7th mildest March on record to date

With 28 days of the month now gone, March 2017 provisionally stands as the 7th warmest March in Central England back to 1772, with a mean temperature of 8.11°C which is +2.55°C above the 1961-1990 long-term average. Maximum anomalies are a little higher than minimum anomalies this month, indicating that the days have been a little milder than the nights. Mild has it’s been, there was little chance that it would catch the exceptionally mild March of 1957 though.

Figure 1

Cyclone Debbie

Figure 1- Courtesy of BOM

Here are some plotted observations from the aerodrome on Hamilton Island in Queensland Australia (WMO #94368), which seems to have been very close to the path of Cyclone Debbie. As is usual with SYNOPs from Australia they don’t include a gust group. I’m slightly suspicious of the wind speeds in the days before Debbie appeared on the scene at this station, because even without a cyclone, they seem to have been experiencing gale force winds since Saturday. Perhaps it’s just a very windy place, but if these winds are indeed correct then Debbie is one hell of a slow-moving cyclone, with hurricane strength winds for at least 12 hours or more on the island.

Figure 2

According to news reports from Australia, Hamilton Island was one of the few islands that wasn’t ordered to evacuate before Debbie’s arrival.

Figure 3

The relationship between volcanoes and Central England Temperature in recent years

 

Mount Pinatubo June 1991 Courtesy of Wikipedia

Now that I’ve discovered the VEI database from the NCEI, I can now overlay volcanic eruption events on top of the monthly CET anomalies and chart the results. In the above chart (fig 2) I’ve overlaid all the VEI 4 events or greater from 1980, and was surprised to find that there seemed little in the way of correlation between them. The Pinatubo eruption of the 15th of June 1991 for example was the first VEI 6 event since Tambora in 1815 (fig 1), and lifted more than 5 cubic kilometres of material 25 miles straight up into the stratosphere, coincidentally a typhoon that was passing close by to the Philippines at the same time scattered the ash from the volcano to the four winds. I thought the effects of this would have had a dramatic cooling effect on CET in 1992, but not that you would notice. Of course any cooling in a local temperature series may well be masked by other regional and global factors that influence CET that are going on at the same time, global climate is complicated.

Figure 2

29-30 March 1952 – Heavy snow and blizzards in the south

Figure 1 – Courtesy of the Met Office and © Crown Copyright

On the 29th and 30th of March 1952  a cold, strong easterly airflow affected the southern half of England with a period of heavy snow. According to the Weather log of the RMS snow varied from 3 to 6 inches and reached 10 inches at Northolt. The squally winds, which gusted to 60 mph, blocked 330 main roads across the south, with deep drifts. In places the temperature on the 29th remained below freezing all day, and the snowstorm was probably the worst to affect southern England in late March since 1916.

The Monthly Weather Report from the Met Office says about the weather at the end of March 1952:

Snow fell widely from the 27th onwards, notably in southern and Midland districts of England. On the 29th there was severe drifting. Snow was reported several inches deep in places in Scotland, while over a large part of southern England, depths of from 3 to 8 inches, with drifts in places of up to 6 feet, were reported on the morning of the 30th.

Figure 2 – Courtesy of Wetterzentrale

It may have been cold over the British Isles but the real cold air remained further east, but the easterly flow was enough to cause the country some real problems even though it was early Spring.

Figure 3 – Courtesy of Wetterzentrale

Here’s an earlier plotted chart that I found for Saturday night at 00 UTC. It’s from a great little book published by the Meteorological Office in 1956 called ‘Weather Map’, and which you can now download as a PDF from their library. It’s a shame that I didn’t realise this when I bought a second-hand version of it from Abe books earlier this year!

Figure 4 –  Courtesy of the Met Office and © Crown Copyright

Stratus reluctant to clear from central England

Figure 1 – Courtesy of the Met Office

The low stratus across central England has been very reluctant to clear today, and I notice this afternoon that it’s now spilling down the north coast of Devon in the easterly flow (fig 1). I also notice that there’s still some sea ice visible in the northern Baltic (fig 2).

22.2°C diurnal range at Altnaharra

Figure 1

A little slow on to this story, but the diurnal range from yesterdays maximum of 19.0°C at Altnaharra in Sutherland, and this morning’s minimum there of -3.2°C, was a whopping 22.2°Cor a full 40° Fahrenheit. Aboyne, Aviemore and Loch Glascarnoch followed closely behind with ranges of 20°C or higher. Coincidentally, I only wrote about the record low humidity at Altnaharra yesterday too. Altnaharra is the place for temperature variations it seemed because it did 18°C last December.

Capsizing of the Alexander Kielland – 27 March 1980

Figure 1 – Alexander Kielland Platform (Courtesy of Wikipedia)

On Thursday the 27th of March 1980 the Alexander Kielland platform capsized in a southeasterly gale in the North Sea 320 kilometers east of Dundee in the Ekofisk oil field. The low was by no means exceptional as far as the North Sea is concerned (fig 3), but the stress it placed on the badly welded joints of the flotel was more than it could take, and at around 1830 (maybe UTC, maybe not) the people on board heard a sharp crack as a fatigue crack occurred on the D-6 brace, and five of its six massive sea anchors broke as the platform listed by 30° (fig 2). A while later the other anchor gave way and the whole platform turned turtle.

One hundred and twenty-three people died (mainly Norwegians) that night in the worst disaster in Norwegian waters since World War II. Wikipedia has a short account of the disaster of 37 years ago, and this link is to the news item report by the BBC. As far as I can make out ‘320 km east of Dundee’ makes the Alexander Kiellands location around 56.3° north and 2.3° east (somewhere near the yellow dot on the chart). This rather spookily places it very close to a number of observations dotted around the Ekofisk field. To give you an idea of the weather within an hour of the disaster happening, the observation with the callsign ‘plat’ is reporting a mean wind speed of 36 knots from 120° with gusts to 44 knots in their 1800 observation. I’ve added a background field of reanalysis pressures and my own ‘bogus’ observation to try to correct the contouring, which is fairly accurate if I do say so myself.

Figure 3

Personally, I can only vaguely remember the capsizing, probably because I was involved in the Steel strike and there were so many disasters of one kind or another at that time.

Bracing at Skegness

Figure 1

The warmest places this afternoon seemed to be benefiting from foehn winds blowing down from either the mountains of Scotland or Norway (fig 1), where temperatures made it in the low 70’s Fahrenheit in southern Norway. In contrast to that, I wouldn’t fancy my chances sat in a deck chair on the front at Skegness this afternoon though.

 

25 March 2017 – sunshine total too low for Exeter?

I was a bit puzzled to see that there had been just 9.8 hours of ‘bright’ sunshine at Exeter airport yesterday (25th March 2017). As far as I can see the sensor there is either faulty, or is perhaps shaded by building or something. It was a sunny day in our part of Devon from dawn to dusk, as it was in most parts of the British Isles yesterday, and the only cloud there was was some thin high cirrus late in the afternoon, but in my experience with the Campbell-Stokes sunshine recorder of old is the sunshine trace for yesterday would have been uninterrupted from dawn, to maybe half an hour from sunset. I know that the electronic sensors the Met Office use are calibrated to map as closely as possible to the old sunshine recorders, but the bright sunshine threshold for yesterday must be set far too high for Exeter and Liscombe. Here are yesterday’s automated hourly SYNOPs from the airport (fig 1).

Figure 1

Admittedly Liscombe in North Devon also reported a low total of 10.0 hours, but Yeovilton to the east in Dorst reported 1.3 hours more, and Camborne in Cornwall reported 2 hours more (fig 4). I can understand that Camborne maybe has a clear ‘sea’ horizon to the west, and would maybe report up to 0.5 hours more than Exeter, because Exeter has hills to both its west (Dartmoor) and to its east (Blackdown), which will would make sunrise a little later, and sunset a little earlier. Here are the raw SYNOPs for Exeter which include an hourly total (fig 2) which give us a better understanding of the missing sunshine.

Figure 2

As you can see from the observations, the only hours that weren’t completely sunny were 06-07 (0.2), 16-17 (0.5), 17-18 (0.1) and 18-19 (0.0). Sunrise was at 0605 UTC, and sunset 1835 UTC (fig 3), so there were was 12.5 hours of daylight, and theoretically ~12 hours of bright sunshine in this part of Devon.

The night of the 24-25th was dry and the strength of the wind prevented any dew or frost from affecting the record from 06-07 UTC. The sunrise was at 0605 UTC, but only 0.2 hours of bright sunshine was recorded that first hour, I would have thought that at least 0.5 hours could have been recorded, maybe the Blackdown hills restrict the maximum total by more than I imagine.

Figure 4

Finally, here is a tabulated ranked list of yesterday’s sunshine totals from around the country, with a percentage of the possible maximum sunshine for each location (fig 5). The algorithm that I employ for the maximum amount of daylight is simply, the time difference between sunrise and sunset for each location, which I know is not a realistic value that any sensor could ever achieve, so the percentages will be slightly higher (~3%) than those in the table.

Figure 5

The acid test of course would be to examine a visible satellite image for yesterday evening, and by a stroke of luck, I just happen to have one that I archived. Why I didn’t think to look at this in the first place I don’t know, but it does show a thick wave-like cloud that sprang up late yesterday afternoon over west Devon, which no doubt is what limited sunshine at Exeter airport in the 90 minutes prior to sunset. I’ve learnt a salutary lesson from this particular blog, and that is don’t jump to conclusions and spout off about sunshine totals from remote observing sites, even if they are just 11 kilometers away!

Figure 6 – 1730 UTC 25 March 2017 (Courtesy of the Met Office)

I discovered quite by chance that a friend of mine had taken pictures of the sunset on Saturday evening from close by in Silverton, which do show the wave-like aspect of the cloud that sprang up over Dartmoor late that afternoon (fig 7).

Figure 7 – Courtesy of Warren Radmore

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