Remember the sunshine card?

If you remember ever having to change a sunshine card in a Campbell-Stokes recorder as an observer, then I’m sure that you’ll like this new way of visualising hourly sunshine data from stations across the UK that I’ve dreamed up (fig 1).

Figure 1

I don’t have the luxury of being able to receive minute data from the Met Office network, so the next best bet is to access hourly SYNOP data from OGIMET and put it together in some code and plot a gantt chart, which is exactly what I’ve done here (fig 1). It’s unique as far as my knowledge of visualising systems that don’t have network access to a remote AWS. There is a bit of guesswork about how you assign the hourly amount of sunshine to each hour during the day, I’ve made it so that the program defaults to the end of the hour before noon, and to the start of the hour after noon. The gantt chart format allows you to also see the approximate times of sunrise and sunset for each station. I’m pretty chuffed with the end result which only occurred to me whilst sun bathing in the garden this afternoon!

The other thing that it enables you to do is to watch sunshine total as they increase across the UK in real-time through the day (fig 2).

Figure 2

Something not quite right about this cold front

There’s a cold front – or should I say that there should be a cold front straddled across southwest England this morning. But you would be hard pressed to find it on the plotted 10 UTC chart (fig 1).

Figure 1

You might think that the cold front is associated with this batch of rain that’s now cleared through the southwest and is now moving northeast across the Midlands, but that rain can’t be the cold front because it’s just too far on (fig 2).

Figure 2

The cold front according to the T+06 forecast chart (and why do the Met Office not release their latest 6 hour analysis quicker than they do) is only across Cornwall at 12 UTC (fig 3).

Figure 3

So why is it, that if the cold front went through the Scillies at around 06 UTC (fig 4) (with moderate rain and a slight pressure kick), does the dew point there continue to climb, as if a warm front rather than a cold front has passed through?

Figure 4

Answers on a postcard please, or why don’t you just leave a comment. It would be so educational if the Met Office released the Synoptic Review (part II) that the Chief forecaster produces every six hours on the internet for all to read. I always found it fascinating reading as an outstation assistant, and am sure that a lot of people interested in the day-to-day weather across the country would find it fascinating too, I bet the answer is in there.

Overestimating cloud amounts

Since the Met Office have two AWS within 10 miles of home, I always keep a check on them, especially as regards cloud base and cloud amounts, because both Exeter airport and Dunkeswell come equipped with laser cloud base recorders [LCBR]. I have noticed though that as far as I can see they always seem to overestimate cloud amounts, especially of the low variety. Take this morning for instance, there’s no doubt that there was a good deal of low cloud about first thing, but quickly during the early morning here (and we lie around 8 km to the north of the airport), the cloud broke up to between 2 and 4 oktas, and now at 12 UTC, there no more than an okta. I realise that the LCBR can only sample one spot above the station, but from this morning’s reports from both stations you would have concluded that it had been mainly cloudy for much of the time, which as far I can tell it wasn’t (fig 2).

Figure 1

And here’s the visible satellite image for 11 UTC (fig 2):

Figure 2

It could be that there was stubborn bit of SC that just refused to budge, or maybe it was the algorithm that they use is skewed to guess (because that’s was it’s in effect doing) higher amounts than the LCBR is sensing. I did notice that the AWS reported hourly sunshine for the last three hours (0.5, 0.1 & 0.4) so it maybe that the cloud increased just as the AWS did an observation perhaps. Of course it makes not a jot of difference in the big scheme of things, if they were fed back into the models then it might, but I think very little from a surface observation (apart from pressure) are used in producing NWP forecasts.

Until this morning I was just plotting AWS without filling in the station circle with the total amount of cloud, but I figure if many of these AWS in the UK can report multiple layers of cloud, then why not report N the total amount of cloud, so with a little bit of code I now guess at N and plot it (fig 3).

Figure 3

Drought, what drought

Figure 1

Admittedly rainfall accumulations this month are completely topsy turvy, and it’s still been a very dry month in many parts of Scotland, but the meteorological drought that affected many parts of the south did come to an abrupt end this week with some heavy rain, as droughts so often do. I’ve tried to wheedle out plotting totals for stations where I had more than 25% of reports missing, having said that there are still a few oddities, Rhyll being one of them, although the 6.4 mm total there is kind of supported by the 13.6 mm at nearby Hawarden.

I’ve just rejigged the code for this application, and it now uses a combination of priorities to get the most accurate result. If there’s a 24 hour 06-06 total that’s great it will use that, and many of the main UK of stations have a 100% reception rate using that value alone. If there isn’t a 24 hour total, like in Ireland and parts of Europe, I add up the available 12 hour totals (06-18 & 18-06). Finally if there are only 6 hourly totals, as in the United States I add these up. The Americans, as far as I can see, don’t report nil rainfall totals as we used to do at one time, so you have to rely on the indicator in the initial block being correct. The whole area of rainfall reporting in SYNOP from different countries is a complete nightmare to program, and I still have to write code that throws back totals to the previous day, but for now this will have to do. If you have any complaints about any of the totals, please feel free to have a go yourself.

Bradninch top of the shop

The temperature at 11 UTC was 16.3°C here in Bradninch Devon from my trusty Vantage Pro. I notice that it had reached 16.9°C just before 12 UTC. The sea breeze that’s keeping it cooler at Exeter airport, hasn’t quite made it this far north as of yet.

Saturday, 25 March 2017 – 16 UTC observations

Saturday, 25 March 2017 – 12 UTC observations

21st March 2017

These are some plotted climate charts for yesterday across the British Isles and near continent. They include sunshine for yesterday, precipitation [06-06 UTC] and maximum [06-18] and minimum temperatures [18-06]. It’s not particularly exciting I know, but I was just looking at another way of displaying the charts that I generate from how I have done it in the past.

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.