Tomorrow’s low

Figure 1 – GFS (1) ECMWF (2) UKMO (3)

It’s interesting to see how the three main NWP models handle tomorrows low and the heavy rain it introduces across the country (fig 1). The Met Office take the main thrust of the rain north into Ireland, whilst the GFS and the ECMWF are in no doubt that the action will be centred much further east over southwest Wales. I think the UKMO model looks out of step with the other models on this one, time will tell.

One of the tricks of the trade as a weather presenter when you want to be as vague as possible about the timing of rainfall events like this, is to leave of the exact time in the graphics, so it’s good to see that Aidan McGivern has picked this one up and is now ready to move on to the next chapter (fig 2).

Figure 2 – BBC (1) Met Office (2)

As well as this cyclonic development on Friday another low threatens to spoil the weather in the southeast of England during Sunday. It’s amazing just how the weather likes to dish out bad weather in as fair a manner as possible isn’t it?

Quiet start to US tornado season

Figure 1 – Courtesy of NOAA

Although tornadoes can occur in any month of the year the ‘tornado season’ is usually thought of as being the months of March through to June, that’s when there’s a greater chance of cooler continental air meeting humid warmer air from the Gulf of Mexico, and hence a much greater chance of thunderstorm development. So far 2018 has been a remarkably quiet year for tornado activity across the United States (fig 1). In fact it could be that April 2018 has one of the lowest tornado counts on record (fig 2).

Figure 2

Here’s a news item from Matt Taylor of the BBC weather team about the slow start to the tornado season in the United States that spurred me into action (fig 2).

Figure 2 – Courtesy of the BBC

The overnight thunderstorms

Figure 1 – Courtesy of Blitzortung

Here are a few graphics to show the extent of this early thundery spell across the country, the severity and extent of which caught both the ECMWF and the UKMO NWP models out yesterday. As far as I can see most of the lightning was from unstable medium level cloud rather than the more traditional cumulonimbus (fig 1). The rainfall from the thunderstorms looks to have been concentrated in a swathe SSW-NNE through Hampshire, where my estimates from weather radar suggest that as much as 32-40 mm fell in the wettest areas (fig 2).

Figure 2
Figure 3 – None of the rain gauges where in the right places, where was Southampton Weather Centre when you needed it?

I won’t go on about just how poor or late the warnings were for yesterdays thunderstorms from the Met Office, or just how divorced the NWP graphics used by either themselves or the BBC was from reality, the following screen shots will have to suffice (fig 4).

Figure 4 – Courtesy of the Met Office (1&2), Blitzortung (3) and the BBC (4).

“Just some of these western coasts may stay a little murky…”

Image 1 – Courtesy of the BBC (upper) and the Met Office (lower)

The ECMWF model being used for the BBC forecast by MeteoGroup is not really handling the sea fog that’s rolling into west of Cornwall and along the north coast of Devon too well this morning (fig 1). The UKMO model has at least captured something in the way of cloud across the southwest, what exactly it is in looking at the graphics is a little bit harder to work out, is it cirrus, or stratus or just sea fog? Alex Deakin doesn’t seem overly concerned about it though, he says that’ll it be “just some of these western coasts that may stay a little murky”.

Figure 2

I’ve been watching this fog and low stratus as it rolls in across the southwest and it’s moving quite smartly to say there’s very little gradient (fig 2). I just wonder how much further east it will progress during the rest of the day as well as how far inland it’ll make it.

Addendum
Figure 3 – Courtesy of the BBC

In the national forecast just after the main BBC news the graphics looked very similar to the ones used during the morning, but in the regional forecast at 1.40 pm it appeared as if they had updated the model which gave a much more realistic fit with the satellite image (fig 3). Ben Rich was too busy demonstrating how proficient he is with the count-up method (you know the one – “temperatures reaching 24 or 25 quite widely, and maybe even a 26 or 27 and possibly a 28 or 29 in one or two spots”) to even be bothered to show any detail of low cloud in the southwest.

The BBC weather website

Figure 1 – Courtesy of the BBC

I hadn’t noticed the recent changes to the mapping used in the forecasts on the BBC website introduced by MeteoGroup, so I was rather surprised to find just how good a ECMWF viewer it was (fig 1). All they need to do now is add some extra layers such as 300 hPa winds and 1000-850 hPa partial thicknesses, and they’ll have a winner on their hands! The NWP only extends to T+168 but that’s fine, the only thing I can really find fault with is that they still use the same dreadful location labels they do in their TV graphics (fig 2).

Figure 2 – Courtesy of the BBC

Even at full zoom there are some rather curious omissions in the towns and cities that they choose to include in their coverage of the UK. Here are just a few of the holes that I spotted across northern England I would have thought could do with plugging (fig 3). I’m sure they’ll put the reason down to keeping the map decluttered, but that could easily be achieved by giving each location a plotting priority, and removing the solid black rectangle they use to overlay each location name on.

Figure 3 – Courtesy of the BBC

Nowcasting and the problem of forecasting low cloud

All sorts of problems in forecasting the exact position and the extent of low cloud across the country this morning. This is nothing new of course and must be the bane of most NWP models in slack situations like this. Both the UKMO and the ECMWF models (if that’s the one MeteoGroup are currently  using) have a poor grasp of low cloud at 09 UTC as you can see by this mornings visible satellite image, and don’t forget these graphics are probably from the 06 UTC model run so the forecast’s are no more than three hours in the future (fig 1). In the 1980’s the word nowcasting was coined to describe these short-term forecasts, but it looks like low cloud in situations like this are proving difficult to keep track of.

Figure 1 – Met Office forecast – Visible Satellite – BBC forecast

You may have noticed that I’m fixated at the moment in examining and comparing the forecast output from the UKMO and the ECMWF models, by grabbing screen shots of the MeteoGroup forecast on BBC 1, and the Met Office video forecast from their website. Why do I do this? Perhaps it’s out of sheer frustration, knowing that although we indirectly pay for both of these institutions, we see output from either model in any detail except by snatching screen shots. I’m so glad that MeteoGroup did win the BBC contract because it does help in highlighting the differences and shortcomings of both models.

A lot of hot air over next weeks warmth

Figure 1 – Courtesy of the BBC

Yes it’s official, it looks likely that Thursday and Friday of next week may well be on the warm side for April (fig 2). But there’s nothing unusual about warm days in Spring, and someone should tell the media to cool down and not get so excited (fig 1), because after all spring did spring over six weeks ago according to their definition.

Figure 2 – Courtesy of www.wxcharts.eu

The hype you get these days from the NWP soothsayers is getting to almost biblical proportions. In the winter they are the same people who’ll tell you with great delight that the cold snap that hasn’t even started yet, will only last a couple of days. Well two can play at that game, because it saddens me to report that it looks likely that this weeks warmth may also be fleeting!

Met Office make it three in a row

Figure 1 Courtesy of  BBC/ITV/Actual

The Met Office make it three in a row, with an 8-5 win over Meteogroup on today’s maximum temperatures. On the strength of the last three days the ECMWF seem to over-estimate afternoon temperatures, although I still can’t manage to get them to agree on when to report them in either of their forecast graphics. Today I had to use the ITV graphics for the Met Office forecast because the Met Office are so darn quick at deleting any evidence in their early morning forecast. I’m going to have to find a better way that this to verify their forecasts…

Today’s poor forecasts

It’s difficult to pin these two organisations down when it comes to verifying just how accurate their maximum temperature forecasts are. But the Met Office model is already one up after yesterday, so I thought I’d just see how they did today.

Figure 1 – Courtesy of the BBC and the Met Office

Here are the actual temperatures at 1600 BST today which I mark 76% to the Met Office. The forecast for London was really dreadful from both models, obviously they expected the stratus to clear but it didn’t. I can’t understand why MeteoGroup have labels for both Glasgow and Edinburgh, but only one temperature, and for which city it’s for. If anything MeteoGroup should have had the edge because the actual and forecast temperatures are both for 1600 BST, but that didn’t stop the Met Office taking a two nil lead.

It wasn’t only temperature that caught out both the Met Office and MeteoGroup today, there was also an area of heavy rainfall that extended across Humberside into Yorkshire during the afternoon that escaped both models. I watched the rolling news on the BBC news during the afternoon and I think even worse than the poor forecast was that the presenter never seemed to noticed that it was happening at all, let alone bothering mention it or show a real-time weather radar image. It reminded me of the taped forecast given by Michael Fish as the Boscastle flash floods was in progress in 2004. I can’t see why the Met Office have bothered to update their weather radar network when no one seems to look at it. Here’s the BBC forecast for the east Midland’s from yesterday evening (fig 2).

Figure 2 – Courtesy of the BBC

MeteoGroup v Met Office

I’ll fully admit before I start that a inter-comparison between the ECMWF based forecast presentation from MeteoGroup and that of the Met Office’s with their own model data on a day of reasonably benign weather like today is a little bit over the top.

Figure 1 – Courtesy of the BBC

The ECMWF model does have a finger of showers running down the east coast but Simon King doesn’t (or forgets) to mention them in this particular broadcast at 12 am, even though he’s under no obvious time pressure (fig 1). The MeteoGroup graphics showed little or no low cloud across the southeast of England, which prompted him to say “a bit of cloud feeding into central areas, but either side of that we’ll continue with the sunshine into the afternoon” (fig 2). So nothings changed with the presenters, they believe the NWP in the graphics rather than check the latest observations, weather radar and visible satellite image. It’s as much the presenters fault as it is MeteoGroup and they now all work for the BBC and not them.

Figure 2
Figure 3 – Courtesy of the Met Office

In the forecast video on the Met Office web site, Aidan McGivern does mention the showers which seem to be more obvious on the Met Office model, but then puts his foot right in it by adding that classic cliché ‘high pressure in charge’ (fig 3).

Figure 4

This visible image reveals how the BBC graphics have underdone the amount of low cloud across the southeast, the Met Office seem to have done better in its distribution (fig 4).

Figure 5

As for the light showers that are aligned along the weak cold front, both models have underplayed them, the Met Office seem to have made slightly more of them (fig 5).

In the forecast for this lunchtime, I think the Met office and their model did enough to just edged it over the BBC. Next time I do an inter-comparison between the two, I’ll have to choose a day with a bit more weather.