Precision warnings…

I know that the latest super computer and the new model had given the Met Office even greater resolution with their forecasts, but I never realised that it could be relied on to the degree of precision that they claim in the latest warning that they’ve just issued for east Lancashire for tomorrow morning (fig 1). I know than rainfall intensity increases with height, and that there’s a fair bit of high ground in this yellow warning area, but to be so confident to say that heavy won’t cause problems on the M6 motorway, but will further east in a relatively small area around Burnley, seems at best overly confident, and at worst a little reckless. We shall see what transpires, perhaps the accuracy out to T+30 with rainfall intensity is that precise these days.

Figure 1 – Courtesy of the Met Office

It’s interesting to see that the larger Bolton just NW of the larger Manchester population 128,139 is still being labeled on the warnings map, in preference to the smaller Bolton just outside Appleby in Cumbria, population 435.

Regional mountain forecasts from the Met Office

There have been some major improvements made to the regional mountain forecast issued by the Met Office which have just been announced. I’ve just had a quick look at them, and as a retired Munro bagger myself, I think that the website and it’s content are perfect for anyone planning to go hillwalking  and trying to assess just how good or bad weather conditions will be.

Figure 1 – Courtesy of the Met Office

Thankfully, although the webteam use the same map component they use in the severe weather warnings (fig 1), it’s not zoomable, just clickable, and when you do click it you get quite a detailed forecast (fig 2). I imagine that in winter each regional area forecast will also include any warnings regarding avalanche risk. There, who said I couldn’t write anything nice about the Met Office!

Figure 2 – Courtesy of the Met Office

Unusual medium level shower activity…

Figure 1

I’m probably going to shoot myself in the foot with this one, but it looks to me, and I could be wrong, like much of the precipitation that’s been showing up on this afternoon’s weather radar, especially the belt that stretches across central England is from medium level unstable castellanus cloud, and is producing nothing more than the odd shower. There are some brighter echoes within, and the observing network is pretty thin so it could be falling between the gaps, but I see very few reports of any significant rain or thunderstorms from it.

Figure 2

Here’s the latest visible image (fig 3) that shows the band very well.

Figure 3

The rainfall over western Scotland looks even more dramatic, and this is thundery in nature (fig 4), although the rainfall indicated in the weather radar image looks very intense, it also seems to have escaped the observing network so far.

Figure 4 – Courtesy of Blitzortung

Interestingly, the current Met Office warning that is in force for heavy thundery rain this afternoon, completely omits the west and north of Scotland (fig 5)!

Figure 5 – Courtesy of the Met Office

 

Hot spell not going to go quietly…

The latest 06 UTC model run must be showing signs that the breakdown of the current hot spell is not going to be a quiet one.

Figure 1

It looks like the Met Office are still having problems with this new warnings web page of theirs. The map is a great improvement on the old one, but some of the locations plotted on it are blatantly in the wrong place. I reported this to them a couple of weeks ago, and it really should have been fixed by now. At worst its misleading to the general public, at best it just doesn’t look professional, I am amazed that it wasn’t picked up at testing.

How’s this thing going to end?

A good degree of consistency between the UKMO and GFS models about how saturday will look at T+120 (figs 1 & 2). How accurate it will be is another thing entirely. Pressure is still forecast to be reasonably high across the south, 1000-500 hPa thicknesses are not far from 564 dm, but there is a fresh to strong westerly flow across the British Isles, with fronts driving in from the west, so things don’t look good for this current hot spell.

Figure 1

Figure 2

A sense of perspective on the winds from this week’s low

Figure1 – 1615 UTC 6 June 2017 – Courtesy of Met Office & EUMETSAT

I get the feeling from what I’ve read about the strong winds that affected the UK on Monday and Tuesday of this week (5th and 6th of June) that they weren’t considered in anyway severe by most people, but if you step back and look at the daily mean wind speed you will see that the winds were just as strong, or in some cases even stronger than any day in the last six months. Have a look at this chart of mean daily wind speeds for Plymouth (fig 2) to see what I mean, the numbered pink bands represent the four named storms that occurred during this time:

  1. Barbara 20 December 2016 23 – 24 December 2016
  2. Conor 23 December 2016 25 – 26 December 2016
  3. Doris 21 February 2017 23 February 2017
  4. Ewan 25 February 2017 26 February 2017 (Ireland)

Figure 2

Here’s the daily run of winds from Heathrow (fig 3).

Figure 3

Figure 4

And even in the English Channel, as windy a day as any seen throughout the entire winter (fig 5).

Figure 5

So a sustained mean wind speed throughout an entire day in June, can be as high, or even higher than in any of the named storms that occurred in the last Winter. That of course combined with the fact that trees are all now in full leaf, which will increase the chances of impacts from falling trees during the summer months. Here are some events of recent years that occurred in summer across the UK.

Falling trees, or falling branches or boughs from trees kill people each year, and no number of weather warnings of whatever colour will stop tragedies caused by them.

On a lighter note

It’s no wonder that on Tuesday, a tenth of the UK’s power was coming from offshore wind farms, and on Wednesday, which was also breezy and much sunnier, the National Grid reported, that for the first time, over 50% of UK electricity came from renewable electricity. Here’s another take on that news that you might like to read from euanmearns.com.

6 June 2017 – rainfall

Figure 1

It’s the turn of the east coast to take a soaking today, and pretty dreich it’s been down along east coast for much of the day. Wettest place in the list of available observations is Edinburgh with 35 mm in the 12 hours ending 18 UTC (fig 1), I overestimated the total their by around 15% (fig 2), and also managed to underestimate the Weybourne total in Norfolk by a similar margin. Plenty of places on the higher ground of Scotland, Cumbria the North York Moors with rainfall totals well in excess of 50 mm today, which is not bad going in 12 hours.

 

Figure 2

The northwest Highlands seem to have escaped the yellow warning for rain today, as did Gogar Bank with its 35 mm, because it lies outside the yellow alert area just to the west of the city. It looks like eastern Scotland will see a lot more before it’s done.

Figure 3 – Courtesy of the Met Office

Who won the battle of the models?

Here are the two solutions to what the analysis should look like at 00 UTC on Tuesday the 6th of June, made 48 hours before by the GFS and UKMO models. How did they compare with reality?

Figure 1

Figure 2 – Courtesy of the UKMO

For the purposes of this comparison I’ll use the Met Office midnight analysis to compare them against (fig 3).

Figure 3 – Courtesy of the UKMO

Positionally, the UKMO are very slightly closer to the centre of the low on the north coast of Wales, but both models are still a fair way SSE of the true centre. The Met Office intensity of 989 hPa is slightly higher than the 987 hPa it was at midnight, the GFS have it spot on. Shape wise, the Met Office edge it, having a slightly more elongated trough feature than the more rounded GFS solution. I adjudge this a draw, with both models providing good guidance at T+48 hours out. The only question that remains, is why, with a northwesterly gradient like that over the southwest, did they dither about with issuing a yellow warning for strong winds?

Bizarre belated warning from the Met Office

The Met Office never fail to amaze me – they’ve suddenly just realised that the wind has been blowing strong – and have just issued a yellow warning for it valid from 1000 BST today.

Figure 1 – Courtesy of the Met Office

Surely they knew full well that there would be strong winds today so why so late? I would have thought that a strong wind warning, should have been issued at the same time as the ones for heavy rain, i.e. on Sunday morning.

The point about warnings is that they are usually made in advance, and the more in advance the better. This one was issued just a few minutes before it became valid, and reminds me of the warnings that I issued at RAF stations as an assistant for snow that began “The snow now falling…’.

Also, winds of the strength mentioned in this warning – gusts to 40-50 occasionally 60 mphhave been blowing since yesterday morning across much of the southwest of England, so why didn’t that merit a warning yesterday? Here for example (fig 2), are the plotted observations from St Mawgan close to Newquay, where many holiday makers yesterday were getting battered by the wind and the rain sat in their tents and caravans.

Figure 2

It strikes me that the strong wind warning was a sudden afterthought, were someone suddenly realised that they’d completely forgot about wind. I wrote on Sunday half jokingly that they should have named this low Fleur, and I’m now quite convinced that they should have done that. Why did they treat the heavy rain and strong winds that the low would bring separately? They got the forecast right in their NWP, but then proceeded to cock it up with their warnings for rain and wind.

Monday, 5 June 2017 – rain

Figure 1

My estimate for Capel Curig since 06 UTC this morning is very close to 60 mm of rain so far (see inset hyetograph in fig 1). There are also scattered red pixels over Snowdonia, which means totals in excess of 75 mm, to a lesser extent, there have been totals of between 32 and 50 mm over the southern Cumbrian fells, south Wales and southern Dartmoor. Still some more rain to come in the west as the cold front come through during the evening and night.

Looking at the actual 06-18 UTC rainfall reported totals, I see that my estimate for Capel Curig was around 20% too high – well you can’t win ’em all (fig 2). The Plymouth estimate of 17.9 mm was closer, and the Trawsgoed estimate of 20.9 mm was closer still.

Figure 2

As regards this morning’s yellow warning of heavy rain, which runs through till 10 UTC tomorrow, the Chief forecaster said and I quote:

This has the potential to widely generate 40 to 60 mm of rain and as much as 80 mm over some areas of high ground, most likely in Cumbria and Snowdonia.

Well with over 16 hours to go, we’ve already seen those kind of values across those areas of the country.