Top up your tan at Tiree – sunnier than Costa del Sol

Figure 1 – The AWS at Tiree courtesy of the Met Office & Ordnance Survey

Tiree is the place to go if you want to top up your tan this month (fig 2). In the first eight days they’ve already got a ton up with 113.2 hours of sunshine, which is a daily average of 14.1 hours, and almost 90% of the maximum possible. Yesterday at Tiree, they cracked the 15 hours of sunshine in a single day mark, and will no doubt do it again today.

Figure 2

Not far behind them are the two sunshine stations in Northern Ireland, followed by Prestwick on the Ayrshire coast (fig 3). I find it amazing how nature always tries to redress the balance in these things, after such a cloudy month in this part of the world last month.

Figure 3

To put it into perspective, the sunshine totals so far this month in Western Scotland are higher than anywhere I can see in the western Mediterranean, with Alicante the only station to have recorded more than 100 hours this month (fig 4). Having said that the potential daily sunshine is higher the further north you go at this time of year, which does help a bit.

Figure 4

***Updated 10th May 2017 ***

Due to the unprecedented numbers that have been looking at this article, I thought that any new readers would like to see if Tiree did actually get 15 hours of sunshine yesterday, not quite they got 13.7 hours, nevertheless there are still currently the sunniest place this month in Western Europe with 126.9 hours of sunshine in just nine days (fig 5), that’s an average of 14.1 hours per day. Sadly today, there are cloudy skies over Tiree, but it was good while it lasted.

Figure 5

Liscombe top of the shop

Figure 1

It’s not very often that you’ll see Liscombe in Somerset (and not in Devon as I had always thought) as the warmest place in the British Isles, but it happened today with a temperature of 15.0°C at 15 UTC (fig 1), in fact it was a southwest one two with Exeter Airport second in the table (fig 2), but I bet you won’t hear about that on the BBC weather.

Figure 2

You can’t even call Liscombe a village in all honesty, there is a Liscombe Farm, but the AWS is a little way to the east up what looks a very lonely lane on Exmoor at a height of 348 M (fig 3), so it might be getting a little help from the northwesterly wind.

Figure 3 – Liscombe courtesy of Google Maps

The 1⋅6% humidity at Altnaharra…

2016-12-03_154343

Figure 1 – Courtesy of the BBC

I came across this news story whilst reading a book called “Since records began” by Paul Simons. On researching the event on Google I found this news article about it on the BBC website (fig 1). There’s no doubt that the 18th of February 2003 was a mild day – the maximum reaching 11.5°C at Altnaharra making it was the warmest place in the UK. This was in no doubt due to a foehn effect in the strong southerly flow over the mountains to the south.

But it wasn’t the temperature that was the remarkable thing as Paul Simon’s mistakenly suggests in his book, but the relative humidity. In the 0952 UTC SYNOP observation from the automatic weather station [AWS] the dew point was an astonishing -39.9°C with a relative humidity of just 1.6%. The Met Office doubt that this was correct  and say that the relative humidity was closer to 8%. I’m not sure how they can be so certain about this, it maybe because they have access to one minute data from the AWS, but even so, a humidity as low as 8% must still rank as one of the lowest reported in the UK at a low-level station.

I love how Andy Yeatman sidesteps any embarrassment over this apparent mistake, I think in the news item almost trying to suggest that the wet bulb reservoir may have been frozen and the wet bulb had dried out, but if that was the case then the wet bulb temperature and hence the dewpoint, would have been much higher and not lower. Here’s the thermograph for that period (fig 2).

thermograph-for-altnaharra-1146-16-02-2003-1800-19-02-2003

Figure 2

And here are the hourly observations for Altnaharra for that day (fig 3). The winds do look a little strange and were flitting around a bit around 08 UTC.

2016-12-06_155947

Figure 3

The 12 UTC chart (fig 4) is dotted with low dew point observations across Scotland that day, notice the -11°C at Cairnwell and the -13°C at Kinloss.

synops-1200-utc-on-tue-18-feb-2003

Figure 4

The Torrey Canyon and the Seven Stones reef

The Sevenstones Lightship (fig 4) is anchored 15 miles (24 km) to the west-northwest of Land’s End, and 7 miles (11 km) east-northeast of the Isles of Scilly (fig 1). According to Wikipedia, there has been a Lightship there since 1841, to warn vessels of the danger of the Seven Stones reef, which over the years has sunk 71 named ships, and possibly another 200 unnamed others. I would like to give you more details about the Seven Stones reef but it’s impossible to get a decent detailed bathymetric map for around the coast of the UK, it seems that although we may have ruled the waves for a long time, we now charge an awful lot for finding just out how deep the waters are around our sceptred Isle, perhaps the Ordnance Survey can take over the Hydrographic Office and free up some of this data, but I digress.

The Seven Stones reef is where the Torrey Canyon came to grief 50 years ago on the 14th of March 1967. The accident happened in daylight, when the ship was still to the southwest of the Lightship, but the reef is almost 15 miles long. The board of inquiry laid the blame on the Captain, who was apparently taking a shortcut to save time getting to Milford Haven (fig 2), maybe if their approach had been at night, he might have spotted the light and avoided the disaster, who knows.

Figure 2

Believe it or not this article started out being about the wave heights this Winter reported by the Sevenstones Lightship! I didn’t at first consciously connect the 50th anniversary of the Torrey Canyon disaster with the Sevenstones Lightship, so here’s what’s left of the original article that I’ve written.

Figure 3

The above chart is of hourly wave heights, as reported by the Sevenstones Lightship from the 1st of December 2016 through this last Winter (fig 3). On top of the hourly scatter graph I’ve overlaid four of this seasons five named storms. The highest reported wave height of 7.4 metres this Winter, occurred during the unnamed or Candlemas low of the 2nd of February. The other named storms align poorly with any of the peaks in the 24 hour moving average of wave heights that I’ve also plotted for Sevenstones though.

Figure 4 – The Sevenstones Lightship

The last week on Mount Washington

Figure 1 – Courtesy of Mount Washington Observatory

The last week’s weather has been quite eventful atop Mount Washington, in the (very) White Mountains of New Hampshire. The observatory reports every six hours and here are the plotted SYNOPs for the last week (fig 2). As the low that produced the nor’easter of the last 24 hours passed to the east, the winds at the observatory increased to mean 82 knots at midnight.

Figure 2

As you can see last week the freezing level was above the top of the mountain (6,288 feet) and there were rain showers in a force 10 southwesterly, and just three days later the air temperature had fallen to -38.0°C and the winds had increased to mean 65 knots and veered west northwesterly. There are a couple of things that puzzle me about their observations, and one of them is snow depth. Why do they even bother trying to report a representative snow depth? Last night for instance, the mean wind speed was 82 knots (94 mph) and was gusting to 128 knots (147 mph)? And yet between midnight and 06 UTC, they reported that the snow depth had increased from 20 to 21 cms (fig 3). There is no way on earth that could be level snow, and what snow that did stick would be on the lee side of the mountain or observatory and considerably drifted and corniced. By the way, I’m assuming that the local nine group they use in their observations (93128), is in fact a gust group that only seems to be added, when the gusts are 100 knots or higher. I know that the Americans, like the Australians, aren’t big fans of the SYNOP format, but why can’t they just use the WMO standard reporting group for reporting gusts?

Figure 3

In comparison and with typical German precision at the Zugspitze Observatory in the Alps they do things a little more by the WMO book (fig 4). They report hourly observations for a start, that includes gusts, a believable snow depth, it may well be that because the winds are lighter there that they can do this more easily. Snow depths increased in excess of 4 metres during the last week there. They also report rainfall (equivalents) and air pressure adjusted to the 700 hPa level, which Mount Washington don’t do in a four group, just a ‘as read’ pressure in a three group. One thing that the Americans do report, which I think should be adopted more widely, is six hourly max and min temperatures.

Figure 4

Make that 17°C in Devon

Temperature now 17°C in Bradninch at 1350 UTC a gloriously sunny spring afternoon which makes a change from the overcast weather of the last few weeks.

Figure 1

The AC layer has thinned, and it’s been sunny for most of the last hour.

Figure 2

As an ex-metman I don’t get round to doing many SYNOP observations of my own these day, so when the Exeter airport observation went missing (again) and the temperature here reached 60°F, I thought that I would make up a WMO designator (03838) for our village of Bradninch, and add one of my own SYNOP observations with a little help from my trusty Vantage Pro.

Gust to 119 mph at Ushant

Figure 1

I haven’t been keeping count, but there seems to have been no end to the number of vigorous lows running across France since the New Year, and today is no exception. The gust reported in the 12 UTC plotted observation (fig 1) from Ouessant-Stiff (WMO 07100) of 103 knots or 119 mph, actually occurred at 08 UTC (fig 2), and I must admit that I never realised just how fiery the latest low had been went it made landfall this morning.

Figure 2

 Here is a list of the highest gusts as reported in the 12 UTC SYNOPS (fig 3). I don’t know why, but we seem to call the French island of Ouessant – Ushant.

Figure 3

Figure 4 – Le phare du Stiff (courtesy of Wikipedia)

Kurt slips between St Mary’s and the Seven Stones Lightship

Low Kurt is now moving quickly north, and just before 11 UTC had slipped between the Scilly Isles and the Seven stones Lightship (fig 1).

Figure 1

Here’s a bit of a close up (fig 2), the highlighted station is St Mary’s, the observation to the northeast is the Seven Stones Lightship.

Figure 2

It’s been quite a couple of days at St Mary’s here are the last 24 hours plotted observations (fig 3). There’s a sharp drop in temperature behind the occlusion from 9.6 to 5.1°C I notice.

Figure 3

And here’s the Lightship at Seven Stones, although it looks almost circular in this image, I’m sure that it does have a bit of length about it.

Figure 4

A little bit wilder than in the image as you can see from the observation from the Lightship itself (fig 5).

Figure 5

Looking back at the Burn’s day storm

Figure 1

Better late than never I thought that I would look back at the Burn’s day storm that occurred on the 25th and 26th of January 1990 with the help of the NCEP reanalysis data. As well as SYNOP data, I can now overlay a 2.5° x 2.5° grid of MSLP reanalysis data to fill in any missing gaps in the coverage. Of course it would be better if this grid were a little finer, but beggars can’t be choosers, and it does so improve the contouring. One thing I would say is that although we may not have had the weather buoys that we have these days there were a lot more ship reports back then, probably due to greater efforts made after the October storm of 1987.

Figure 2

It’s also a chance to see some of the old stations, that sadly have now disappeared. In these days of AWS you would have thought that there would have been a renaissance in observing sites at places such as Lighthouses, but automating the light didn’t mean that Trinity House were going to automate the weather observations from them, which is a great shame, and a missed opportunity.

The Burn’s day storm was a much deadlier storm than the one of October 1987 and led to the death of 97 people in this country, and 30 more has it tracked across the low countries. The Wikipedia article about it says that this was due to the fact that it occurred in day time, which may be true, but the winds across the southwest look a lot more severe at least to me. The highest gusts in the storm was 93 knots (107 mph) from Gwennap Head and Aberporth, but although the highest gust on the 12 UTC chart was 90 knots (fig 3), it was the mean speeds that were the main feature of the Burn’s Day storm as far as I can see, with many stations across the southwest reporting storm force winds, Beaufort force 10 with mean speeds of 48 knots or higher.

Having said that all that about Lighthouses, Gwennap Head is not one of them (img 1), even though it sounds like it should be, but just a mere Coastguard look-out station, a little like the one at Berry Head, and lying just a few miles southeast of Lands End.

Image 1 – Courtesy of Wildlife Insight

Image 2 – Courtesy of Bing Maps and the Ordnance Survey

Wolf Rock is a lighthouse though (img 3), and lies around 14 km to the southwest of Gwennap head, and I wonder just how windy it got there on that Burn’s day? I imagine that the gusts probably weren’t just quite as strong as on the headland, even though the lighthouse (which was finished in 1869) stands 41 M tall (135 ft), I imagine that the westerly violent gale (Beaufort force 11) blowing up those 66 M (216 ft) high cliffs may have added an extra bit to those gusts. I bet you could hear the sound of a wolf from the rocks on that day though.

Image 3 – Courtesy of Wikipedia

Intense Ottawan high

Figure 1

There’s an intense high sat over Ottawa on the 06 UTC chart this morning of around 1044 hPa. You usually associate light winds with anticyclonic weather, but not this morning on Mount Washington just to the southeast of the centre in New Hampshire, the wind from the observatory was meaning 62 knots (77 mph) at 06 UTC, with an air temperature of -24.4°C, and a resultant wind chill of -47°C (-52.6°F (JAG)).

Figure 2