General February Weather

[Awhituobs]

We have been getting spits of rain from patchy high cloud...with blue patches...must be a lot of moisture in the upper atmosphere left over from that cyclone
27c here currently with sea breeze

[spwill]

Some thunderstorm cells over inland Otago now. Coastal Otago has been shrouded in mistly low cloud today, the moist air flowing over the cool sea, Dunedin currently 15C, dp 13C.

[Orion]

Earlier this afternoon I saw some potentially interesting cloud-forms to the west, however no sign of the blue and yellow diagonal line that haunts the rain radar.

Gentle south-easterly breeze, high haze, and smoke from local crop-residue burnoffs;

22.1°C, 59% humidity.

[Richard]

I see it made 31.6 back home. Mean while drove through fog or low cloud most of the way, broke away from it halfway to Ranfurly heading up inland, then hit heavy rain and a few flashes. Can't believe how green it is here.

IMG_20200218_173157.jpg

IMG_20200218_174441.jpg

[Richard]

Looking SE.

IMG_20200218_175958.jpg

[Richard]

SE storm has grown huge in short time.

IMG_20200218_180902_BURST004.jpg

[Richard]

Another big system to the south.

IMG_20200218_180911.jpg

[tornado]

i didn't take photos sorry but impressive cloud build ups led to a couple of downpours in south auckland. didnt hit me in takanini though but the clouds were the blackest i seen this year with lines of rain all the way to the ground


Looking forward to saturdays front. but not too excited yet. 50 percent chance we get a decent fall from this front. 50 percent chance just drizzle due to high pressure being either side of it

[Storm Struck]

Finally a slight reprieve up here with heavy rain this morning, eased to lighter drizzly showers this afternoon.
Still warm on 22C and 90% humidity, 19mm recorded at the airport.
Might be enough to open some reserves, which will please a lot of mountain bikers and trail users.
We still need a swag load more rain though, and we are back to 25C tomorrow.

[tgsnoopy]

I wish they would fix that glitch on the radar that points to the SW from the radar itself at Rakaia.
It's infuriating

It's not a 'glitch', but rather interference from an external source, i.e. someone illegally transmitting on the same frequency. See: https://blog.metservice.com/Radar_Interference

Yes, the interfering transmissions are illegal, not saying they aren't.

However, you need to consider where in the spectrum the MetService Dual Polarity Doppler Radars are. They (MetService Radars) are licensed services, in the middle of the normally free for all international 5.8 GHz band used for WiFi, linking etc. Suppliers in NZ are not required to, and therefore don't point out that the equipment (5.8 GHz TCPIP links, video senders, WiFi etc) should be configured to prevent interference in certain areas of NZ. It is noted in the GURL, but who reads that?

Many many people transmit there with no idea they are breaking the law and causing interference. I've bought it to the attention of quite a few in my patch & got them to move. RSM's Radio Inspectors are too thin on the ground & too busy to actively police this. It takes MetService to have consistent interference & complain to get them to even consider looking for interference. I suspect they set up masks to hide quite a bit of the interference, this would definitely degrade the performance.

Ok, lets look at the GURL:

https://gazette.govt.nz/notice/id/2015-go2276

Can you see anything warning you to avoid the frequencies the Radar uses?

Next look at this leaflet:

https://www.rsm.govt.nz/assets/Uploads/ ... update.pdf

Quote: "You should be aware that ground weather radar, covering channels 114, 118, 120, 122, 124, 126 and 128, operates at nine locations across New Zealand. These being Kaeo, Tamahunga, Mamaku, New Plymouth airport, Mahia, Outlook Hill (Wellington), Rakaia Trig, Blue Spur Range (Hokitika) and Invercargill Airport. If 5GHz Wi-Fi equipment is to be deployed in the vicinity of these 9 locations, it is highly recommended that these channels be avoided, as the weather radar is licenced for protection from interference. If your equipment causes any problems to these licenced services, compliance action may be taken against you."

It's not that obvious and no wonder the interference is an ongoing problem.

[Happy Feet]

I've been working on this speadsheet for a while, wanting to put this dry into historical context. Sorry, I know Waikato is not the only region affected by this dry, but it's where I'm at, and Ruakura research station is one of the better long term records we have in the country.

https://drive.google.com/file/d/1RNcU0l ... sp=sharing

Alarming how many of the lowest Jan+Feb+March totals have occurred since 2008.
This year must be odds on at this stage to go straight to number 1 for the driest Jan plus Feb total. Really hope it does not however.

Your spreadsheet is really interesting. I would like to know how much of the variability in the Jan + Feb combined totals is due to occurrence or absence of ex-tropical storms. I don't suppose the data is available to check that.

[NZ Thunderstorm Soc]

Cloudy this morning with low cloud cover going away from noon.
Fine but hazy day with NE and a maximum of 24.4C
Some cu forms but nothing eventuating with lower cloud returning this evening.
Some pictures this afternoon.

[Chris Raine]

A gloomy day here today with persistent 8/8ths SC after this mornings shower. No idea except by looking at Metservice radar and Blizortung that thunderstorms were happening around Gore .Temp mid 20's and humid

[David]

As of this morning my 60 day rainfall total is now down to 9mm, quite incredible really.

[NZstorm]

The front on Saturday looks to be a narrow band of convective rainfall. There could be some upper level divergence off the jet with it which would ensure we get some rain.

Today the convergence zone is Northland down to Coromandel, so Auckland out of the heavy shower risk.

[Awhituobs]

got woken at 5am by rain on the roof
0.8mm
lol
(first rain in 35 days here..water tank nearly empty)

[Orion]

Foggy here at present; 14.3°C; 73% humidity.

[Richard]

A lovely sunny day coming up in Central Otago, light northerly

[Chris W]

The front on Saturday looks to be a narrow band of convective rainfall. There could be some upper level divergence off the jet with it which would ensure we get some rain.

Today the convergence zone is Northland down to Coromandel, so Auckland out of the heavy shower risk.

Looks less narrow down here, chance for a few mm of rain to at least wet the soil. Maybe storms inland as the upper air is cold (-20C to -25C) and it's a southeast change by the looks.

[TonyT]

Looks less narrow down here, chance for a few mm of rain to at least wet the soil. Maybe storms inland as the upper air is cold (-20C to -25C) and it's a southeast change by the looks.

I would rate good potential for storms across Canterbury on Saturday.A half-decent rainfall event for some perhaps. Maybe some hail for Christchurch?

[Chris W]

Yeah, UKMO model (metservice 5-day rain map) liking 20-30mm widespread right up to Marlborough. Would be amazing.

Not sure I can fix the rotation, sorry.

20200219_115636.jpg

20200219_115641.jpg

[BeaconHill]

I had a go at averaging the data "by decade" to see if there was a trend evident from that. Used data from 1920's onwards (as full data set for those years).

Have plotted the Jan-Feb, and Jan-Mar Averages

Ave By Decade.png

Incl Yearly.png

Certainly a downward trend occurring.

EDIT: Added an additional graph showing the average Annual rainfall trend (when viewed by decade averages). And Mr Excel indicates a trend of 8.3mm less per decade on average.

I've been working on this speadsheet for a while, wanting to put this dry into historical context. Sorry, I know Waikato is not the only region affected by this dry, but it's where I'm at, and Ruakura research station is one of the better long term records we have in the country.

https://drive.google.com/file/d/1RNcU0l ... sp=sharing

Alarming how many of the lowest Jan+Feb+March totals have occurred since 2008.
This year must be odds on at this stage to go straight to number 1 for the driest Jan plus Feb total. Really hope it does not however.

[Awhituobs]

good work!

[TonyT]

I had a go at averaging the data "by decade" to see if there was a trend evident from that. Used data from 1920's onwards (as full data set for those years).

Have plotted the Jan-Feb, and Jan-Mar Averages

Ave By Decade.png Incl Yearly.png

Certainly a downward trend occurring.

EDIT: Added an additional graph showing the average Annual rainfall trend (when viewed by decade averages). And Mr Excel indicates a trend of 8.3mm less per decade on average.

I've been working on this speadsheet for a while, wanting to put this dry into historical context. Sorry, I know Waikato is not the only region affected by this dry, but it's where I'm at, and Ruakura research station is one of the better long term records we have in the country.

https://drive.google.com/file/d/1RNcU0l ... sp=sharing

Alarming how many of the lowest Jan+Feb+March totals have occurred since 2008.
This year must be odds on at this stage to go straight to number 1 for the driest Jan plus Feb total. Really hope it does not however.

Sorry to say, but you'd struggle to get any meaningful statistical significance out of those graphs. It MIGHT be a downward trend, but confidence in concluding that is not high. Whats more interesting I think is that rainfalls in the last 2 decades have been very similar to the 1940s and 1950s.

[Willoughby]

It would be good more locations could be added to see the trends and improve the confidence - then one could generate rainfall trend maps like the BoM do: i.e.: http://www.bom.gov.au/climate/change/in ... iod%3D1920

Do NIWA produce anything like this?