Low with no name brings strong winds to west

Figure 1

The low that even the Institute of Meteorology at Berlin couldn’t be bothered to name (fig 2) has been producing a spell of strong to gale force winds across the west and north of the UK and Ireland overnight (fig 1).

Figure 2 – Courtesy of the Free University of Berlin

Most of the lows energy from yesterdays explosive cyclogenesis has been dissipated by agitating the central North Atlantic (fig 3).

Figure 3 – Courtesy of the NWS

I notice that wave heights of 12 metres have been recorded at weather buoy ‘Pap’ (fig 4).

Figure 4

Low Carola just misses K1

Figure 1 – Courtesy of NASA

Low Carola came very close to passing directly over the weather buoy K1 this lunchtime by the look of the visible satellite image (fig 1) and the plotted observations (fig 3).

Figure 2

The gradient ahead of Carola was very tight, but it was even tighter behind it, with K1 reporting storm force 10 northwesterlies with a mean speed of 53 knots with gusts to 70 knots at 14 UTC – now that’s what you call a storm!

Figure 3

Hurricane force winds on top of the blue hill

Figure 1

Hurricane force winds on top of Cairngorm this morning, where the winds is meaning 77 knots (113 mph) and gusting to 98 knots (120 mph) at 10 UTC, that’s close to category two hurricane strength, and that’s a ten-minute and not a two-minute mean. The wind has been slowly backing over the last couple of days, and with the air temperature currently at -3.7°C that means a wicked wind chill equivalent of -17.2° for any poor sod who’s daft enough to be up there at the moment.

Figure 2

BBC: Storm Emma smashes boats at Holyhead marina

Figure 1 – Courtesy of the BBC

I completely missed this story about the extensive damage to boats in the marina at Holyhead. There looks to have been around eight hours of gale force eight northeasterly winds at nearby Valley (fig 2). This in itself is not that unusual, but the wind direction never wavered, and it was probably this as much the strength of the wind that compounded the problems at Holyhead. When gales do occur from any run of the mill extratropical cyclone that crosses the country, the wind usually back ahead of the low, and then veer as it moves away, but on Friday the winds never budged and remained northeasterly, the flow trapped between high pressure to the north and low pressure of Emma to the south (fig 4).

Figure 2 – Valley anemograph
Figure 3 – Courtesy of Ordnance Survey & Bing Maps

I’m guessing here because I’m no expert, but although the local orography suggests that Holyhead might have been offered more protection by the island of Anglesey itself, the winds on Friday from 060°, must have been perfectly aligned for the sea that it whipped up in the short fetch across Holyhead Bay, to find its way between the breakwater and the pier at Holyhead (fig 3). A high spring tide of 5.77 metres which occurred at 2008 UTC on Thursday the 1st of March might also been another key factor.

Figure 4

In like a lion…

Figure 1

March has certainly come in like a lion this year, well a lion is a beast after all. Nowhere across the country seems to have escaped the snow and freezing temperatures, and at 09 UTC this morning 49 cm of snow is being reported at St Athan in south Wales and 46 cm at Bishopton, Glasgow (fig 1). From what I can see from the chart almost every SYNOP station is also reporting an hourly gust of 25 knots or more, on another day of fresh to strong easterly winds, and although not as cold as the last two days, it’s still subzero in many places.

I would say at this point that not all SYNOP stations have snow depth sensors, and some that do aren’t reporting a depth at the moment, probably as a result of severe drifting, which could also be affecting the snow depths from the stations that are reporting one!

Spare a thought for the hill sheep farmers and their livestock, they must be going through a particular frigid time at the moment. Just imagine how much snow must have fallen on higher ground and the intense cold if conditions are like this on Great Dun Fell (fig 2).

Figure 2

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.

Just how windy was January 2018?

Figure 1 – Courtesy of the BBC

Last Monday night on BBC Spotlight, David Braine was looking back at January and saying about just how windy it had been in the UK particularly the southwest. David quoted some statistics for average wind speeds for the southwest (fig 1) which got me thinking about just how windy had it been.

Because I’ve been downloading hourly SYNOP observations for the UK for quite a while now I decided to find out how many UK stations had an average mean hourly speed of 15 knots or more during each of the last four January’s, and these are the four tables for each of those months (fig 2).

Figure 2

As you can see from this simple method 2018 was not particularly windy across the UK in general, being overshadowed by January 2015 and 2016. The mean wind from St Mary’s on the Scilly Isles is quite a good sentinel for wind speeds in the southwest. The mean there over the last four January’s has been 20.0, 20.4, 15.4 and 19.9 knots. So I would say that at least in this small survey January 2018 was no windier than usual.

Here’s a chart of the average mean wind speed this January for stations across the southwest (fig 3). What’s puzzling is that none of those stations have a mean speed of 17 knots as David showed in his graphic (fig 1). I’m not sure how he came up with that value, unless of course its some kind of  gridded regional mean wind speed from the Met Office.

Figure 3

The other thing I noticed that also looked a bit odd was the average gust of 27 knots that he quoted (fig 1). In a UK SYNOP report gusts are only reported if the wind speed in any hour has reached 25 knots or more. So the average would always be at least 25 knots, which would make it artificially high if it was made up of reported gusts – what about the hours when the gusts were below 25 knots? I would have thought the only meaningful statistics that you could extract would be the number of gusts that exceeded a specific threshold such as 34 knots, or the absolute highest gust for the month. Again I suppose it may be possible to derive a ‘average gust’ from a gridded dataset for a selected region. It would helpful in the future if the Meteogroup presenter on the BBC displayed a caption of where the climate statistics were for and the source of that information.

5 February 2018 – wind chill at 10 UTC

Figure 1

Lovely morning down here in the southwest, but the wind is adding a bit of a bite to it even so, with a-5.6°C wind chill at nearby Dunkeswell at 10 UTC (fig 1). The SC sheet that’s lying across northern England and Wales seems to be aligned with the lighter winds down the axis of the ridge (fig 2).

Figure 2

There’s talk of a SSW event later in the month, which may explain why the GFS model has been in a total quandary for a while now, with little consistency from run to run beyond T+120.

Winter in Africa

The cold air that’s currently affecting the North of Africa at the moment, is certainly producing some intense convection over the seas that’s resulted in this water-spout just off the coast of Tenerife yesterday. The video is courtesy of Twitter.

Figure 2 – Courtesy of Wikipedia

Up at Izaña on Tenerife at 2,390 metres (7,841 feet) above sea level, winter has the Observatory (fig 1) in its grips at the moment (fig 3).

Figure 3 – Courtesy of Twitter

Here are the observations from the last 24 hours from the Izaña observatory (fig 4).

Figure 4

And here are the temperatures for the last month at Izaña (fig 5).

Figure 5

So it’s no wonder that there was heavy snow in Ouarzazate, Morocco for the first time in 30 years on Sunday (28th January 2018). Thanks to Facebook for this particular video clip.

It certainly seems that there’s a lot greater chance of seeing some snow in North Africa than there is here in mid-Devon. It’s now over eight years since we have seen any snow lying here – what a place to retire to for a professed  snow lover!

24 January 2017 – line convection on cold front

Figure 1

One memorable thing that did come out of storm Georgina, was the line convection that ran southeastward across the country during the morning, it was associated with an active cold front that was aligned SW-NE, from Exeter in the southwest to Hull in the northeast at 09 UTC (fig 1). If you take a look at some of the times of the approximate peak gusts across the country, many of them occurred on the passage of the cold front (fig 2).

Figure 2 – Approximate hour of peak gusts