Met Office see a cold start to the winter…

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Courtesy of Met Office

I don’t know why I’m getting carried away with the latest news from the Met Office about a cold start to the beginning of winter 2016/17, but I must admit I am a little. It must be the little boy in me that just wants to see the world turn white, at least for a few days or so, preferably over the Christmas holidays. I love the infographic they use in their long-range forecasting it says very little in effect, but apparently because the QBO is in an easterly phase and totally out of phase, this is expected to weaken the westerlies over the North Atlantic and allow blocked conditions to occur more and hence more winds from the north and east. One thing about the Met Office is it knows how to take advantage of social media in all it’s forms, I can just see them getting warmed up down at the Daily Express at this very moment!

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Courtesy of the Met Office

 

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.

13 September 2016 – Forecast

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I’m forever being left in a position where I could have sworn (and often do) that the BBC forecast for that day is markedly different to the one that I remember from watching on TV from the previous day. This of course is due in part (maybe a large part) to increasing senility, so to get round the problem and lack of evidence (because if you try to find some the next day, you’ll realise that the BBC are remarkably adept at removing any) I always record the weather for the week ahead. The program itself is not easy to catch, but my PVR never seems to miss it.

Anyway the purpose of this article was to examine the BBC forecast for yesterday and see how close the presenters using the best Met Office NWP got to reality. I reckon that the BBC record the program in the evening even though the program doesn’t sometimes go out till the early hours, this particular one aired at 0020 BST. So I reckon that the graphics are from the 1800 UTC model run, and the forecast steps they use to cover the next days weather the T+12 to T+30. So how well did they do on the 13th?

Temperature

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This chart is a clever get out because the BBC forecast never actually display a maximum temperature in a forecast as they did in the old days of magnetic symbols, and which to my mind is just as valuable as any spot value. The graphic above is displaying forecast temperatures for the specific time of 1500 UTC, and if I were to claim that they were underestimating the maximum temperatures in the parts of the southeast by more than 3°C,  the first line of their defence would be is that they’re not the maximum temperatures. But to be quite honest, Nick Miller had started the whole forecast with an introduction about advection and insolation standing in front of a graphic with 31 emblazoned on it, so having become adept and how they employ social media (and a TV forecast is just another form of it) the maximum temperature they were going for was most certainly 31°C. Small point to some, but in my opinion they got caught out in many places in the east and southeast of the country, but they would never admit to it but quickly move on and talk about how tropical storm “Ian” is coming our way.

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Thunderstorms

Not quite getting the maximum temperature correct was quite minor to how they mishandled the thunderstorms in some central and western areas of the country. Here is the picture at 1000 UTC and then the weather radar reality:

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All the activity further east and aligned differently because the activity had nothing to do with old cold front like the NWP seemed to suggest. Let’s move onto 1500 UTC.

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The model has again failed to pick up on all the severe thunderstorms that were tracking north into the west Midlands and heading for Manchester in the early evening. What’s most noticeable from either of these two BBC forecast graphics is the total lack of lightning symbols, but I suppose if the graphics just had scattered light showers there wouldn’t be any. I did hear Nick Miller say at this point in the forecast that there could be a thunderstorms over northeast Wales but that didn’t tally with the graphics.

The day seems to end with the 1500 UTC frame in the ‘Forecast for the week ahead’ forecast, as if nothing ever really happens in the evening, but it did that evening and the severe thunderstorms continued to develop and play havoc with parts of the northwest.

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Severe Weather Warnings

I did check the warnings page at the Met Office last night and to be fair there was an alert one out from mid morning for heavy rain over northern England. But I’m sure there wasn’t an alert out for the thunderstorms and the even heavier rain that affected the west of Cornwall around 1800 and again at 0300 UTC  the next morning. I could be wrong about this, but because there is no archive of alerts and when they are issued (as far as I know) I can’t be 100% certain.

Conclusion

I don’t think the forecast for the next day was accurate either in regard to the exceptional temperatures in the east and southeast, or from missing the thunderstorms and heavy rain in parts of the west and northwest. I watched some of the output for the next day through Twitter, and if that was anything to go by the press team at the BBC seemed to be more focussed on the rising temperatures in the southeast than any thunderstorms that were already occurring in the southwest of the country.