10 February 2018 – heavy rain over Northern Ireland

Figure 1 – Courtesy of the Met Office

The Met Office may have purposely forgotten to issue a strong wind warning for Philine yesterday, but the NWP model must have been indicating some heavy rain for Northern Ireland so they did issue a yellow warning of heavy rain for the province (fig 2). As you can see there was indeed some intense heavy rain, with rainfall rates of over 32 mm per hour at 1810 UTC (fig 1) close to where low Philine was developing a discrete centre. This shows you just how good the NWP models can be.

Figure 2 – Courtesy of the Met Office

Weather Radar Estimates

As far as I can see from my estimates from weather radar images there was a largish area with totals in excess of 50 mm for the period 10-1200 to 11-0845 (fig 3).

Figure 3 
Evidence from the rainfall gauge
Figure 4

It’s clear from the gauge network totals for the 24 hours ending 06 UTC (fig 4) that the weather radar may have been over doing the intensity of yesterday rain for some reason. The freezing level was low enough for the rain to be falling as snow down to low levels ~2500 feet, so the white intensities (fig 1) could have been some form of bright banding effect.

The warning itself was just about perfect for Northern Ireland, but there were even higher totals across northwest England and southwest Scotland that didn’t get a mention.

Do gusts of over 50 mph require a yellow warning?

Figure 1

The Met Office issued a whole tranche of yellow warnings for heavy rain, snow and ice for the overnight period, as low Philine whizzed across the borders, but neglected to issue one for strong wind. This is getting a bit of habit with them now. I wonder just how high a gust has to reach before one is issued, obviously higher than the 79 mph at Capel Curig at 22 UTC yesterday evening (fig 1). They did go to town on snow and ice warnings, even one for ice down here in the southwest after the front cleared, although they never really amounted to a hill of beans. The warning for heavy rain was a horse of a different colour – but more of that later. As you can see my idiom output is set to maximum at the moment.

The new look BBC weather forecast and attribution

Figure 1 – courtesy of the BBC

This is how the new BBC weather service opens now that MeteoGroup have taken up the contract (fig 1). In the many hundreds of articles that I have written for this blog, I always try my best to attribute the source of any of the data, images or maps that I use out of common courtesy. So why is it that the BBC can’t do the same thing? They don’t seem to mind doing it with the shipping forecast on Radio Four:-

“This is the shipping forecast issued by the Met Office, on behalf of the Maritime and Coastguard Agency, at 0505 today, Saturday the 10th of February 2018…”

So why don’t the BBC do the same thing in the national weather forecast? We know that warnings will continue to be issued by the Met Office, but are just left guessing about the source of model data MeteoGroup are using in their TV forecasts.

Why is it so important?

The reason it is important that we know, is that in the future an unexpected weather event occur may occur that was much more severe than was forecast, and blame will be apportioned. Because in the past it was always easy to lay that blame at the feet of the Met Office, it’s now a lot more complicated. It’s not the fault of the presenters because they are employed by the BBC and are really just the messengers, it really lies with MeteoGroup choice of forecast model with which they produce that poor forecast with. So knowing where that forecast data came from is important, because as far as I know MeteoGroup have full access to forecast data from a number of different sources, including the American (GFS), European (ECMWF), and the UKMO models.

Credit where credit’s due

The solution is simple, in the opening credits the BBC should indicate which model data MeteoGroup have used to produce that particular forecast with – credit where credit’s due (figs 2 & 3). Who knows MeteoGroup could pick and choose from day-to-day which model they favour, and if they don’t choose to use the UKMO model it’s not inconceivable that the forecast data is out of synch with any warnings issued by the Met Office.

Figure 2 – courtesy of the BBC
Figure 3 – courtesy of the BBC

Saturday night’s low

Figure 1 – Courtesy of www.wxcharts.eu

I wonder if Met Éireann will end up naming the low that runs across Northern Ireland later on Saturday? It looks like the Met Office are more concerned about the snow from it over SE Scotland and NE England. This low is not hanging about though, so I can’t see that being a big problem. The latest GFS run does have the low undergoing rapid cyclogenesis, deepening by 30 hPa by the time we get to 06 UTC on Sunday morning (fig 1), and more markedly than do the UKMO in their latest forecast charts (fig 2).

UKMO Chief Forecaster’s assessment

Rain and hill snow, accompanied by some strong winds, is expected through Saturday evening, clearing eastwards overnight. Above around 200 metres, 2-5 cm of snow may accumulate although there is a small chance of 5-10 cm falling over the Southern Uplands. As skies clear from the west overnight into Sunday morning, ice is expected to form on any untreated surfaces“.

Figure 2 – Courtesy of the Met Office

Georgina adds to the growing list of forgettable storms…

How many named storms can you remember? It’s a simple enough question and the scheme has been running for three years now so you should at least remember a couple. I can’t, but then again I’ve a dreadful memory, but you would have thought after writing an analysis on all twenty-three of them as I’ve done, I would have remembered  at least one.

Storm Georgina although it deepened explosively was just another failure in my opinion, another storm to forget, and again it was named by Met Éireann. Full marks to the Met Office for staying clear of this one. Met Éireann seem to be specialising in naming just about anything that comes their way at the moment, I suppose someone has to name them, and I’m sure if it hadn’t been them the French or maybe the Norwegians would have stepped in to do the honours.

Here’s an analysis of the top twenty or so peak gust from storm Georgina of Beaufort force 10 or higher, storm force gusts are an essential requirement of any reputable storm in my opinion, plus of course the obligatory vortex (fig 1).

Figure 1

The highest gust from a low-level land station was one to 85 mph at Benbecula on South Uist, the highest at all stations in WMO block #03 was the gust to 117 mph at the Bealach Na Ba on the road to Applecross in Wester Ross (fig 2). Interestingly the maximum gust across the Irish Republic was just 65 mph at Belmullet.

Figure 2
So much for storm naming – what about the warning?

I found it odd that there was just a single yellow warning issued for storm Georgina by the Met Office, and that covered just the Northwest of Scotland. Although the warning of gusts 50-60 occasionally 70-80 was very precise (as long as you weren’t driving to Applecross) the area of extent was far too limited. No warning were issued for the rest of Scotland, England or Wales, even though there have been gusts today of 83 mph at places such as Capel Curig and 70 mph on Emley Moor.

What difference is there for example, between the gust of 62 mph at Stornoway, in the yellow warning area, and the gust of 64 mph at Farnborough and not in the yellow warnings area? The chances of a slate being blown of a roof would be similar, but the difference in population would make the chances of it happening far greater at Farnborough.

In the table (fig 1) I’ve highlighted the stations that weren’t covered by the yellow warning, and as you can see they form the greater proportion of places that had storm force gusts. I don’t know, and can’t understand why a yellow warning wasn’t issued yesterday, when the GFS model correctly forecast peak gusts of 55 to 65 mph and occasionally higher for today. The Met Office needs to find some consistency in the thresholds they use in issuing warnings for strong wind, because I can’t see any logic in how they do it at the moment.

Storm Georgina – the Irish beat the Met Office to it again

Figure 1 – Courtesy of the Met Office

Met Éireann have now named low Helene (as it was formerly known) storm Georgina, if that makes any sense (fig 1). The Met Office seem convinced that the yellow warning that they have in place will suffice, even though the GFS model is predicting severe gale force gusts across England and Wales ahead of the cold front tomorrow morning.

All I can say is that they must be supremely confident that their NWP model (not that we can see any output from it) has got this nailed on the head, and that the current yellow warning they have in place are sufficient – time will tell.

More explosive deepening and severe gales

Figure 1 – Courtesy of www.wxcharts.eu

The next Atlantic low is poised to run in later today and overnight and introduce gales across the whole country, with gusts to severe or even storm force across the northwest of Scotland. Low ‘Helene’, as the Institute of Meteorology at the Free University of Berlin have called it, will deepen according to the latest GFS model (o6 UTC) by around 29 hPa in 18 hours or so as it tracks across the Isle of Lewis and clips Caithness by 06 UTC tomorrow (fig 1).

The Met Office at the moment have issued a yellow warning for strong wind from 01 to 14 UTC tomorrow for gusts of 60-70 mph with some to 70-80 mph but it’s only for the northwest of Scotland (fig 2).

Figure 2 – Courtesy of the Met Office

The GFS model is forecasting severe gale force gusts ahead of the cold front across the whole of England and Wales later in the night (fig 3). There has been no word on any additional warnings for England and Wales from the Met Office, so I can only assume that the UKMO model is at odds with the GFS, or maybe that the fire at the Met Office this morning on a server, has been more serious than we thought and is somehow hampering them being issued?

Figure 3 – Courtesy of www.wxcharts.eu