The author: Dr. Donald Perkins at the weather station but, sometimes, on expedition.

Llansadwrn (Anglesey)

Diary 2017

Logo: Llansadwrn Weather - Melin Llynnon, Ynys Môn

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Times are GMT (UTC, Z). Observations at this station [ ] are 24-h 09-09 GMT, some others { } occasionally refer to other 24-h periods, extremes (first indications) are given in bold and are usually 21-21 GMT. When averages are referred to (.) compares with the last decade and [.] with the new 30-y climatological average [1981 - 2010]. All data are subject to verification and amendment.

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Dates of arrival of the chiffchaff in the garden in Llansadwrn 1998-2017. Another fine and sunny morning on the 25th and I heard straight away standing at the screen at 0900 GMT that the first chiffchaff had arrived. It was spot on the median date of arrival here, records back to 1998 (graphic left). Singing rather weakly it will take a few days to become stronger; it will be about 3 weeks before the females arrive. It was 9.6C and high-pressure steady on 1034 mb, highest of the month, with little or no wind. It was breezy, however, at the extremities of the high around N Scotland and the English Channel coastal areas. Another largely sunny day with a high solar radiation of 14.97 MJ m -2, highest of the month and the year so far (Aboyne 19.1C Charterhall 12.2h) [Max 15.2C Min 3.4C Grass -2.5C Pptn nil]. Another fine sunny day on the 26th with a sky of wavy cirrus clouds and several contrails to the NE and SW of here. Pressure was steady on 1026 mb, with UK high 1030 mb Tay Estuary, and there was a light NE'ly breeze and clear very good visibility Solar radiation a little less today at 14.48 MJ m -2. (Aviemore 19.9C Kirkwall 12.0h Valley 8.6h) [Max 13.5C Min 5.8C Pptn nil]. The 27th was fine and sunny with a light E'ly breeze backing from SSW'ly. The 3 oktas sky composed of cirrus and altocumulus. Sunny morning and after noon the wind veered S'ly and we caught a Föhn breeze the temperature rising to 17.4C for a while before the wind direction became unfavourable. Solar radiation today was 14.70 MJ m -2. (Aviemore 19.1 Capel Curig 16.9C Rostherne 11.8h Valley 10.8h) [Max 17.4C Min 4.4C Grass 0.7C Pptn nil]. Fine and bright to begin the 28th with a little weak sunshine. Visibility was moderate to poor with thick haze enhanced by Saharan dust. Pressure had fallen and was steady on 1016 mb with a disturbance over the Celtic Sea. Pressure was high 1029 mb Gibraltar Strait and the Adriatic and low 967 mb S Greenland. A fairly cloudy day apart from a glimpse of sunshine around noon; showery rain before midnight (Gravesend 19.1C Rhyl 15.5C St Athan 9.0 mm) [Max 14.8C Min 6.7C Pptn 6.2 mm]. A spell of rain after midnight mostly light heaviest around 05 GMT on the 29th with sky overcast at dawn with drizzle at 0900 GMT. A dull and misty morning with light rain and or drizzle through the day that was sunless (Cranwell 17.8C Rhyl 14.8C Whitechurch Pembs. 30.4 mm [Capel Curig wettest in Europe today 33.4 mm] [Max 12.6C Min 8.6C Pptn 5.3 mm]. Another very wet, but mild, day on the 30th. There was a little standing water at 0900 GMT and a temperature of 12.2C. Pressure was on 1012 mb and there was a cold front over the Irish Sea and low 983 mb W of Ireland. Pressure was high 1031 mb over the Adriatic and 1029 mb N Africa. Continued wet and windy with low ragged cloud on a moderate S'ly wind. Heavy pulses of rain from 1800 GMT (49 mm/h) petering out by 2200 GMT. The rainfall for the day 19.2 mm gave the wettest day of the month (Gravesend 22.1C Capel Curig 46.0 mm Herstmonceux 9.8h) [Max 12.2C Min 11.3C Pptn 19.2 mm]. There were a few patches of blue sky appearing at 0900 GMT on the 31st as pressure 1006 mb was rising. There was a blustery force 5 SSW'ly wind and a clearer slot developed with a little sunshine at times (Hull E Park 18.9C Hawarden 16.4C Harris Quidnish 32.8 mm Mumbles Hd. 17.4 mm Sheffield 6.3h) [Max 12.7C Min 9.3C Pptn 6.8 mm].

The rather wet month ended with a total of 135.6 mm of rain (213%) & [159%] of averages, most in 10-years and the 8th largest in March since 1928. Largest since 2006. A warm month the mean 8.3C (+1.6) & [+1.3] of averages, but sunshine was at a premium at Valley least since 2006 and ranked 32 on the Anglesey record.


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April 2017

April 1 - began mostly cloudy after a moderate shower of rain (5.8 mm/h) at 0536 GMT although now bright with some sunshine breaking through, somewhat misty visibility. Pressure 1007 mb was rising with a ridge to the W of Ireland from Atlantic-high 1027 mb lying off Iberia. The cloud was due to complex bands associated with a minor low 1003 mb over Wales. When the sun appeared it was quite pleasant; several large bumblebees were about the garden and from time to time disappearing under ground often into holes in the grass sward that for me are very difficult to spot, but for bees it seems no problem. Later they will pop up again from the 'invisible' hole hidden in the grass, they seem to like to build their nests in old tunnels left by moles which are frequent in the garden. (Gravesend 17.6C Lake Vyrnwy 22.4 mm) {Max 14.3C Min 8.0C Rain 0.3 mm].

View of Snowdonia from Llansadwrn.

The ridge if high-pressure moved across in the night, bright stars were visible at midnight on the 2nd and as a result there was a touch ground frost -0.7C by morning. Very good visibility with now no seen on the tops and N-facing slopes of the Carneddau Mountains. Pressure 1023 mb was rising in the ridge over the UK from high 1027 mb near the Iberian coast moving over Cap Finisterre by 0900 GMT. Fine and sunny, but a cool 8.0C, the slight white frost on the fields had disappeared and after the clear sky convection was building to the south and west and Valley reported light showers. Here the sky cleared again to give a sunny afternoon with the butterflies putting in an appearance along with the large bumble and honey bees. [Max 14.3C Min 3.5C Grass -0.7C nil rain]. A bright, mostly sunny, but breezy morning on the 3rd with good visibility. Pressure was steady on 1022 mb with highs 1028 mb S North Sea and 1027 mb Iberia. Deep low 968 mb SE Greenland meant that isobars were tight to the NW of here. The afternoon turned cloudier and slight showers of rain developed during the evening [Max 11.5C Min 5.5C Rain 1.3 mm].Dates of flowering of bluebell in the wood in Llansadwrn 1996-2017. A fine and bright morning on the 4th with a light cool N'ly breeze, temperature 8.2C (dewpoint 5.5C). Pressure 1029 mb was rising rapidly with high 1034 mb sea area FitzRoy. Cloud had moved SE overnight and there was a frontal wave over SW UK associated with low 974 mb N of Iceland. Mostly sunny afternoon. There were several bluebell flowers out in the wood, about the same date as last year (graphic left), 3 days earlier than the median date of flowering here back to 1996. Both 10-days earlier that 2015 and equal to 2014; the earlier has been 17 March 2012. Leaves on horsechestnut are expanded and flowers have formed, but are not yet open. A few bud scales from sycamore have appeared on the ground and seeds have begun germination [Max 11.5C Min 7.3C Rain nil]. The morning of the 5th was disappointingly very dull, overcast and a cool 7.6C, there was moderate dew with the grass minimum reading 0.0C, so no frost. Pressure was on 1034 mb with a high 1037 mb off SW Ireland. The afternoon was brighter with a little sunshine breaking through [Max 11.7C Min 4.3C Grass 0.0C Rain nil].

Meteosat MSG image (c) EUMETSAT at 15 GMT on 06 April 2017, courtesy of Bernard Burton. Another cool dull day on the 6th with skies overcast giving 'anticyclonic gloom'. Pressure was steady on 1033 mb with high 1034 mb over SW UK and Ireland. There was no change in the blanket of cloud and the day remained sunless. Not so in S Wales, S England and France where it was mostly sunny. [Exeter 12.5h St Athan 11.5h Bordeaux 12.4h Valley nil] [Max 10.6C Min 4.7C Grass 0.2C Rain nil]. A bit brighter on the 7th with a patch of blue sky seen at 0900 GMT. Keeping dry, and seemingly cool although a little above the averages for the beginning of April here. After an overnight minimum of 6.7C a temperature of 8.9C to begin the morning and rising to 13.6C after noon when it had become sunny, a day mean of 10.2 (+0.9) & [1.2]. High 1029 mb was now over Cardigan Bay with the same pressure in Llansadwrn. Wisley 18.8C Cardiff 16.8C Camborne 12.6h St Athan 12.4h Valley 6.1h]. Overnight the cloud had moved away and on the 8th it was one of those rare clear sky mornings. It was to be a perfect day with wall to wall sunshine, a light NE'ly breeze at first soon veering S'ly in a Föhn-like breeze (up to 15 mph at 1434 GMT) the temperature rose to over 18C between 1320 and 1600 GMT with a maximum of 18.8C, highest of the month, with the relative humidity of 46% at 1420 GMT, lowest of the month. (Hampton WW 21.4C Trawsgoed 20.7C Charterhall 12.8h Lake Vyrnwy 12.7h) Gorddinog 17.1C Gorwel Heights 16.6C [Max 18.8C Min 3.0C Grass -1.7C Rain nil]. There was some cloud in the sky on the 9th, 5 oktas, with moderate visibility in thick haze recorded as smoke, a pollution haze developed as a result of sunlight on atmospheric pollutants resulting in elevated concentrations of ozone. The monitor high up on Marchlyn Mawr at 2100 ft where an instrument recording ozone (Welsh Air Quality Forum) measured nearly 120 µg per m-3 . The morning turned cloudier from the west and the afternoon had little in the way of sunshine (Cambridge 25.5C Aberdaron 11.5C Shoeburyness 12.6C Valley 2.5h) Gorwel Heights 16.9C, highest of the month [Max 14.4C Min 9.1C Rain nil].

A bright morning on the 10th with pressure 1028 mb rising. Pressure was high 1026 mb over Mediterranean regions and was 1035 mb W of Ireland. The fly in the ointment was low 991 mb mid-Norwegian seaboard resulting in tight isobars over Britain and a cool NNW'ly airflow and a cold front over S England. With the wind off the Irish Sea rising over the mountains the day kept mostly cloudy here with a few glimpses of sunshine (Herstmonceaux 15.9C Katesbridge -1.1C Cluanie Inn 12.8 mm Exeter 11.1h Aberdaron 9.4h [Max 11.3C Min 3.4C trace]. Beginning mostly cloudy on the 11th some weak sunshine developed and glimpses of sunshine cloud thickened in the afternoon (Heathrow 16.7C Baltasound -1.6C Resallach 73.0 mm St Athan 12.5h) [Max 12.0C Min 3.2C trace]. There was slight shower of rain at 0800 GMT on the 12th then light rain for a while with poor visibility. Backward trajectory analysis of air arriving over Anglesey at 1400 GMT on 14 April 2017. Researched on the NOAA ARL Website.Pressure was on 1019 mb with a low 995 mb N of Scotland and a cold front tracking S over the Irish Sea. There was a moderate shower of rain at 1400 GMT then it clear away with some sunny spells developing. (St James Park 17.6C Cluanie Inn 21.2 mm Tiree 9.2h) [Max 12.1C Min 7.5C Rain 2.1 mm]. A dull and almost calm morning on the 13th with an air from the W at 0900 GMT. Pressure was steady on 1019 mb with low-pressure 1003 mb to the N and high-pressure 1025 mb to the SW of Britain. Mostly cloudy (Heathrow 15.4C Kinlochewe 8.0 mm Lerwick 7.7h) [Max 10.0C Min 5.3C Rain 1.7 mm]. Similar on the 14th after recent rain keeping overcast all day with low cloud/ fog on the mountains. There was a cold front over the Irish Sea at noon with low 998 mb SE Iceland. There was rain from 1300 to 1700 GMT, moderate at 1415 GMT. There was Saharan dust high in the air overhead between 1100 and 1700 GMT and some of this was washed out continuously by the rain over this period. The dust, a light reddish-brown in colour (colour when collected and dried MUNSELL® COLOR 5YR 6.5/4). Backward trajectory analyses using the HYSPLIT dispersion model, courtesy of the NOAA ARL Website indicated that parcels of air arriving over Anglesey between 4250 and 5000 m AGL had a Saharan origin (graphic left). Rainfall for the day 6.6 mm was the largest of what was a dry month. Sunless (Pershore College 16.1C Baltasound -0.3C Capel Curig 15.6 mm Lerwick 7.0h) [Max 11.3C Min 7.5C Rain 6.6 mm].

Backward trajectory analysis of air arriving over Anglesey at 0700 GMT on 16 April 2017. Researched on the NOAA ARL Website. The sky had cleared overnight and the air minimum on the 15th had been down to 3.0C and there was a touch of ground frost -0.5C. At 0900 GMT cloud was developing but it was bright with sunny spells. A fine day with some sunshine then turning cloudier later (Heathrow 15.7C Aboyne -1.5C Resallach 14.8 mm Charterhall 11.8h) [Max 12.5C Min 3.0C Grass -0.5C 0.2 mm]. The 16th began overcast with slight rain falling depositing some more light reddish-brown Saharan dust. Backward trajectory analyses using the HYSPLIT dispersion model, courtesy of the NOAA ARL Website indicated that parcels of air arriving over Anglesey between 2000 and 3000 m AGL came from a pool of dust trapped within high-pressure south-west of Ireland that probably had a Saharan origin (graphic left) of similar origin to the confirmed events on the 14th and 11th March. At 0900 GMT the temperature was 7.5C and pressure was 1022 mb with high 1028 mb Biscay, but there was a frontal wave over the Irish Sea. For about an hour in the afternoon the sky cleared and we had some sunshine that raised the temperature briefly to 12.9C before cloud encroached again ( Hurn 16.1C Altnaharra -0.3C Leconfield 11.0 mm Sennybridge 8.4 mm Camborne 10.4h) [Max 12.9C Min 4.3C Rain 2.1 mm]. On the 17th pressure 1024 mb was rising with high 1027 mb off SW Ireland; we were affected by frontal cloud associated with a low 1015 mb over Belgium. It was a dull morning, but looking a little brighter. The day was mostly cloudy with a little sunshine at times, the wind a light WNW'ly overnight backed NE'ly (Cardiff 15.6C Kinbrace -4.8C Fair Isle 7.4 mm Tiree 12.4h) [Max 10.1 Min 7.0C Rain nil]. Increasing cloud on the morning of the 18th, otherwise fairly bright with glimpses of sunshine. A cool night with a touch of ground frost (-0.9C) with moderate dew formation. Thickening cloud around noon, then brighter again during the afternoon with further glimpses of sunshine. Squirrels seen at feeding stations during the day [Max 10.6C Min 3.5C Grass -0.9C Rain nil]. On the 19th Welsh poppy flowers were seen out in the garden. Fine and dull, but becoming brighter although there were some spots of drizzle mid-morning. Fine and dry in the afternoon [Max 12.2C Min 4.9C Rain 1.7 mm]. It was dull, damp and cool on the morning of the 20th, brighter at times in the afternoon when warmer [Max 14.2C Min 8.3C Rain nil]. Continuing with overcast skies on the 21st in the cloud filled dust laden high pressure area 1035 mb anchored SW UK, N France and Belgium. Today it was reported that for the first time since the dawn of the Industrial Revolution no coal was used in the generation of electricity for the National Grid in Britain [Max 14.6C Min 8.9C Rain nil]. With pressure steady on 1032 mb and the high 1034 mb lying to the W of Ireland on the 22nd it was a much brighter day. At 0900 GMT the temperature was 9.9C and under a clearing sky, a short contra overhead, a band of cloud to the SW and some lenticular altocumulus clouds developing during the morning, and a light N'ly breeze it was a mostly sunny day. Solar radiation was highest of the month and year so far with 20.52 MJ m -2 with 790 W m -2 recorded in the hour from noon. Temperature wise it was not a very warm day with a maximum of 13.5C here and only 11.5C at Gorwel Heights (Usk 17.6C Shap -1.8C Glennanne 7.2 mm Morecambe 13.3h) [Max 13.5C Min 5.5C Grass 0.7C Rain nil; Valley 6.7h]. The 23rd was also fine and bright with very good visibility and a light N'ly breeze; cloudier 5 oktas increasing. Pressure 1028 mb had fallen a little as high 1029 mb Shannon declined. There was a low 1013 mb between Iceland and Scotland with another 996 mb S of Greenland and W of the Azores [Max 14.5C Min 5.6C Rain 0.2 mm].

Fresh snowfall on the Carneddau Mountains..On the 24th pressure 1017 mb was falling after a recent shower of rain at 0900 GMT. In a complex synoptic pattern there was a low 994 mb S Norway with an associated cold front over the Isle of Man with further frontal waves to the N over Scotland. Temperatures began to fall in the afternoon, with winds from the N, bringing showers from Arctic regions falling as ice precipitation on the summits of the Snowdonia Mountains during the day (Bournemouth 16.5C Benson -0.3C Cluanie Inn 19.2 mm Prestwick 10.3h) [Max 10.8C Min 7.8C Pptn 2.1 mm] At Ny Alesund in the Arctic the maximum temperature today was -6.7C and the minimum -12.3 with 12 cm of snow; Svarlbard was Max -4.6C Min -11.7C with 30 cm of snow; and at Tromso Max 1.9 Min -6.0C and 20 cm snow. In the early hours of the 25th ice precipitation consisting of snow pellets and snow left slight snow lying at 0900 GMT at 1800 feet on the N-facing slopes of the Carneddau, earlier sprinklings were at 1000 ft near Llyn Ogwen and also on Cadair Idris. There were light accumulations over 2250 ft on the Carneddau and Snowdon. Here the overnight minimum was 2.3C, lowest of the month, with a touch of ground frost -0.6C after showers of snow pellets at 0230 GMT. The day was bright then sunny [Valley 9.8 h], a cold breeze strong enough to take off newly opened leaves on the trees, and very clear visibility in the clean arctic air. At 1715 GMT we had a shower of very large snow pellets measuring 10 mm (Cardiff 12.4C Redesdale -4.1C Aboyne 18.6 mm Manston 12.6h) [Max 10.7C Min 2.3 Grass -0.6C Pptn 0.2 mm]. Some more snow pellets fell after midnight on the 26th and there was some fresh snow seen on Snowdonia mountaintops at 0900 GMT. Snow was lying as low as 2250 ft on the lower slopes under the Black Ladders. Another very fine sunny day with a chilly wind that moderated later in the afternoon. Solar radiation of 23.66 MJ m -2. was the highest of the month (Killowen 13.6C Sennybridge -4.8C Scarborough 10.6 mm Bude 13.3h) [Max 9.5C Min 3.2C Pptn 0.1 mm].

A dull cloudy morning on the 27th with recent slight rain continuing after 0900 GMT turning showery. High-pressure 1028 mb was still off SW Ireland and there was a low 1005 mb S Norway with a warm front over the Isle of Man and the Irish Sea [Max 10.9C Min 3.1C Grass -0.2C Rain 1.4 mm]. Not a lot of change on the 28th with overcast skies, low cloud, rain and mist. Today's maximum 9.2C, jointly with the 26th, lowest of the month [Max 9.5C Min 7.4C Rain 1.3 mm]. Brighter and breezier on the 29th with very good clear visibility under the cloud. Pressure was on 1013 mb with tight isobars and fronts to the W of Ireland while pressure was slack over England to the E (Gravesend 16.8C Drumnadrochit -1.5C Capel Curig 3.2 mm Herstmonceaux 10.5h) [Max 12.8C Min 5.7C Rain nil]. Fine, but dull and continuing cool on the 30th with pressure 999 mb falling with a low 986 mb off SW Ireland. Rain on a frontal system was sliding northwards over SW England, S Wales and Ireland did not reach here until later (Gravesend 18.4C Mount Batten 23.6 mm Milford Haven 9.8 mm Leconfield 9.5h Bala 7.5h Valley 0.0h) [Max 14.0C Min 7.7C Rain 0.7 mm].

The month ended with a total of just 22.0 mm of rainfall (41%) & [35%] of averages, least since 2010 and the 6th driest April in Llansadwrn since 1928. The mean temperature was 9.0C (-0.3) & [+0.1) of averages, highest since 2014 ranking 16th here since 1979. A disappointingly cloudy month, sunshine at Valley was lowest since 2005 and one of the 10th dullest on the Anglesey record since 1931.


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May 2017

May 1 - began brightly with hazy sunshine after slight rain showers in the night there was moderate visibility and a light NE'ly breeze. Increasingly sunny in the afternoon when the sky cleared giving a fine sunny evening (West Freugh 20.6C Dunkerswell Aerodrome 33.2 mm St Athan 17.2 mm Kinloss 13.1h) [ Max 16.1C Min 5.5C Rain nil]. Mostly clear sky overnight and the morning of the 2nd was very fine and sunny. An overnight minimum of 5.5C and 1.6C on the grass, good visibility with light smoke haze. Pressure 1021 mb was rising with high 1034 mb over the S Norwegian Sea. A sunny afternoon (Achnagart 21.0C Tain Range -1.6C Frittenden 5.0 mm Lerwick 14.8h Aberdaron 13.9h) [Max 16.4C Min 6.5C Rain nil]. Another fine and sunny day on the 3rd with pressure steady on 1028 mb under the influence of a ridge from Norwegian Sea high 1041 mb, good visibility with moderate smoke haze. There was a cool light to moderate NE'ly breeze, although cloud increased the afternoon was mostly sunny (Achnagart 20.2C Porthmadog 19.2C Aviemore -2.4C Manston 4.4 mm Aberdaron 14.0h) [Max 15.0C Min 6.5C Rain nil]. Mostly clear sky on the 4th with some cumulus and altocumulus lenticularis developing later to disperse. There was moderate smoke haze and moderate levels of pollutant ozone in the air; the monitor at Marchlyn Mawr indicated 101 µg per m-3 . Pressure was steady on 1026 mb with high 1024 mb over the Norwegian Sea, low 998 mb mid-Atlantic to the SW, and a complex low pressure 1015 mb over the eastern Med and 1011 mb over the western Med. Sunny again with a light to moderate ENE'ly breeze by afternoon with visibility becoming clearer and very good [Max 17.3C Min 8.1C Rain nil]. After a mostly clear night the 5th began with sunshine and a cold force 4 NE'ly wind. There was a little cumulus and cirrus clouds, otherwise a nice blue sky though somewhat hazy due to pollutant smoke (04). The solarimeter was unobscured all day with a good smooth curve: total global solar radiation was 25.54 MJ m -2 highest of the month so far, with a high of 831 W m -2 recorded in the hour 12 to 13 GMT (Kinlochewe 19.9C Porthmadog 18.8C) [Max 15.9C Min 5.8C Rain nil].

On the 6th cloud had encroached and it was a dull day with cloud bases about 2500 ft on the slopes of the Carneddau Mountains. Again with a NE'ly breeze and moderate hazy visibility. The cloud had thinned by about 1800 GMT and there was a little weak sunshine, another dry day (Tyndrum 20.4C Milford Haven 17.4C Braemar -5.0C Scilly Is. 23.6 mm) [Max 12.9C M in 7.0V Rain nil]. The sky had cleared in the night and on the 7th it was a very fine sunny morning. Zero cloud as far as I could see from the weather station, very good visibility with a light NE'ly breeze developing after a calm dawn. Pressure 1023 mb was rising with low 1012 mb S Norway and low 986 mb over the Atlantic off Iberia and S of Greenland. A few very small cumuli appeared in the SW during the morning. Tiree with 15.0h had the most sunshine with Valley coming in at 14.5h and Dublin 14.8h. The highest maximum was 21.3C at Pershore [Max 15.4C Min 6.2C Rain nil]. Similar on the 8th, again no cloud at 0900 GMT, but breezier. Very good visibility with slight smoke haze. Very fine and sunny (Castlederg 19.5C Porthmadog 18.6C Tiree 15.1h Aberdaron 14.6h) [Max 13.4C Min 6.1C Rain nil]. Very fine and sunny on the 9th with a light ENE'ly breeze, good, moderate haze [Max 12.8C Min 3.9C Rain nil].

Hardly a cloud on the 10th, moderate visibility with moderate haze. Very fine and sunny, S'ly breeze later backed NE'ly, intermittently SW'ly. The soil is now very dry and there are cracks of 2 to 3 mm in undisturbed places. Soil moisture, 2 - 8 cm under grass sward, gravimetrically determined today was 41% dry mass; the top 2 cm of grass and root mass contained 67% moisture. On the met plot where there is no grass and soil is undisturbed moisture was down to 16.8% dm close to the permanent wilting percentage of the local soil which is 15.2% dm. On the vegetable plot that has been worked, but not irrigated, the moisture content at the surface was 19.8% dm. We could do with some rain! (Sheffield 19.8C Braemar -3.8C Kinlochewe 6.4 mm Wattisham 14.5h) [Max 15.2C Min 4.3C Rain nil].

A very fine and warmer morning on the 11th with few clouds. Pressure had fallen to 996 mb with a thundery low developed 990 mb near Cap Finisterre with thunderstorms breaking out in France, S England and S Wales during the day. The temperature at Gorddinog AWS rose to 21.0C and 20.3C at Gorwel Heights. Here it become cloudier in the afternoon with a maximum of 19.1C; we had slight showers in the evening and again after midnight, not enough to dampen down the dust. Tree bumblebee on Bugle flowers in the garden. We have seen tree bumblebees, new in the UK this century, in the garden the last 2 or 3 years; with the fine weather they are back and have been seen frequently on the Bugle Ajuga reptans on the rockery banks. Tree bumblebee nest on bluetit nest in nesting box. Last year they made a nest in one of the bird nest boxes. First recorded in Britain in Wiltshire in 2001, Scotland in 2013 and now Iceland and even within the Arctic Circle. Last year on emptying our nesting boxes at the end of the season we found that a blue tit nest had been taken over by tree bumblebees (right). The previous year they had nested in the eaves in an old sparrow nest! (Porthmadog 22.9C Usk No 2 17.8 mm Leeming 13.8h) [Max 19.1C Min 7.5C Rain 0.2 mm]. A dull, rather murky wet day on the 12th with poor visibility. Pressure was on 993 mb with low 990 mb over the Severn Estuary tracking slowly N to be 993 mb St George's Channel at noon and 995 mb Cardigan Bay at midnight. Rain here 1730 to 1930 GMT was moderately heavy, damped down the dust very nicely (Drumnadrochit 21.9C Gorddinog AWS and Gorwel Heights 18.6C, Scilly Is. 25.8 mm) [Max 16.0V Min 11.6C Grass 10.1C Rain 10.5 mm]. The 13th began dull and damp after the rain; there were signs of the cloud thinning and opening up with pressure 1002 mb rising. Very windy during the afternoon with strong gusts bending branches on the trees and tearing some off to litter the ground. Showers of rain came along in the evening (Weybourne 19.9C Lough Fea 18.0 mm Aberporth 7.8h) [Max 16.4C Min 9.3C 1.1 mm]. A bright and sunny day on the 14th, we still had a moderate to strong SSW'ly wind with pressure 1014 mb rising. Low 980 mb S Iceland had an occluded front moving eastward away from us giving a sunny, but breezy afternoon. Solar radiation was a high 27 .19 MJ m -2 with Valley 14.3h given the sunniest place in Britain (Heathrow 20.9C Upper Lambourn 16.6 mm Valley 14.3h) [Max 15.8C Min 9.0C Rain 1.6 mm]. With low 985 mb S of Iceland on the 15th there was an associated cloud mass over Britain and a warm front over the Irish Sea. The day began overcast with drizzle and rain, poor visibility and a moderate to strong SSW'ly wind. This situation resulted in some Föhn-enhanced AWS temperatures on the mainland in Llanfairfechan: Dwygyflchi 20.6C Gorwel Heights 20.0C; Gorddinog 19.3C; and Rhyl 19.1C demonstrating the local temperature microclimate. The MO UK maximums reported were 20.1C at Lossiemouth and Wales, Rhyl 19.1C. Capel Curig had a wet day with [65.2 mm] reported (Lossiemouth 201.1C Aboyne 1.5C Capel Curig 46.4 mm Aviemore 4.0h and Valley 0.0h) [Max 14.5C Min 10.0 Rain 17.2 mm].


The first 15-days had 30.6 mm of rainfall which was (42%) & [49%] of the monthly total averages. Temperatures had been a little lower than the monthly averages with the mean 11.4C (-0.1) & [-0.3].

The 16th began dull, wet and misty with drizzle and or rain that petered out during the morning. A mild 13.0C overnight and at 0900 GMT the temperature was 13.8C. Pressure was on 1016 mb with a large complex low pressure area 988/ 991 mb S of Iceland that covered the UK, Denmark Strait, S Norway and N Sea. High pressure was over SE Europe 1031 mb and Azores 1026 mb. In the afternoon the cloud cleared and there was sunshine (Gravesend 25.8C Hawarden 19.6C Capel Curig 38.6 mm Kirkwall 12.5h Valley 5.3h) [Max 16.4C Min 13.0C Rain 0.1 mm]. A cloudy and dull morning on the 17th with some thinner patches overhead and good visibility. Pressure was 1018 mb with the large complex low-pressure area to the NW 998 mb still dominating the scene with frontal bands traversing SE with showers following. It was not until the end of the afternoon that the cloud broke up to give some sunshine. A dry day (Langdon Bay 25.0C Braemar -1.9C Holbeach 40.4 mm Lerwick 14.1h Aberdaron 6.3h) [Max 14.3C Min 8.9C Rain nil]. The sky had cleared on the morning of the 18th giving a largely sunny morning with very good clear visibility. Pressure was on 1013 mb; the low-pressure area to the NW was filling, but still dominating the weather. Grass is growing quickly now at 8.0 g dry mass m -2 d -1 , a burst of spring growth related to flowering tiller production, and the total yield this year so far has reached 3.34 tonnes per hectare. Rain on the 15th had increasing soil moisture content to 58.6% dry mass gave a boost to growth; evaporation rates are just about balancing rainfall the PWB (potential water balance) being -0.4 mm, but the PWD (potential water deficit) indicated by lysimeter data on the 15th of the month was 23 mm [Max 15.8C Min 8.5C Rain nil]. ...

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Graph of daily mean temperature. Graph of daily maximum and minimum temperatures. Graph of soil temperature at 30 cm depth. Graph of daily rainfall. Histogram of monthly rainfall compared with the long-term average. Histogram of accumulated monthly rainfall with comparisons. Daily global solar radiation in Llansadwrn (midnight to midnight) Anglesey sunshine: Source of original data (provisional) SYNOP reports Valley Met Office. Graph showing net yield of a mown grass ecosystem at the weather station. Red graph is total yield; Green graph is rate of growth. Comparison of annual grass production since 2004. Histogram of potential evapotranspiration and water balance. Soil moisture percentage (% dry mass).


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Graph of daily mean temperature. Graph of daily maximum and minimum temperatures. Graph of soil temperature at 30 cm depth. Graph of daily rainfall. Histogram of monthly rainfall compared with the long-term average. Histogram of accumulated monthly rainfall with comparisons. Daily global solar radiation in Llansadwrn (midnight to midnight) Anglesey sunshine: Source of original data (provisional) SYNOP reports Valley Met Office. Anglesey hourly mean wind wind: Source of original data (provisional) METAR reports Valley Met Office. Graph showing net yield of a mown grass ecosystem at the weather station. Red graph is total yield; Green graph is rate of growth. Comparison of annual grass production since 2004. Histogram of potential evapotranspiration and water balance. Soil moisture percentage (% dry mass).


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Graph of annual mean temperature and anomalies 1979-2016. No. of winter air frosts in Llansadwrn. Annual rainfall anomaly at Llansadwrn 1929-2014. Anglesey annual sunshine anomaly 1931-2014. Number of days with gales recorded in December and January on Anglesey.


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Large [260 KB] NOAA 12 visible image at 1623 GMT on 8 April 2002 showing a cloud-free British Isles. Courtesy of Michael Wienzek ( A rare cloud-free image of the British Isles captured by the NOAA 12 satellite at 1623 GMT on 8 April 2002.

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