The house that Jack built

This is the purpose-designed house that Jack built.

This is the Cray XC40 supercomputer that cost £97 million, has 1.6 petabytes of memory and runs over 16 trillion calculations per second that sits in the purpose-designed house that Jack built

This is the sophisticated NWP model, that runs on the Cray XC40 supercomputer, that sits in the purpose-built house that Jack built

This is the last night’s forecast produced by the sophisticated NWP model, that runs on the supercomputer, that sits in the purpose-built house that Jack built.

These are the actual temperatures for 04 UTC close to the house that Jack built.

In my reworking of the old nursery rhyme, Jack is of course synonymous with the Met Office, if you’ve not already guessed! What I’m trying to say I suppose is this:

You may have the fastest and the most accurate forecast model in the world, but if you can’t visualise what the model is telling you, then you may be just wasting your time.

These NWP  models generate so much highly detailed forecast data, a lot of which forecasters can’t possibly assimilate, and getting the salient facts about the weather across to the public, such as the overnight minimum temperatures seems to elude them. Compare the forecast temperatures in the graphic from the BBC with the actual temperatures at 04 UTC this morning, and you will notice that they are around 3°C too high in most of Devon. It makes no difference that the Cray XC40 supercomputer is located just 2.26 km to the west of the airport, and even though the mesoscale output from the model may have correctly forecast the temperature at 04 UTC, the BBC graphics are still wrong.

Some may argue that the temperature that the BBC show are for “towns and cities”, but that to me is just a clever get out on their part. There is a problem forecasting extreme temperatures, especially overnight minimum temperatures which has never successfully been resolved, in fact I would say that little effort has ever been expended either by the Met Office, or the company that provides the BBC graphics in doing so. Let’s hope that Meteogroup, in these days of 4K television, come up with an improved way of displaying extreme temperatures which more accurately reflects what the model is  forecasting when they finally take over the service next March.

Ex-tropical storm Rina holds up cold front clearance on Saturday

Figure 1 – Data courtesy of the NHC (approximate GFS positions from the 00 UTC 10 November model run)

I wondered what was holding up the cold front clearance on Saturday across southwestern parts of England (fig 2), but then I noticed on the Berlin Meteorological Institutes website, that the second shallow low the follows behind the low that tracks WNW- ESE across Ireland, Wales and the southeast of England during Saturday morning, was labeled ex-tropical storm Rina (fig 1). The Met Office of course are having none of that because it wouldn’t be correct would it.

Figure 2

Will Rina be the finale of the Atlantic hurricane season?

The last advisory on Rina highlighted what had been yet another rather unusual tropical cyclone in 2017 (fig 3):

Figure 3 – Courtesy of the NHC

Rina lives on in Europe

Interestingly, that rather shallow low which was Rina was when it crosses the UK is forecast to develop into quite a deep low of 991 hPa by 12 UTC on Sunday, as it tracks southeast across the Alps into the northern Adriatic, and quite a significant feature in that part of Europe (fig 4).

Figure 4 – Courtesy of the Met Office

Yellow Warning for rain?

Even more interestingly, so far the Met Office haven’t issued any yellow warnings for heavy rain in southwestern parts during Saturday. I just wondered if the tropical origins of the air might even enhance the rainfall in theses parts.

Something for the weekend

Figure 1

The latest run of the GFS model (fig 1) has sided with the UKMO model (fig 2) and decided not intensify the low that runs across Central England on Saturday. It still looks a thoroughly wet day though, especially across the west of Wales and the southwest of England though, with a westerly gale along the English Channel, if this latest forecast is correct (fig 1). Sunday looks a windy day with strong northwesterly winds particularly down the east coast of England and Scotland, with wintry showers down to quite low levels in the northeast of Scotland I would fancy.

Figure 2 – Courtesy of the Met Office.

I wonder if the enhanced troughing in the GFS solution will be justified, the Met Office have little troughing on the cold front in their solution.

Graphics speak with forked tongue Kemosabe

Figure 1 – Courtesy of the BBC

There are numerous problems that I see with this approach to forecasting the overnight minimum temperature that David Braine uses quite regularly in the weather forecast on BBC southwest, and last night’s forecast he gave was a case in point (fig 1):

  • The colour contoured temperatures are invariably at odds with the individual spot values.
  • You never know the exact location of any of the spot values, for instance is the 8 for Sennen or the 1 for Sherborne?
  • Are the temperatures from two separate models, and why are they usually so different and misleading?
  • I know that we live on a peninsula down here in the southwest, but why are 6 out of the 8 spot values at coastal site?

I have a theory that the colour contours show the minimum temperature for the overnight period, and the spot values are the forecast temperature, in this case for 05 UTC even though the minimum will occur close to dawn. If what I believe is the case the solution looks simple.

  • Never combine the extreme colour contoured temperatures for a period with spot values for a fixed time.
  • Instead of using spot values for a fixed time pick out temperatures for towns and cities from the colour contoured value.
  • Use slightly higher resolution data and finer contours to highlight the differences between valleys and moorland. In Anticyclonic situations the valleys will be much colder that the hills.
  • Zoom in a lot more, and pan from west to east, at least 75% of the area in the forecast for the southwest is the open sea!

Here for the record are last nights minimum temperatures from 1800 to 0600 UTC (fig 2).

Figure 2

Firming up the forecast for Saturday

Figure 1

The forecast for Saturday is starting to firm up now with the latest T+84 products from the UKMO and the GFS. The tightest gradient at 12 UTC on Saturday look to be across south Wales and the Southwest, all though truth be said, it looks a pretty stormy affair anywhere south of 54° north across the British Isles, as the low itself tracks across central Ireland and across the Irish Sea, exiting across the southeast coast of Scotland by midnight.

By the time Dietrich; as I think it will be called by the Berlin Meteorological Institute; reaches the British Isles on Saturday it’s already a well occluded low, because it peaks as early as Friday at 20° west in the central Atlantic, when its central pressure is much lower at 960 hPa. So I suppose if the cyclogenesis took place later than forecast it could arrive in an even more angry mood than this forecast. Don’t you just love the British weather?

And please rest assured as Darren Bett has just reminded us

This IS NOT a hurricane!

Ophelia at T+36

Figure 1 – Courtesy of Wikipedia

This is the only decent visible satellite image that I can find from yesterday of Ophelia as category 3 Hurricane (fig 1). The Met Office of course remain aloof from all the fuss about Ophelia, acting like they don’t have any access at all to high quality satellite imagery, because why on earth would anyone be interested?

What a perfect combination the UKMO and EUMETSAT, just throw in the WMO and you have the perfect triumvirate of ineptitude.

Why is it that I can view any of these types of satellite images or movie loops for the Caribbean, Gulf of Mexico and Western Atlantic courtesy of the Americans:

  • Visible
  • IR
  • IR AVN
  • IR Dvorak
  • IR enhanced
  • IR JSL
  • IR RGB
  • IR Funktop
  • IR rainbow
  • Water vapour

But as soon as a hurricane gets any further east than 35° west, we immediately revert to the dark ages. It would be nice to think that Brexit would change all of this, but it’s for certain that the Met Office will sail on into the sunset oblivious to it all as if nothing really matters.

Figure 2 – Courtesy of Intellicast

Ophelia passed to the south and the east of the Azores overnight as a category 2 hurricane. She is racing northeast at 30 knots, and is expected to turn more north-northeast today (fig 2), because if she doesn’t then watch out Bognor!

Figure 3

There’s a remarkable degree of similarity between the T+36 forecasts from the GFS and UKMO models for 12 UTC on Monday this morning (fig 3). The centre of Ophelia is slightly (~1°) further northeast in the GFS solution than the UKMO, this is probably to do with a slightly faster solution rather than a difference in track I would have thought. The centre of Ophelia is at 972 hPa in the GFS and down at 965 hPa in the UKMO, this may be due to the OGIMET contouring or the resolution of the GFS model they are using, I’m sure the Met Office track the centre of vortices in their models, rather than rely on a fixed grid of MSLP values as the GFS does. The isobars are very tight around the centre of Ophelia, which does mean that you would have to reduce the geostrophic wind quite a bit because of the tight curvature of Ophelia to get the true gradient.

No change in the warnings, either from Met Éireann or the Met Office this morning, although I would expect that they will be tweaked by Exeter this morning,. No mention yet of a yellow warning for heavy rain yet either, although Ophelia is moving through very quickly, the models do indicate a shield of heavy rain lying to the west and northwest of the centre.

The irony of this event occurring 30 years after the ‘great’ storm, is that unlike 1987, the southeast are best placed to get away with quite a warm breezy day, with little in the way of rain compared to places further west and north.

Ophelia now the sixth major hurricane and heading northeast at 20 knots

The latest midday run puts Southwest England in the firing line for a spell of south southwesterly gale force nine winds from ex-hurricane Ophelia by midday on Monday. As well as running Ophelia further east and up the west coast of Ireland, the run is also that bit quicker, then again, I make the centre closer to 975 than 970 hPa, but still with a small intense centre, so reminiscent of a tropical cyclone that she was until a few hours before (fig 1).

Figure 2

I’ve just FTP’d the UKMO T+48 fax chart from NOAA to see what the boys in Exeter make of it, and I must say that they’ve managed to make the gradient look a lot less threatening across the southwest than in the GFS. I’ll be interested to see what they come up with tomorrow morning when they issue their strong wind warnings.

Figure 2 – Courtesy of the Met Office

Meanwhile the NHC have declared that Ophelia is now a category 3 hurricane, and the 6th major hurricane of the season, they also add that:

Ophelia is a quite intense and rare hurricane for its location in the northeastern Atlantic

The maximum sustained winds are now 115 mph, and her central pressure is 960 hPa, and more importantly she is his racing northeast at 20 knots directly towards southwest Ireland. If I were the Chief forecaster on the Sunday night shift, I would be getting slightly twitchy as dawn breaks on the 16th.

Figure 3 – Courtesy of the NHC

Ophelia and the latest GFS run

Figure 1

Looking at the last two runs of the GFS for the specific time of 12 UTC on Monday, its noticeable that the T+60 version is just a little faster and brings Ophelia a couple of degrees closer into SW Ireland (fig 1). It’s difficult to count the very tight gradient around the centre of Ophelia, but it looks to be around 970 hPa which is similar to the UKMO T+72 forecast solution for the same time.

Figure 2 – Courtesy of the UKMO

The incredible shrinking warning

Thursday  – the warning for heavy rain and strong wind looked like this…

Figure 1 – Courtesy of the Met Office

By Friday they had shrunk it a bit…

Figure 2 – Courtesy of the Met Office

And on Saturday they cancelled it denying all rumours that it had ever been issued!

Figure 3 – Courtesy of the Met Office

Apologies for missing this story yesterday, I was busy programming, and because rather oddly the Met Office don’t alert you when they cancel a warning I managed to miss it. I must say that this is the first time that I’ve ever seen a warning cancelled, modified in some way yes, but never cancelled. This warning was peculiar from the start, the area in my opinion was particularly odd in the way that stretched northwards towards Perthshire. The cancelled warning was also unique because as far as I could see, it was the first ever ‘dual’ yellow warning that shared the same area for wind and rain I’d ever seen.

It’s a bit of a climb down for them after all the fuss they made about heavy rain on Sunday, and now it’s been cancelled due to lack of rain! It’s not good news for their model at 3 and 4 days out either, what was it thinking, Lee and Maria were obviously misbehaving, or perhaps the Chief forecaster was just too quick in pushing a warning out four days before it was going to happen?

The latest observations and rainfall accumulations for this Sunday up untill 08 UTC indicate that they did make the correct decision, although the Northwest highlands which weren’t in the warning area are seeing plenty of heavy rain at the moment from the warm front.

My GFS prediction that Monday would be wetter across the southwest could still come off, looking at the latest run of the GFS, and against all the odds ex-hurricane Maria has kept her circulation going for much longer than had been forecast during the last week (fig 4).

Figure 4

The old 50 to 60 with gusts to 70 mph ploy

As Inspector Clouseau might say to Kato “So it’s the old 50 to 60 with gusts to 70 mph ploy“, well in the strange and bizarre world that I inhabit he well might.

So the Met Office are playing it cool when it comes to renaming low Wolfgang storm Brian. I wonder if they will revisit their yellow warning again tomorrow just to fine tune it some more? Here’s a screenshot of the yellow warning and the latest thinking from the Chief, just for posterity of course (fig 1).

Figure 1 – Courtesy of the Met Office

I also notice that unlike the GFS model, the latest forecast on the BBC for Monday keeps the low further south, and makes very little of either the low or the rain.

Figure 2 – Courtesy of the Met Office