El Niño hangs on into May


Latest SST (courtesy of NOAA-NCEP)

The latest El Niño (for region 3.4) which started back in March 2015 continues into what is highly likely to be its final month of May 2016 according to the latest Oceanic Niño Index [ONI] figures that have just been released. I say that because the ONI is a three-month running mean, and the latest value for region 3.4 during May was +0.30°C which is below the 0.5°C threshold and markedly down on the +1.09°C of the previous month. That’s a duration of 15 months, which could have easily have been four months longer if it weren’t for a stalled start in had. Despite this it still makes it the second longest El Niño in the current series back to 1950, and it also had the highest anomaly of +2.3 of any other event. That still might only make it the second warmest behind the 1997-98 event, but as with everything to do with these cycles it may be down to which region and what algorithm you use to decide these things. It’s interesting to see the cold waters spread across the equator from east to west and splitting the anomalously warm ocean.

El Niño & La Niña Cycles January 1950 - May 2016

El Niño & La Niña Cycles January 1950 – May 2016

Tabulated Oceanic Niño Index [ONI] January 1950 - May 2016

Tabulated Oceanic Niño Index [ONI] January 1950 – May 2016

Oceanic Niño Index [ONI] January 1950 - May 2016

Oceanic Niño Index [ONI] June 1986 – May 2016

Warmest May globally

It’s a wet Sunday afternoon here in Devon and well I’ve been mooching around looking for an article to write…

The latest Global temperature [GISS] data has been published by NASA, and it shows that the calendar month of May 2016 was the warmest on record with an anomaly of +0.93°C for the combined global land and sea surface temperatures. The record for the previous warmest May didn’t last long, as it was only set in 2014. I make the linear trend from 1880 +0.071°C per decade, but the linear trend of the last 50 years has increased to 0.156°C per decade, and yes I’m aware that 1967 was in a time of global cooling and that’s why the slope is so steeply upward.

May surface temperature anomalies GISS Global land & sea

May surface temperature anomalies GISS Global land & sea

The one crumb of good news for all you global warming deniers out there, is that May displayed the third successive decline in monthly anomalies since the record warmest month ever of +1.66°C was set back in February. Having said that the inset chart that I’ve placed inside the main chart is the absolute mean anomaly for each month since 1880, and as you can clearly see the larger magnitude anomalies occur in the winter and the mean falls on average to a minimum in July. So it’s not unreasonable to expect in each year a fall in anomalies until the Autumn arrives and they increase again. You could use a set of values like this to seasonally adjust the global temperatures but I would never consider doing it. And finally here’s the global picture of anomalies in May.

GISS Surface Temperature Analysis May 2016

GISS Surface Temperature Analysis May 2016 (courtesy of NASA GISS)

Recent sunshine totals

Daily sunshine 24 May - 6 June 2016

Daily sunshine 24 May – 6 June 2016

Excuse the rant

I saw one of the BBC forecasters today show some sunshine statistics for the UK and the stark difference between the totals from the east and the west. That got me to thinking that I’ve never really done very much with sunshine stats from SYNOP observations, so I set myself a little task to knock up an application to do just that this afternoon. <rant>The reason why I haven’t done it before is probably due to the lack of sunshine reporting stations in the UK which are released by the Met Office! It might have its headquarters in Devon, but there is just one sunshine reporting station in the whole of Cornwall and Devon, have a look at the coverage in France and Germany and see the difference. There are many climatological stations out there that the Met Office are just never going to release the data for – this side of hell freezing over – which I think is a very great shame, in fact it’s worse than that, it’s a scandal, after all it’s our – the public of this country’s – data. My plea to the Met Office is to please release as much climatological data as you can, you might not want to do much with it, but I certainly can. The sad thing is that I wouldn’t even be able to process this data and present you with these maps, charts and tables if it wasn’t for a Spanish web site, if I depended on the Met Office I would have no observational SYNOP data, they would rather just sit on it </rant>.

The sunshine data

Anyway getting down from my soapbox and back to the sunshine totals from the last two weeks, below is a tabulated ranked list of the 52 sites across the UK, and as you can see Tiree tops the list with over 170 hours in 14 days, or 12.2 hours per day and 72.6 of the theoretical maximum available – if my astronomical functions are working correctly. Bottom of the list is poor old Leconfield on Humberside with just 21.3 hours in the two weeks, or just over 20% of the possible maximum. Having said that there are a great many cloudy stations at the bottom of the list, and all in the east of the country, all in all a very interesting spell of weather. Most of the southern and central European countries support the reporting of daily sunshine data in their SYNOP/BufR observations. The trick is because of the various time zones across Europe there are some countries that report sunshine at midnight rather than 06 UTC, so I still have some work to do for the more eastern countries to get the maximum coverage.

Daily Bright Sunshine 24 May 2016 - 6 June 2016

Daily Bright Sunshine 24 May 2016 – 6 June 2016

May Pressure Patterns

When statistics can be misleading

I’ve always liked monthly mean pressure maps they can be very useful at summing up the weather of a month at a glance. But sometimes they can be very misleading and not at all helpful, take a look at the anomaly chart for May 2016 below as a perfect example:

Mean Sea Level Pressure & Anomalies 01 May to 31 May 2016

Mean Sea Level Pressure & Anomalies 01 May to 31 May 2016

As you can see the central north Atlantic had anomalously higher pressure than average (+2 hPa) in the month of May, with a lower than average pressures (-4 hPa) between Portugal and the Azores and across the bulk of southern Europe. Higher than average pressure to the SW of the Azores produced an intense high pressure cell in the southern Atlantic, but they were few isobars across the bulk of the central Atlantic, British Isles  and most of central Europe. Now look at the month in little more detail and broken down into three parts, early, mid and late:

Mean MSLP & Anomalies Monthly (3x3) May 2016

Mean MSLP & Anomalies Monthly (3×3) May 2016

And as you can see from the above charts, splitting the month into three separate periods show you why there is a distinct lack of isobars in the monthly mean. The first chart shows that for the first 10 days of the month fairly strong and warm south or southeasterlies predominated (and hence the record CET values), but from the 10th to the 20th the flow reversed, and the pressure anomalies instead of being above average over southern Sweden (+9 hPa) flipped to below average (-8 hPa) effectively cancelling out the southerly flow of the first ten days. During the last 11 days of the month negative anomalies (-3 hPa) continued across Germany and France, whilst higher than average pressure persisted to the northwest of the British Isles maintaining the NE’ly flow, and the cloudy cool weather in the east and heavy rain over the continent right through to the end of the month.

So what have I learnt – don’t rely on monthly charts – well not entirely at any rate. Perhaps ten days is the maximum period that a mean pressure charts can be relied on to identify trends, before those trends and features are distorted, smoothed or cancelled out by a distinct change of type part way through the month.

North Atlantic MSLP [UKMO] May 2016 (courtesy of the Met Office)

North Atlantic MSLP [UKMO] May 2016 (courtesy of the Met Office)

(todo: fix those dates in the titles 1-10, 11-20 & 21-31)

May Temperature Anomalies

Here is a chart of the reanalysis surface temperature anomalies for May 2016 using reanalysis data from NOAA. As you can see in May the bulk of the central Atlantic remained slightly cooler than average (-1°C), but the Arctic around Baffin bay and the Barents sea is anomalously warm (+5°C) as were northeast Russia and eastern Scandinavia. The recent heat wave over northern Pakistan and Afghanistan are clear to see (+5°C), as are the very warm conditions in central Canada (+4°C).

Air Temperature Anomalies 01 May to 31 May 2016

Air Temperature Anomalies 01 May to 31 May 2016

From what I can see, I would hazard a guess that when the global surface temperatures for May are released, although well above average, may not be quite at the record levels of previous months. Incidentally I’ve changed the mapping component that I use in my application, and there are some issues with it at the moment, one of the major ones being I can’t see much further south than the equator! I’ll have to get my programmer to pull his finger out and sort this out tout suite.

Rainfall: May 2016

Looking at the SYNOP rainfall totals for May 2016 over the British Isles it looks like the month has been below average for many parts. Wettest were Lusa in Skye (152.9 mm 24 hour total), and Capel Curig in Wales (127.8 mm 24 hour total). Parts of eastern Scotland and NE England were also very dry with Inverbervie driest with only 11.8 mm (24 hour total) and Aberdeen 14.9 mm (12 hour total). I don’t always get 100% of the possible SYNOP reports during the month although usually I do receive 98% or more from most stations. The other thing that can introduce differences is the fact that you can build an accumulation from 12 or 24 hour totals.

Driest Places - May 2016

Driest Places – May 2016


Accumulated Precipitation for May 2016

Accumulated Precipitation for May 2016

Accumulated Precipitation May 2016

Accumulated Precipitation May 2016

Of course there has also been the recent flooding of the last week in France and Germany from that small but intense low pressure system. Wettest place in northern France for the whole month appears to have been Trappes from the SYNOPs that I receive with 201.7 mm of rain (24 hr totals).

Accumulated Precipitation 2 May - June 2

Accumulated Precipitation 2 May – June 2

French Rainfall May 2016

French Rainfall May 2016

The wettest day seems to have been the 30th of May and overnight into the 31st. Here are the 24 hour totals up to 06 UTC on the 31st for most of France.

Daily Rainfall [mm] for Tue, 31 May 2016 at 0600 UTC

Daily Rainfall [mm] for Tue, 31 May 2016 at 0600 UTC

Synops for Tue, 31 May 2016 at 0600 UTC

Synops for Tue, 31 May 2016 at 0600 UTC

I can’t comment much on Germany because there’s a big hole of missing rainfall data in the middle of Europe this month by the looks of things.

Accumulated Precipitation - May 2016

Accumulated Precipitation – May 2016

Not clear what’s going on with the Germans, who seem to have joined the Danes in not reporting rainfall totals this month, either 6, 12 or 24 hourly which is a great shame. I’ll have to investigate, it could all be down to my parsing of course, but it maybe that the Germans have now switched to BUFR and OGIMET aren’t doing the conversion to SYNOP very well. There’s certainly a lot of blocks in a BUFR SYNOP as you can see in this example but no rainfall. I’ll email OGIMET about the problem but I’ve never received a reply for them before so the death by a thousand cuts continues as far as quality SYNOPs and climate data are concerned.

AAXX 01001 10400 02884 81801 10141 20134 30090 40139 50002 60001 8158/ 333 31/// 55/// 21552 31312 55300
20000 30000 60007 81657 87465 91001 90760 91104 90760 91203==

Central England Temperatures: May 2016

As far as I can make out, May 2016 was the 37th warmest in the Central England Temperature [CET] series that started in 1659. It had started coolly but warmed up significantly between the 4th and the 12th when two maximum CET records were broken (8th and 9th), but a colder week followed and wiped out a lot of the positive anomalies that had been gained.

Daily Central England Temperature - May 2016

Daily Central England Temperature – May 2016

Here are the May rankings since 1659, it certainly was the warmest since the exceptionally warm May of 2008, with a mean anomaly of +1.46°C. So although global temperature records are being broken on a monthly basis, CET records certainly aren’t.

Warmest May CET

Here is a look at all May’s since 1659.

May mean CET & anomaly

May mean CET & anomaly

And finally looking back over the last 62 years of CET monthly anomalies.

Central England Temperature Mean Anomalies 1954 - 2016

Central England Temperature Mean Anomalies 1954 – 2016