Scotland looking grand

With most people’s eyes firmly fixed on storm Angus today – including me – we have almost forgotten what a grand day it was further north. Here’s a high-resolution visible satellite image of Scotland taken earlier today to prove it.

2016-11-20_1007_metopb_21662-fc-corrected-crop

Images courtesy of David J Taylor

Angus – the warnings

2016-11-19_161427

Courtesy of the Met Office

With the wind warning they issued yesterday, the Met Office didn’t quite make the 70-80 mph gusts on mainland UK as far as I can see. The highest gusts that I’ve seen from the SYNOP reports are from this morning’s gale at Langdon Bay in Kent of 59 knots (68 mph) and from experience of last years named storms, the threshold for amber is a gust of 70 mph (60 knots) or more as far as I know. I’ve ignored the 73 knot gust on Guernsey by the way, because for some strange reason (and I may be wrong) I don’t think that counts because the Channel Islands aren’t technically part of the UK. But I’m sure that the Press office at the Met Office have been frantically scurrying around this morning, so that shortly we will find that there was a gust to 75 mph on the Needles and everything will be fine. But as far as I am concerned even though it was a windy night for a while on land, and even though there was a severe gale running in the channel (force 12 at time) – null points.

Rain is another matter, they definitely were on the right track here, with a forecast of 20 to 30 mm and locally 40 mm. There was indeed a large area of 20-30 mm as you can see in my rainfall analysis for Angus, but the locally 40 mm should have read 60 mm or possibly a little higher. So they slightly underestimated the extreme rainfall totals but pretty good otherwise.

 

Angus – the forecast

I am still putting together an application to verify the NWP models that are available on the Internet. Namely the GFS, ECMWF and the UKMO models. I try to download the images from Wetterzentrale each day – my eternal thanks to the German guy behind that site! I am not really interested in short-term forecasts of T+72 or earlier , but in the medium range of T+96 to T+144 where things can go a little awry. And that’s how it was with Angus at T+120. Have a look at the following three solutions that were issued on the 15th of November for midnight last night (20 November), ignore the CPTEC model which is basically unstable, unstable being the technical term for crap.

2016-11-20_102159

Here’s the analysis from midnight that I use to verify the forecasts – ignore the [T+120] in the title that’s something else that needs fixing.

2016-11-20_102423

Here’s my analysis of the three models:-

  • GFS – The position is just a little too far northeast by around 1°. The minimum pressure is around +8 hPa too high and that makes Angus not quite intense enough.
  • ECMWF – The position is just too far northwest of where Angus was at midnight maybe by 1.5° in both latitude and longitude. The intensity looks just about right as I make Angus around 967 hPa at 00z.
  • UKMO – The position is too far north by around 3°. It almost looks like there is a double centre which elongates the forecast low when it really was very circular affair. The intensity was around +8 hPa too high making the center way too flabby.

The Met Office would like you to believe that forecast for 5 days ahead are as accurate as the forecasts for 2 days ahead of 20 years ago. Well on the strength of this comparison, I would say we still have some way to go. Like the Curates egg, some models are better than others, and if I had to rank the forecasts made on the 15th for last night, then I might give first place to the ECMWF model, which just nudged out the GFS model with a more accurate intensity, even though the forecast position was a little off. The Met Office came in third, which might be the reason why they prevaricated so much all last week about just how much impact this low would bring to the UK, and whether they should give it a name – who knows.

Angus – the wind

I may be running this analysis a little bit too early because I’ve just noticed that the strongest winds from Angus maybe occurring right now (09Z) in the southern North sea but what the hell, I’m sure my 19 subscribers won’t mind in the slightest.

wind-analysis-1000-utc-on-19-november-0900-utc-on-20-november-2016And if you don’t like maps here it is in ranked and tabulated :

tabulated-wind-analysis-1000-utc-on-19-november-0900-utc-on-20-november-2016So, from what I can see there has been no inland gales (on low ground) apart from Culdrose which is a little set back from the coast. The Channel Isles took a bit of a battering with a mean speed of 46 knots (53 mph) and a gust to 73 knots (84 mph) at Guernsey airport at 03Z. The real core of the high winds though with Angus ran down the entire length of the English Channel. The three weather buoys in the eastern channel give an idea of the strength of the winds with a gust of 92 knots (106 mph) at 62170 at 09z, and a mean speed of 65 knots (75 mph and hurricane force 12) at 62305 at 07z.

The above list is not definitive by any means, as the Met Office have access to many other weather stations that I’m not privy to. These values are probably enough to justify the warnings that the Met Office issued yesterday morning, if not, I’m sure that they will be using values from the Needles in their defence as they so often do.

Angus – the rain

estimated-rainfall-accumulations-1800-0845-utc-on-sun-20-november-2016

I never realised just how much overnight rain we had received in our part of Devon until I generated the estimates from the weather radar and was surprised to find that Exeter airport was the top of my list of estimated totals for SYNOP observing sites with 48.8 mm. When I plotted the actual 18-06Z totals from the SYNOP observations I realised that I had underdone that a little bit because the 18-06Z total from their SYNOP was 58 mm (2.28 inches). As you can see there was a broad area of totals greater than 16 mm. Inside that there are large areas of 24-32 mm and some purple pixels indicating totals  greater than 50 mm mainly across north Devon, the Malverns (at a guess) and the North Downs south of London. Don’t forget these are just totals for 12 hours, so an inch or even two inches or more of rain in that length of time means a spell of very intense heavy rain.

Here are the observed totals on a map:

rainfall-mm-0600-utc-on-sun-20-nov-2016

And these are the totals in a ranked table:

rainfall-mm-0600-utc-on-sunday-20-november-2016-in-wmo-block-03-highest-rainfall-mm

Going back to my estimate for Exeter airport here is more of a close up of the estimates:

estimated-rainfall-accumulations-1800-0845-utc-on-sun-20-november-2016Here in Bradninch (8 km to the north of the airport) my trusty Vantage Pro tells me that we had over 40 mm overnight with a period of at least 15 minutes around 0100 UTC when rainfall rates were around 60 mm per hour. This coincides to when Angus was passing to the south, and as you can see from the plotted grid nearby Dunkeswell had four hours of continuous heavy rain between 23 and 02Z.

synop-grid-03840-dunkeswell

Angus – the track

The forecast that John Hammond gave on Thursday about the likely track of storm Angus and the extent of the gale force winds was quite good, the only thing they forgot to do was give it a name! But to be a little more pinnikity Angus did take more of a northeasterly track across southern England than was anticipated.

img_2802

But because the Met Office tie impacts to the naming of storms, they had to wait to less than 12 hours before it arrived to Christen it. I suppose that’s the only way they can do it, but to be honest Angus still will have only affected a small proportion of the UK by area and there are still vivid memories of what October 1987 brought in this part of the country. The gales as anticipated have been mostly confined to southern coastal areas, in mid-channel there have been winds of up to force ten at a quick glance, which is not untypical of any winter month in the British Isles.

synops-0000-utc-on-sun-20-nov-2016

The low at times exhibited a very tight centre. Have a look at the 03Z observation of 965.5 hPa which looks like the minimum pressure for Angus, which produced a massive pressure gradient but maximum cyclonic curvature.

synops-0300-utc-on-sun-20-nov-2016

Almost hurricane like, Angus as soon as it makes landfall starts to fill and head northeastward to East Anglia.

synops-0600-utc-on-sun-20-nov-2016

 

It’s official – it’s not Angus!

2016-11-18_120505

Courtesy of the Met Office

The Met Office have finally made a decision about the fate of this weekends vigorous low which is set to bring 20-30 mm of rain and a southwesterly gale to the southeast of the country. They feel that both these factors don’t add up to a significant enough impact for the low to be Christened Angus the “one”.

I get the feeling that unlike last year when they gave names to any number of extratropical cyclones that brushed up against the northwest of the country, this year they seem more reluctant to name any low that’s not forecast to be less than 960 hPa and impact an entire country, in fact it’s a bit like the time before that “name-that-storm” came along when names just seemed to spring out of the ether in retrospect.

The Chief Forecaster has left a get out clause embedded at the end of the warning, or should that be a get out paragraph: “There remains some uncertainty about the exact track of the weather system and therefore the northward extent of any impacts” – we will see.

2016-11-18_120303

Courtesy of the Met Office

Just to remind you what a real storm looks like, here’s a plotted chart of Katie from the 28th March 2016. This weekend storm is forecast to take a similar track to that of Katie, which was of the few named storms that did make landfall last season.

synops-0400-utc-on-mon-28-mar-2016

Here’s this morning’s forecast chart from the Met Office:

ppvi89

Courtesy of the Met Office

Worst of the winds in the channel – shades of 1987?

Courtesy of the BBC

I’ve already blogged this morning about how the Met Office seem to be prevaricating about what will happen with this weekend’s low pressure. Well the prevarication is over and they’ve just announced – courtesy of John Hammond in the 12.57 PM BBC forecast – that the strongest of the winds will stay in the English channel – well probably!

According to the Met Office the strongest winds should be here…

img_2802

Courtesy of the BBC

Or less likely they could be here…

img_2804

Courtesy of the BBC

It’s a bit like the old joke “I used to indecisive, but now I’m not so sure”. You can’t help but draw parallels with the situation on the 15th of October 1987 and on Sunday the 20th of November 2016 (I always said there was 29 year cycle), when Michael Fish just a few hours before the storm broke, issued these wonderful immortal words: “Earlier on today, apparently, a woman rang the BBC and said she heard there was a hurricane on the way… well, if you’re watching, don’t worry, there isn’t!“. That evening as most of you will know the worst storm to hit the southeast of England for many years caused record damage and killed 19 people. Forgive me as soon as I see charts with arrows on I can’t help  but think of Dad’s Army!

hqdefault

Courtesy of the BBC

And because named storms depend on having what they call multiple “impacts”, this looks like it won’t be a named storm either by the looks of things.  It does make you wonder since they are about to lose the BBC contract just how the Met Office in the future will get these kind of pontifications across to the general public – twitter, Facebook the ITV?

Below is the latest T+72 forecast chart from the ECMWF. Frustratingly they only produces images for the whole of Europe and the North Atlantic and just in 24 hour time steps – come on get real – Brexit has not officially started, and we still pay for this service and we can’t even zoom into different regions of Europe. Having got that off my chest – that chart does seem to support that the strongest gradient will run over northern France, so maybe they’ll be right – time will tell.

2016-11-17_132247

Courtesy of ECMWF

Met Office prevaricating?

2016-11-17_120053

Courtesy of Google

It seems to me that the Met Office are doing a lot of prevaricating about the low that’s forecast to cross the country this weekend. I’ve already looked at the output from the three major NWP models and there does seems to be a divergence in how the UKMO model plays it when compared to other models, and exactly where the low will track and how much it will intensify is crucial. I suppose to be fair it’s still only around 60 hours away, but I imagine they are still very undecided in which way to play it, especially when it seems to be gunning for the southeast of England! At 1210 PM on Thursday there’s still been no news on if this will indeed be storm Angus, and still no warnings have been issued for this weekend.

2016-11-17_121053

Courtesy of the Met Office

If I were the Chief and looking at the T+84 for 12Z on Sunday, I would be naming that storm pretty sharpish, especially when you remember some of the lightweight affairs that they named as storms last season.

2016-11-17_121238

Courtesy of the Met Office

Surely this is Angus?

I know that I’ve been twittering on about when the first named storm will arrive since the start of October, but at last there seems to be some consensus amongst the top three NWP models about the deep depression that’s due to show its hands later this weekend.

  • GFS – Has the would be Angus over north Devon and further east than the other two models at ~ 975 hPa
  • ECMWF – Has the would be Angus in the Celtic Sea and a lot more potent ~ 967 hPa
  • UKMO – Has the would be Angus as a much flabbier affair (and on the strength of this maybe not a named storm) around Dublin ~ 975 hPa.
  • CPTEC* – There are obviously problems with the T+120 frame of this run.

2016-11-15_112256

It will interesting to see just who performs best of the three models at T+120 and if this low will get them twitching in Met Éireann and Exeter over the next few days.

* I’m not altogether sure what the CPTEC model is that I download from Wetterzentrale. The best reference I can find to it on the internet, reveals that it’s a Brazilian NWP model from the Centro de Previsão de Tempo e Estudos Climáticos, hence the CPTEC acronym.  That rather grand bit of Portuguese by the way translates to the more mundane ‘Centre for Weather Forecasting and Climate Studies’. Anyway, there model looks way out of step for T+120 when compared to the three big players, namely the GFS, ECMWF and the UKMO.