April 1-23 northern hemisphere temperature anomalies

The recent cold weather seems to have cancelled out the earlier warmth in the month of April, because temperature anomalies up until the 23rd are quite close to average across most of Europe, although Iberia has been unusually warm. The Arctic has been its exceptional mild self once again, and is probably one of the reasons why this recent ‘Arctic blast’ has been so relatively innocuous.

Figure 1

Will the BBC graphics look like this?

One of my readers after reading my article about NWP Web viewers has kindly pointed me to one that the MeteoGroup are trialling at the moment. It’s called MeteoEarth and it’s very ‘Google Earth’ like with a spinning globe, although you can display ‘flat’ maps. There are a number of basic overlays available, but they are just that quite basic, and the contoured pressure overlay does need further work to look right. It might be early days for their web application, because that’s what it really is, perhaps this is some kind of test bed. They seem to be encouraging people to embed MeteoEarth into their own websites, and you can also hook up to social media through various buttons. It makes me wonder if it resembles in any way the graphics engine that they are planning to use when they take over the BBC contract very shortly.

Figure 1 – Courtesy of MeteoGroup

The info box makes interesting reading as well…

Figure 2 – Courtesy of MeteoGroup

They are making use of global ECMWF data in the MeteoEarth, wouldn’t that be a turn up if they did the same thing at the BBC! I can’t see this happening somehow, especially the political ramifications of using European NWP data in preference to Met Office NWP data when, we are just about to begin the Brexit negotiations.

Storm catalogue 1871-2017

Figure 1 – Courtesy of the Spectator

Now that I’ve parsed and run an objective LWT analysis on the six hourly 20th century reanalysis data from NOAA, I can finally start putting some graphs together on what I’ve found. The gale index [GI] is a good place to start, and gives you a quick overview of how stormy it’s been over the British Isles in the last 145 years. Of course the calculation for the GI is for a fixed location 55° north and 5° west, so it has to be used with caution. The way round this would be to adjust the position of the grid, and generate the GI for other grid points, but for the moment GI values from a single point will have to suffice.

Figure 2

Without a doubt, the 1990’s was the windiest in the last 145 years, and it could be that 1990 was the windiest year looking at the graph of the total days when the GI>=30, approximately gale force 8 (fig 2). The winter of 1989-1990 was very stormy and of course that was the year of the Burns day storm. The best fit curve seems to be suggesting the number of gale force days per year has fallen since a little since then, it’s obviously only a rough guide, and the figures for the incomplete year of 2017 will be playing some part in that decline.

Figure 3

If you just examine all the six hourly charts in which the GI>=50 you get a slightly different picture (fig 3). The number of storms seems to have started to increase again since the peak in the 1990’s, and it looks like the stormiest year using the GI>=50 as a threshold was 2014. This finding corresponds well with what the Met Office said about the storminess of the winter at the time in a report entitled The Recent Storms and Floods in the UK so I must be on the right track (fig 3).

Figure 4 – Record of the number of stations reporting wind gusts in excess of 60 kts during December (Courtesy of the Met Office)

What the experts are saying about increased storminess

I’ve scoured the internet to find what climate scientists are saying about any increased storminess in recent years, with little success. I did find a PDF from Rob Allen of the Met Office about storminess from 2006 – Impacts of climate change on storminess – in which he said:-

Efforts are underway in the Hadley Centre at the Met Office to extend the 3-hourly pressure change analysis back to 1920 over the UK, while the potential exists to investigate whether very long-term pressure data series with coarser 12-hourly resolution at about 6 locations in the UK back into the 18th-19th century can provide a truly centennial scale picture of severe storm nature and changes.

I can’t say that I’ve seen any fruits from the efforts that the Hadley Centre were planning to make, but then again the wheels do tend to grind exceedingly slowly at the Hadley Centre, they are still under the illusion that climate data about frost only started in 1961, and temperature and rainfall in 1910. Perhaps I should point them at the masses of reanalysis data that I’ve downloaded from NOAA. It might only be on a 2° x 2° MSLP grid but at least the Americans encourage people to access the climate data that they produce.

If you have access to the Weather Magazine, there is an article about the subject – Historic storms of the northeast Atlantic since circa 1700: a brief review of recent research (Volume 69, Issue 5, May 2014, Pages: 121–125), in fact it mentions just how valuable the reanalysis approach might be in investigating changes in storminess.

Global warming and increased storminess

According to the Spectator in February 2014, Met Office scientists were privately furious with Professor (now Dame) Julia Slingo when she said that there was a link between global warming and recent storminess and the jet stream getting stuck. Professor Mat Collins of Exeter University was quoted in the Daily Mail as saying that:-

‘There is no evidence that global warming can cause the jet stream to get stuck in the way it has this winter. If this is due to climate change, it is outside our knowledge.’

The magazine claimed that Dame Julia had been hung out to dry by the Met Office because of these claims, one can only wonder about if there was a grain of truth in it, because by November 2016 she had been replaced by Stephen Belcher as Chief Scientist. Did she jump or was she pushed, or maybe she just thought sod it I’ve just had another £30,000 bonus, I’m 65 and I’m off.

There was a response to clarify what Mat Collins had actually said in the Met Office blog, which produced dozens of comments from people who totally disagreed with them. I must live a sheltered life because I never noticed all these shenanigans going on the time, and have only just noticed that Dame Julia had retired.

I’ll be back to revisit this reanalysis data when I’ve done a bit more development work…

Cold spell gone before it started

I have a theory that northerlies don’t last as long as they did in the past, the general life expectancy of one is probably no more than 48 hours tops. The cold from the current ‘Arctic blast’, has already moved south to allow warmer temperatures to come down from of all places the Arctic. It’s not evident until you run a comparison of temperatures differences that are 24 hours apart that you’re ever likely to notice it though (fig 1). I’m not saying that temperatures aren’t several degrees below average for this time of year, but it’s warmer 2 or 3°C warmer than it was at the same time yesterday over much of the north, and conversely it’s up to 7°C colder across many central  and southern areas.

Figure 1

This one is a polar low

The earlier low that’s now scooted off down the east coast of Scotland may not have been a proper polar low, but as I suspected might happen, the one that’s just south of Sule Skerry at 1600 UTC is. Figure 1 is not from a kindergarten by the way, it’s my attempt to draw up the 1600 UTC chart using my Wacom tablet, so excuse the state of the isolines, it’s very difficult to get any kind of smoothness or get your hand inside a radius to draw a curved isobar, but it’s the best I can do under the circumstances!

Figure 1

The circulation around the feature is clearly seen in this 1545 UTC visible satellite image (fig 2) with curl of cloud marking the associated trough that lies to the west of the polar low and stretches north-northwest from Stornoway.

Figure 2

If this wasn’t a polar low the next one could be…

Figure 1

The small low pressure in the Moray Firth at the moment (fig 1) doesn’t quite fit the bill as a classic polar low according to my old copy of the Meteorological Glossary. It describes a polar-air depression as:

A SECONDARY DEPRESSION of a non-frontal character which forms, more especially in winter, within an apparently homogeneous polar AIR MASS; near the British Isles the development is usually within a northerly or north-westerly airstream. The chief characteristics of this type of depression, which seldom becomes intense, are a movement in accordance with the direction of the general current in which the depression forms, and the development of a belt of precipitation near the depression centre and along a trough line which often forms on the side farther from the parent depression where also the pressure gradient (and surface winds) is increased.

Meteorological Glossary (6th edition 1991) Courtesy of the Met Office ©Crown Copyright

In this morning’s visible satellite image (fig 2) the trough, which the Met Office have as a wrap round occlusion in their midnight analysis, would usually occur on the western side of the low in this situation, or so says the glossary, but not with this feature looking at the imagery and the weather radar (fig 3).

Figure 2

Figure 3

The precipitation is of snow across the north of Scotland down to quite low levels this morning, and warnings have been issued by the Met Office (fig 3). I hadn’t notice that the Met Office had finally updated the dreadful mapping that they use in their warnings, a lot smarter, but about time.

Figure 4 – Courtesy of the Met Office

Although this low might not be classed as a classic polar low, a proper one might be developing off the coast of eastern Iceland, because the latest pressure falls at Torshavn (fig 5), indicate either a trough or maybe even a proper polar low might be squeezing itself into the tight northerly flow and head southward later today (fig 6), so you never know.

Figure 5 (the wind directions maybe spurious at times)

Figure 6 – Courtesy of OGIMET

BBC weather takeover imminent

The takeover of the BBC weather contract by MeteoGroup must be imminent if it’s to happen this spring as promised. I’ve read recently that Meteogroup are going to provide the graphics for the new service, and I wonder if they are of the same standard that they push out on their Twitter account. It seems that the Met Office are using all forms of social media including Twitter to show of their new graphics engine – Visual Cortex. If these couple of examples I have included from their respective Twitter accounts are anything to go by (figs 1 & 2), I think I much prefer the graphics and animations from the Met Office than those of MeteoGroup, which do look a little dated. Corporately, I think that the Met Office are still smarting after being dropped by the BBC, it’s quite obvious from how they’ve upped their game in the last couple of years on social media.

Figure 1 – Courtesy of MeteoGroup

Figure 2 – Courtesy of the Met Office

Of course MeteoGroup could surprise us, and have their own new bespoke graphics engine ready to go from the start, or maybe getting that in place and tweaked has delayed the takeover. It seems that all the various staffing changes concerning the presenters in London have now taken place, and all we are waiting for now is the big switchover.

SC at 5000 feet

Figure 1

At first I thought that this was low AC when I first saw it, which shows you what a poor observer of cloud I was in my day, but the LCBR at Exeter airport reckons the base is 5,000 feet, and I’m not going to argue with that. Feel free to tag on some extra supplementary varieties to the description such as undulatus, perlucidus (gaps between), or stratiformis.

Dry spell continues

The dry theme that started in late March continues into the last week of April, especially over central southern parts of England (where some stations are still in a state of partial drought), as this graph of precipitation illustrates from Benson in Oxfordshire since the start of this year (fig 1).

Figure 1

A big part of why it’s been so dry is the anticyclonic weather of the past month, as you can see from the Benson barograph (fig 2).

Figure 2

A state of type is now well under way, with cold air set to flood south across the country in a N or AN, but according to the latest NWP guidance that meridional type looks like it will be a relatively short-lived affair, before things become more mobile from Sunday, putting an end to the dry spell even across southern counties.