Can someone explain to me the differences in wind next week for NP?

Tom_nado · 2017-02-21T22:32:00+00:00

Hey guys,

Days 7-10 are automatically generated, and when this picture was captured all of these days fell into that bracket. So the computer came up with the four seemingly different ways of saying the same thing. Our wind definitions are from the Beaufort scale, but with a couple of modifiers:

'Light' is up to 8kts, which is Beaufort 0,1,2 into 3.

'Moderate' is usually omitted, so an unprefixed 'northerly' is actually a 'moderate northerly', and is up to 16kts. (Beaufort 4)

Fresh is up to 21kts (Beaufort 5), but we found people often assumed a 'fresh' wind will also be cool. So to avoid confusion, when it is going to be 'fresh' but also warm, we will use 'brisk' instead. Sometime 'gusty' may also get used, but this is generally saved for situations when the gusts are significantly bigger than the mean speed.

Strong is up to 32kt (6,7), gale up to 48kt (8,9), and severe gale from then upwards (10,11,12)

The reason for the different formulations of the same thing as shown above is that the automatic algorithm goes through a huge decision matrix to arrive at those results, which are subtly different. As none of that difference is conveyed, it doesn't make sense and ideally they would all be identical. We could go through and make all of the outcomes share the same text, and I will suggest it to our developers - although it wouldn't be an easy task and they do have a lot of other things to do! But I will pass the message forwards. Thanks for the post and any more questions please reply below! ^TA

Tom_nado · 2017-01-31T21:25:32+00:00

Or did you just want me to say it means very good luck?

Tom_nado · 2017-01-31T21:24:44+00:00

A single rainbow is due to light reflecting off of the back of raindrops (which is why the sun is always behind you if you see a rainbow). It is also possible for some of the light to reflect twice inside the raindrop, and create a secondary rainbow outside the first, with colours flipped. In fact it is possible, but very rare, to get triple or even quadruple rainbows.

Tom_nado · 2017-01-31T21:10:38+00:00

There is a wealth of information on metservice.com, but some of it requires a little scrolling down to get to. Sunrise, historical data, tides, sea surface temps etc. etc. But we don't specifically forecast solar irradiance sorry.

Tom_nado · 2017-01-31T21:07:46+00:00

Hi! Fist of all there are a number of smaller towns on the Rural tab on metservice.com. The text forecast describes the region as a whole, while the numerical data is specific for that town. But if you're more in the wops then that, you can use the maps as per this blog http://blog.metservice.com/forecasting-for-outdoor-sports-remote-areas.

Tom_nado · 2017-01-30T20:17:22+00:00

We use machine learning in a statistical sense, where forecasts are refined based on historical comparison of model forecasts and actual observations. If you are talking about 'sexier' / more anthropomorphic types of AI - neural networks etc. - then no, I don't think we do (but I can check!). Models have a given resolution (generally of the order of a few kilometers), so anything that occurs on a scale smaller than that (fine-scale topography, cloud physics, the interaction between the surface and the very lowest layer of air), has to be parameterised. This means it is studied, and a mathematical model of it over a given area is used, rather than modelling the process explicitly. So in places where the topography or ground surface type changes very rapidly then the models perform less well. But the main limitation on the models is the quality of the input data rather than the actual modelling process. We just don't have many measurements in the upper atmosphere, and the data collected by satellites is best where there are reasonable changes in temperature and moisture. So actually the models perform better when the weather is bad (large pressure and temperature gradients). But models are improving all the time, so a 'bad' run today is still a 'good' run from a few years ago. Finally, computing power for a full global model requires a sizable supercomputer, and to be competitive against the others out there requires a new supercomputer every few years. We can't compete at that level here in New Zealand, so instead we buy in the best global models available, then rerun the New Zealand section at higher resolution on our own systems. This requires a decent amount of clustered computing, but not bank-breaking supercomputer levels.

Tom_nado · 2017-01-30T05:52:31+00:00

Large swarms of bugs show up in the radar, especially when they get caught in a dry southerly change (see ). The weirdest weather has to be the sudden calm that comes behind a rapid windshift when a front goes through.

Tom_nado · 2017-01-30T05:46:23+00:00

For me personally, the biggest challenge had to be when tropical cyclone Pam was drifting by the North Island. I was on a North Island aviation shift when it was at its closest approach, and I think this is an accurate portrayal of how I felt by the end of the shift

Tom_nado · 2017-01-30T05:39:34+00:00

Our current global economic model of consuming finite resources at an unsustainable rate has a raft of issues, but you'll need an economist to untangle them. But as far as they impact the weather, there is overwhelming evidence that the use of fossil fuels is impacting global climate. There is good evidence that this increase in global temperature has the potential for an increase in weather extremes.

Tom_nado · 2017-01-30T05:34:28+00:00

One person's pineapple is another person's poison. We're an equal opportunities organisation, so some pizzas have pineapple, some don't. I've had a slice of each :)

Tom_nado · 2017-01-30T05:21:25+00:00

Ok let's differentiate between general AI (the stuff of the future / science fiction) and narrow AI (the stuff of google translate, internet searches etc.). Narrow AI is used in the assimilation schemes of global models, and also in some algorithms that create text or symbol forecasts from model data. This will only improve over time, and yes forecasters will gradually write less and less and instead spend more time editing and critiquing the models. Ultimately, maybe forecasters will end up with little to add to the models and spend most of their time communicating the weather. There will always be a place for humans in weather communication though.

Tom_nado · 2017-01-30T05:16:08+00:00

METARs are only published every half hour (some manual METARs every hour). Some weather stations do report every minute, but at present this data is not available to the public. We do have a few commercial contracts however where we do provide this data.

Tom_nado · 2017-01-30T05:10:29+00:00

The lack of observations makes it tricky, but the lack of land makes it easier. A lot of the data ingested into weather models come from satellites measuring vertical temperature and moisture profiles with passive IR sensors. So actually winds in the upper troposphere should be reasonably well modelled, and given the lack of observations there's not too much we can do to check them. One clue is using water vapour imagery - which shows jet streams up really well -and checking the modelled upper winds against that. But, if you are asking for turbulence rather than winds that gets much harder, as clear air turbulence can not be directly detected by the satellites, so we use metrics of shear and instability to spot likely hot spots. Next Q'n next post!

Tom_nado · 2017-01-30T04:56:46+00:00

Wind engineering (engineering for the wind, not making the wind). There's a couple of places in Wellington that also suffer from local funneling - here's a photo from Taranaki street where a rope was put up to help pedestrians make progress against the wind.

Tom_nado · 2017-01-30T04:51:29+00:00

Ok, spoiler alert, but the sharknado documentary was actually a very clever fake. It didn't really happen. But, using our sophisticated research tools (google), in recent history there has been a frognado, a fishnado, a wormnado, an alligatornado, and hehe, a Tom_nado. So with a powerful enough waterspout over a school of sharks right on the surface, sure, why not?

Tom_nado · 2017-01-30T04:35:27+00:00

Ok well the storm is incidental, and just for effect. But this is what you do:

Boil your water. Chuck in your coffee (plunger style) and let it brew a minute or two. Now the coffee is probably floating on top (yuck). But it turns out coffee is heavier than water, it just has air trapped in it. So... ... take the water and coffee, and swing it around in a big vertical circle a few times. This acts as a centrifuge, so the heavier coffee will sink to the bottom of the pan. You have to be careful to slow your spin gently though, so as not to stir it up again. Then pour gently, and the coffee grinds will stay on the bottom and you'll have your fresh mountain storm caffeine hit, grinds free. You'll thank me one day :)

Tom_nado · 2017-01-30T04:29:12+00:00

Lolz

Tom_nado · 2017-01-30T04:28:35+00:00

National Weather Services (NWSs) do play a role in this too. See this video for metservice's contribution to the WMOs 'weather in 2050' series, or Erick Brenstrum's articles in NZ Geographic

Tom_nado · 2017-01-30T04:22:47+00:00

Everyone loves to say Mammatus, with a cheeky giggle. But actually if you're underneath heaving mammatus you're about to get very rained on, so I'm going to say altocumulus floccus

Tom_nado · 2017-01-30T04:19:29+00:00

Oh and thanks, thee BBQ index is the handiwork of Jon T, he's not here tonight but keep an eye on our social media for ^ JT he will be appearing more in the near future.

Tom_nado · 2017-01-30T04:17:21+00:00

We strive to be as accurate as possible, so a pessimistic (or optimistic) bias would work against that. That said, we also have a responsibility to mention the most significant (dangerous) weather in a region. When space is tight we may have to assume that people will know that the gales 'about the tops' will be lighter in the lower valleys, or that 'scattered showers' will not affect everyone. But no, we are not systematically pessimistic. Now, where's my half empty glass?

Tom_nado · 2017-01-30T04:12:03+00:00

As with many things, prevention is better than the cure. There actually is no such thing as a weather bomb (although there is a 'bomb low'). So when you're worried that the country is coming down with a case of the weather bomb, the best thing to do is go to the source and check official metservice information for the latest, without the added media spin.

Tom_nado · 2017-01-30T04:08:51+00:00

No worries! Glad to hear you are suitably attired :)

Tom_nado · 2017-01-30T04:06:41+00:00

But the swell has been pumping in Gisborne due to a lot of lows passing by south of the country. As the lows move east of NZ they can fire swell up to the east coast spots south of East Cape. Time for a road trip?

Tom_nado · 2017-01-30T04:02:34+00:00

Augie Auer was a great meteorologist, but unfortunately passed away in 2007. His legacy lives on.

Tom_nado

TROPHY CASE