januarys were dominated by anticyclones and higher than normal air pressure, so that’s a strong match to the pattern we are now under (and looks likely to persist through to near the end of this month). Both years were sunnier and drier than normal, but one was warmer than usual, and one cooler.
The ’78 and ’02 Februarys were both very similar to each other, and to the Januarys preceding them. They were dominated by anticyclones, especially over the South Island. Both were very dry and very sunny, but again one was warm, one was cold. The Marchs of those two years were similar again – with more anticyclones over the country and higher than usual air pressures, so consequently for the third month in a row most areas were drier and sunnier than normal, and some areas were experiencing drought conditions (brought about by lack of rainfall, not drying winds). The exceptions were the far north and east of the North Island, and the far south and southwest of the South Island which caught some rain from passing low pressure systems.
So, both of our potential analogue years had a very dry, sunny January to March period, dominated by higher than usual air pressure with anticyclones lingering over the country. Both trended towards drought, but with the extremities of the country (far north and eastern coasts of the North Island; the south coast, and southwest of the South Island) less dry. The similarity between both years is strong, and, so far, the similarity to this season is strong also.
And what happened in the Aprils of ’78 and ’03? Both Aprils saw a big change in weather patterns from the previous three months with frequent visits from low pressure systems and periods of easterly airflow. Both years saw some floods and periods of heavy rain, although in different parts of the country, and droughts in most areas were well and truly broken, with too much rain being more of a problem than too little. Sunshine was in short supply.
Now there are no guarantees in this game of pin-the-cloud-on-the-island that our 2020 January to April period will be the same, but the odds are certainly tilted in that direction. So, look out for a significantly sunnier and drier January to March period for most parts of New Zealand, as anticyclones remain dominant and low-pressure rain systems only get to the extremities of both islands. There is no clear indication of warmer or colder, so maybe expect a bit of both. And watch out for April 2020 – it could bring a major shift to low pressure systems and rain.


Now folks on here didn't get to read that last bit (and the subsequent updates) because I have to keep some material back for paying clients, because I have to earn a living at this game! (and on that note Jamie, if you want to stay up to date with my thoughts then please subscribe, many Waikato farmers already do). But I think it shows that my thinking on this season has been pretty consistent, is backed by solid intel, and for the most part things are working out as I expected them to.

As for your last comment, I think you are right to be concerned about major drought, and have hinted at such both on this forum but more specifically in the outlooks. However, I still (for now!) stand behind the idea that although February and March are likely to be dry overall, you will see some periods where rain is more likely than at other times, and the principal one will be around the middle of Feb or early in the third week. you may also see a similar period mid-March. (and both of these could lead a colder than normal week, just to keep us on our toes). So your total rainfall for the month might not be too far from normal, but your number of rain days will very likely be lower than normal. Does that make sense?

I've shown you all this because I want you to appreciate that a lot of work (which you don't usually get to see) lies behind the words I write on this forum. However, please don't assume that what I write here is the sum total of my work on any given subject - its often only part of a bigger picture. I hope that by sharing tidbits and opinions here that I can help everyone in this community understand and get more enjoyment out of the weather (and I'm acutely aware that part of the enjoyment is making, or watching others make, predictions, and seeing how they pan out - I'm up for that, willing to fall flat on my face sometimes!). But if you want my actual advice and intel to work with in your business, then don't expect to get it off a weather forum where I post primarily for other enthusiasts enjoyment and education.
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General February Weather

Unread post by jamie »

Cheers Tony. Comprehensive to say the least
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Re: General February Weather

Unread post by Razor »

Thanks for sharing Tony, its a privilege for us to have your insights here

7 day forecast here in ChCh is for unusually prolonged heatwave by the looks. I've been running every day the past week in the Port hills and its an absolute tinderbox up there. Some sheep grazing in some areas is knocking fuel back but fingers crossed no one is stupid with fire this year.
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Re: General February Weather

Unread post by cbm »

Awhituobs wrote:ECMWF has the idea of a low approaching from the north Tasman (which GFS was playing around with that idea too)
from 6th Feb
Was getting hopeful when I saw that too, but it has disappeared with the model update, at least for the run that windy.com shows. Know you're getting desperate when get excited over a low more than a week out in the model runs.

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Re: General February Weather

Unread post by Awhituobs »

yeah...but at least it showed up in more than 1 model the idea
hopefully it means it might come back into the model runs again
I don't want the 8000 trees I planted dying because of a prolonged drought!
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Re: General February Weather

Unread post by cbm »

Awhituobs wrote:yeah...but at least it showed up in more than 1 model the idea
hopefully it means it might come back into the model runs again
I don't want the 8000 trees I planted dying because of a prolonged drought!
Yes, that is a point. Scary when I look at photos from this time last year, knowing how dry it got by March. Locally at least, it's way worse now than the final week of Jan 2019.

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Re: General February Weather

Unread post by Cyclone Tracy »

2 cents worth –

There are signs of a planetary scale equatorial rossby wave stimulating 2 cyclonic vortices on either side of the equator within the next 5 days. The meridional distance scale of this wave is about 20° of latitude since the centers are located roughly 10° either side of the equator. They look to have an ER wave fingerprint all over them. The monsoon trough will dip and strengthen if it verifies. Models could become volatile within the next 5 days in the tropics. If an upper trough from the south launches into the ridge and weakens it, an open exit door for the moisture could mean an NZ impact within the next 2 weeks.
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Re: General February Weather

Unread post by harleyb »

Warm out east over the coming week. That's a serious run of warm days in the forecast, even for Hawkes Bay.
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Re: General February Weather

Unread post by Nev »

harleyb wrote: Wed 29/01/2020 19:29 Warm out east over the coming week. That's a serious run of warm days in the forecast, even for Hawkes Bay.

image.png
I see MS have revised Hastings T-max on Saturday down to around 29C. Could still be a rare 7-day heatwave though if Saturday's T-max gets above 28.7C (i.e. normal Feb T-max of 23.7C + 5.0C).
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Re: General February Weather

Unread post by jamie »

Question about heat waves. Should the definition of one be from std dev rather than average? East coast places have a lower average max temp than inland places, but because they are east they can also have very high temps. Meaning it’s easier for a east coast place to reach heat wave criteria. If std dev was used, the high range of temps along east coast would be taken into account.


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Re: General February Weather

Unread post by TonyT »

jamie wrote: Wed 29/01/2020 21:10 Question about heat waves. Should the definition of one be from std dev rather than average? East coast places have a lower average max temp than inland places, but because they are east they can also have very high temps. Meaning it’s easier for a east coast place to reach heat wave criteria. If std dev was used, the high range of temps along east coast would be taken into account.


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I think you've answered your own question. Its more marketing and publicity tool than a scientific one.
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Re: General January Weather

Unread post by Razor »

Metservice projecting 35 for Christchurch on Sunday... fire risk is going to be off the charts. I see FENZ are actually issuing warnings via media to be careful about where you go...

https://www.odt.co.nz/star-news/star-di ... ans-warned
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Re: General January Weather

Unread post by TonyT »

Razor wrote: Thu 30/01/2020 10:29 Metservice projecting 35 for Christchurch on Sunday... fire risk is going to be off the charts. I see FENZ are actually issuing warnings via media to be careful about where you go...

https://www.odt.co.nz/star-news/star-di ... ans-warned
A lot is going to depend on the cloud cover. Latest prog suggests thick high cloud in the morning will clear mid afternoon. The time of that clearance (and whether it happens at all) will make the crucial difference between 30 and 35 or higher.

Also, some rain looks to be on the way for Canterbury on Tuesday - model estimates are varying widely with each run and between models from 2mm to 32mm. Thunderstorms possible in the afternoon perhaps?
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Re: General February Weather

Unread post by Chris W »

35C for Chch on Monday as well, now on the Metservice site.
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Re: General February Weather

Unread post by TonyT »

Now looking like clear skies all day Sunday for eastern Canterbury, so 35 plus definitely possible.
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Re: General February Weather

Unread post by Chris W »

My own unofficial guide/rule of thumb on a hot sunny norwester day is that we usually go about 2C over the MS estimate, so I'd say 37 is possible. Not very scientific I know, but just a POV on it. Whatever it is it's going to be hot!

That said, I just checked and they've dropped to 34C, so maybe 36 instead.
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Re: General January Weather

Unread post by David »

Anyone know from memory what is Tauranga's record high temp? Metservice forecasting 33 tomorrow! 8-o

The days with most potential for 30+ here always seem to be too windy. Next 3 days the fresh SWer looks to limit the temps a fair bit
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Re: General February Weather

Unread post by NZ Thunderstorm Soc »

TonyT wrote: Fri 31/01/2020 08:44 Now looking like clear skies all day Sunday for eastern Canterbury, so 35 plus definitely possible.
That's sad :-(
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Re: General February Weather

Unread post by TonyT »

NZ Thunderstorm Soc wrote: Fri 31/01/2020 12:57
TonyT wrote: Fri 31/01/2020 08:44 Now looking like clear skies all day Sunday for eastern Canterbury, so 35 plus definitely possible.
That's sad :-(
I'm not sure I'd call it sad, but its not something I'm looking forward to.

On another note, today's longer range model guidance has pushed back the mid-February trough and colder/wetter period to the start of the fourth week of the month (after the 20th)- sorry Jamie.
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