A rare thing a journalist at the BBC with any meteorological knowledge

I’m being picky again – as is my wont – but the BBC 24 hour news have been running a news item for most of the morning about yesterday’s flooding across the country, and I’ve just found the same article on their website which looks like this:-

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Courtesy of the BBC

In the news item they were implying (and you’ll have to take my word for it) that yesterday’s heavy rain and flooding were caused by Angus, but little did they know or care that Angus has long since departed these waters, in fact at midnight it was approaching Kiruna in Northern Sweden. Yes, I know it’s a technical point and that most members of the general public won’t give a damn, but not for my well-informed readers or the curmudgeonly like me it’s just misleading and not true. It seems like it’s a rare thing to find a journalist at the BBC these days with any meteorological knowledge, perhaps he or she previously worked at the Express and has not had the sensational tendencies knocked out of them yet.

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Angus – the warnings

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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.

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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.

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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

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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:

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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.

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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.

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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.

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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.

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

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Angus set to run along the channel…

Looking at the latest pressure falls on the 2100 UTC chart, Angus looks set to run along the channel, at least till the early hours. Not a great night to be chugging up or down the English channel in a ship I would have thought, but of course they will be.

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The strongest winds at 2100 were confined to the SW of England and the tip on northwest France.

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Pretty wet at the moment from Cornwall through to Dorset.

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Hear are the 0900-2100 UTC estimated rainfall accumulations with St Mary on Scilly the wettest place. To be fair, as soon as the showers gave out down here in Devon today a veil of cirrostratus was thickening up so quickly that the dry interlude didn’t last anytime at all.

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A wild and windy night…

The Met Office say on their blog, that the reason for the low being named Angus is that the event impact have been upgraded to Amber. That’s probably because the low is around 8 hPa lower that they were forecasting previously. If you compare their latest amber warning with the previous yellow one, you will see how they have enlarged the yellow area, and also added an inner amber core to cover the gusts to 80 mph.

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Courtesy of the Met Office

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Courtesy of the Met Office

I have to zoom to 300% to get this kind of detail that you see in the image below. I’ve never noticed this problem before, perhaps it’s my eyesight. I feel that I must be missing something obvious, please drop me a line if you know the secret of getting an image of the warning area that you can actually see!

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Courtesy of the Met Office

If this forecast comes of, storm Angus looks at least or slightly more severe than the low associated with storm Katie did back in March.

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It’s official – it’s not Angus!

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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.

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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.

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

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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…

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Courtesy of the BBC

Or less likely they could be here…

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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!

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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.

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Courtesy of ECMWF