Llansadwrn (Anglesey) Weather

Latest Diary Tenth Year

April

16th: Frozen dew on the grass persisted after sunrise until just before 09 GMT in shady places. The sky was mostly clear, but for here there were an unusual number of contrails drifting across with an E'ly air flow. Pressure 1021 mb was falling with high-pressure 1027 mb over the North Sea and S Norwegian Sea and low pressure 979 mb S of Greenland. Cloud did increase during the morning, but mostly cleared in the afternoon with the temperature rising once again to 13.2C in a light E'ly breeze. Solar radiation of 23.20 MJ m^-2 was highest of the year so far. The evening was clear, but there was no frost. [Rain trace; Max 13.2C; Min 1.2C; Grass -3.1C]
17th: Cloudier after midnight and a slight shower of rain at 0745 GMT hardly wetted the ground and was unmeasurable. Pressure 1012 mb continued to fall with the high 1026 mb N Scotland and S Norwegian Sea with low 988 mb on an occluded front off the Bristol Channel to the SW. The morning was mostly cloudy with the odd bright spell. Visibility was just good (10 km) obscured by moderate smoke haze. The afternoon was sunnier with the cloud mostly clearing and the temperature rose to 10.7C, moderated by the moderate to fresh E'ly. The evening was mostly clear. [Rain 0.0 mm; Max 10.7C; Min 3.1C; Grass 1.8C]
18th: Overcast with low stratocumulus clouds, sometimes looking dark. Visibility was good with moderate smoke/dust haze. No frost again overnight and the grass dry with the soil surface looking drier too. The moisture content is currently an average 66% of dry mass, down from 75% a month ago. Parts of the garden are drier (58%) and some still very wet (76%). Pressure 1002 mb was falling with complex low-pressure 975 mb over the Bay of Biscay and high 1024 mb SE Iceland. In between we were experiencing the easterly air flow (force 4 to 5) resulting partly in the poor air quality with moderate levels of pollutant ozone, and suspended dust. The morning kept cloudy with moments of brightness as the cloud thinned revealing an obscured sun. The afternoon was overcast with patches of brightness seen sometimes over the mountains where snow persisted, but visibility improved. The evening and night were similarly cloudy, dry and windy. [Rain 0.0 mm; Max 9.0C; Min 2.9C; Grass 1.2C]
19th: Little had changed in the synoptic situation, we still had the ENE'ly wind at force 5 with pressure low to the S (991 mb Channel) and high 1021 mb Iceland. Pressure here 1001 mb was rising and the temperature at 09 GMT 6.8C, dewpoint 3.8C. An occluded front was lying from S Ireland through Wales to E Anglia and the sky was overcast and the day sunless, just to the N in Tiree Is there was 13.6 h of bright sunshine. The surface soil continued to dry, the tops of mole hills were dry with undisturbed soil on the observation plot almost dry. Evaporation over the past 5 days has been 8.4 mm measured by the Piche evaporimeter. [Rain 7.9 mm; Max 9.1C; Min 5.5C; Grass 4.5C]
20th: There was light to moderate rain from midnight until 0730 GMT then drizzle. It was a very murky morning with further fine drizzle and the odd spot of rain. The occluded front had moved a little N and was over Anglesey and Merseyside. Pressure was 1005 mb and the wind still force 4 ENE'ly. The slight drizzle and spots of rain continued in the afternoon without wetting much even when you were out in it. The temperature rising from a minimum of 5.5C struggled to reached 8.3C during the day and falling to 5.5C again overnight. In parts of S England temperatures soared reaching 18.6C in the Solent, even Pembrey Sands had 14.8C. Stornoway was sunniest with 13.0h sunshine duration. The 3rd sunless day with solar radiation of 5.36 MJ m^-2 lowest of the month and since 20 March ! With the frontal cloud drifting N and fragmenting the evening was drier and by midnight the full moon was seen in a hazy sky. {Solent 18.6C, Lake Vyrnwy 3.7C (day 6.2C, Stornoway 13.0h} [Rain 0.2 mm; Max 9.2C; Min 5.5C; Grass 4.8C]
21st: A bright hazy morning, the first for 3 days, with some sunshine breaking through cirrus clouds (6 oktas cover). We still had the E'ly wind, force 4, but pressure 1009 mb was rising with high 1023 mb Norwegian Sea and complex low 993 mb N France. There were some patches of snow still to be seen on the mountaintops. The morning was sunny with the temperature at 09 GMT 9.2C the maximum of the past 24-h. The afternoon had further hazy sunshine with visibility deteriorating from moderate to poor and temperature rising to 12.3C. {Hawarden 15.2C, Stornoway 12.0h, Valley 5.8h} [Rain 0.0 mm; Max 12.3C; Min 5.5C; Grass 4.1C]
22nd: A clear sky morning with hazy sunshine, but poor visibility with dust high in the atmosphere. Pressure was 1010 mb and there was a light NE'ly breeze. Our first swallow was seen near Llanbedrgoch on the way to Cors Goch where grasshopper warblers were heard singing like sewing machines across the mire. The mire itself was still looking very brown with standing died back reeds yet to begin this season's new growth and the boardwalk was flooded with several inches of water . Some of the trees were beginning to look green and some wood anemones were seen in woodland . The afternoon was sunny and in a light variable, but sometimes SE'ly, breeze off the mountains the temperature rose to 19.2C, highest of the year so far. The evening was clear with pipistrelle bats around at dusk, but encroaching frontal cloud was seen in the west.{Southampton 20.7C, 11.4h, Trawsgoed 18.7C, Fair Isle 8.7C} [Rain 1.2 mm; Max 19.2C; Min 5.3C; Grass 3.2C]
23rd: There was light rain between 01 and 02 GMT and at 0630 GMT thick fog with visibility only 100m across the fields. At 0800 GMT the cloud started lift and with visibility 4 km the sun began to break through. At 09 GMT pressure 1015 mb was rising; there were 6 oktas of mainly cumulus clouds, but visibility was restricted by low cloud and mist on lower slopes of the mountains. By 11 GMT there were just 3 oktas cover of cumulus clouds and very good visibility. A few more bluebells have opened over the last few days and sycamore leaves are expanding rapidly, but there is no sign of leaves on beech or ash. Flowers on the wild cherry were opening this morning, trees in sheltered locations at sea level have been in flower for about a week. The day became mostly sunny, but windier in the afternoon the SW'ly reaching force 4/5. The sky was almost clear later just before frontal cloud encroached. {Hawarden 16.6C, Aberporth 9.9h, Valley 9.0h, Milford Haven 7.3 mm} [Rain 3.1 mm; Max 16.0C; Min 8.0C; Grass 5.9C]
24th: There was rain between 0315 and 0345 GMT on a gusty cold front then showers around 05 GMT before starting to clear. At 09 GMT the S'ly wind was force 5 and pressure 1015 mb was rising and the day became mostly sunny with solar radiation of 24.60 MJ m^-2 and 9.9 h sunshine duration recorded at RAF Valley. {Hawarden 15.4C, St Athan 10.5h} [Rain 0.1 mm; Max 14.9C; Min 8.0C; Grass 5.9C]
25th: It was a damp and grey morning setting the scene for the day. Soil temperatures down to 1 m were all 10C, or more, for the first time this year. This notable event occurred on 9 April 2007 and on the 21st in 2006. It was dull with slight rain at times m most between 1730 and 1830 GMT, the day was sunless. The evening and night were drier, but rather windy. [Rain 2.0 mm; Max 12.6C; Min 7.6C; Grass 4.8C]
26th: The overnight air minimum temperature of 9.7C was highest of the month. A little brighter this morning with a hole in the cloud sheet. The cloud 7/8th comprised mainly moderately high altostratus with under layers of altocumulus and cumulus. Pressure 1020 mb was rising and the afternoon had good visibility with some brighter spells developing, but remained sunless. [Rain 4.0 mm; Max 13.4C; Min 9.7C; Grass 8.4C]
27th: At midnight frontal cloud stretched from W of Iberia through St George's Channel and Irish Sea to Norway, associated with low 987 mb over the Norwegian Sea. At 09 GMT pressure 1014 mb was falling slowly in a slack pressure area and it was calm. It was one of those mornings that had Anglesey enveloped in low cloud and mist. There was 100% relative humidity and visibility very poor, 1 km. All thermometers in the screen were reading 9.8C, as they should after resetting the maximum and minimum. It was calm and a good time to check that all were reading the same and agreeing with the NPL certificated thermometer. With 100% RH the dry and wet bulbs read the same, in fact they were all acting as wet bulbs. Blackbirds and thrushes were singing, the males having little to do at the moment with females sitting on eggs. There was little change until late in the afternoon when the sky brightened from the W and some sunshine broke through by 16 GMT, but it did not last long and the evening was dull once again. With the morning very dull, despite a little sunshine, solar radiation was 7.02 MJ m^-2 2nd lowest of the month. The evening turned cloudy again and there was a moderate shower of rain from 2230 GMT and continued showery through the night [Rain 8.9 mm; Max 12.0C; Min 9.5C; Grass 8.9C]
28th: Overcast with slight rain up to 09 GMT. Pressure 1001 mb was falling with low 997 mb over the Norwegian Sea and frontal wave low 995 mb off NE Scotland. The showery trough over Anglesey and N Ireland was just starting to move away. There were puddles of water around the garden and visibility moderate in rain and mist. A blackcap and chiffchaff were singing strongly in the trees. By afternoon the sky was clearer and there was plenty of sunshine and clear visibility. Snow patches on the mountains are now confined mainly to the NE flank of Carnedd Llewelyn. The evening was clear and on the grass the temperature went down to 0.6C. [Rain 1.3 mm; Max 12.7C; Min 6.5C; Grass 3.3C]
29th: A sunny morning with a light NE'ly breeze. Visibility was very good >50 km affording fine views of mountains and Lleyn Peninsula. Pressure 996 mb was falling within complex low-pressure with low 992 mb to the N of Scotland and low 988 mb over the Celtic Sea. Pressure was high 1024 mb over Finland and W Russia. During the day the low moved over SW England and brought rain, on an occluded front, there and to South Wales with Milford Haven recording {30.4 mm}. The morning here was mostly sunny then cloudier by noon. The afternoon had some good sunny spells before showery rain developed around 1500 GMT. As the front moved N there was moderate rain from 2200 GMT. {Crosby 16.3C, Valley 13.8C, Tiree Is 12.9h, Valley 9.5h, Milford Haven 30.4 mm}[Rain 10.5 mm; Max 13.5C; Min C; Grass C]
30th: With the low 986 mb at midnight slow-moving over SW England moderate rain continued until 0400 GMT. By morning there was a fresh fall of snow on the mountains above 2700 ft. It was a dull morning, although pressure 988 mb was rising and the slight rain eased by 11 GMT the morning remained dull. The afternoon had further slight rain from 1500 to 1930 GMT and the day was sunless with the temperature rising to only 7.7C. Before midnight there were a few holes in the cloud sheet. [Rain 2.4 mm; Max 9.2C; Min 6.0C; Grass 5.5C]

The month ended with a rainfall total of 86.2 mm (110%) and [149%] of the monthly averages. The mean temperature was 8.3C (-0.8) and [-0.3], the mean maximum was 11.9C [(-0.9)] on both averages while the mean minimum was 4.7 (-0.8) but [+0.3] of the 30-y average. Sunshine duration at Valley was 168.2 h (105%) [107%] K&Z adjusted averages.

May

1st: A cloudy morning with 1 or 2 blue patches appearing as the cloudbase lifted. The temperature at 09 GMT was 8.7C and had just been on 9.2C, the maximum of the past 24-h. Pressure 1001 mb was rising and visibility was good. There were sunny spells in the afternoon with the sky clearing over Anglesey leaving a line of stratocumulus clouds over the mountains of Snowdonia, similar views can be seen left (across a field of cattle) and right (across a field of sheep). Take your pick! [Rain 2.7 mm; Max 14.2C; Min 4.8C; Grass 1.7C]
2nd: There were showers of rain from 05 GMT that accumulated 2.7 mm by 09 GMT. With 6 oktas of cumulus clouds the morning began brightly with a gentle S'ly breeze. Pressure 1017 mb was rising slowly; the temperature was 11.3C, dewpoint 7.6C, and visibility was very good >30 km. Pressure was high 1024 mb to the SE over central Europe and low 987 mb W of Iberia with trough to W of Ireland giving us a S'ly flow of air. Another mostly sunny day with mainly cumulus clouds and an increasing amount of cirrus in the afternoon. Later the cumulus decreased and the evening was mostly sunny. [Rain 0.0 mm; Max 15.6C; Min 6.1C; Grass 2.3C]
¤ 3rd: A bright morning with 6 oktas cover of altostratus and altocumulus clouds. The blue of the sky was looking milky as there was suspended Saharan dust high in the atmosphere. Pressure was 1019 mb with high 1030 E North Sea and low 978 mb W of Ireland. The wind was light to moderate SE'ly and cloud tended to burn off giving some long spells of sunshine. The temperature reached 21.1C, highest of the year so far, in a Föhn-like wind with the relative humidity a low 48%, but observer Keith Ledson at Red Wharf Bay recorded 23.1C just before a sea breeze set in. Evaporation by Piche evaporimeter was 5.3 mm in the 24-h 09-09 GMT. It was a warm sunny evening, later there were some spots of dusty rain. [Rain trace; Max 21.1C; Min 8.6C; Grass 6.0C]
4th: Overcast with moderately high mainly altostratus cloud. It had been a warm night with the air minimum not falling below 15.4C, second highest in May and highest this early in the year since before 1979 (17.0C on 17 May 2002). There had been a slight deposition of light reddish-brown dust associated with initially with dry deposition including pollen and then a few spots of rain. In previous days deposits have been greyish (grime) with yellow (pollen). At 0900 GMT pressure 1017 mb was rising and the temperature was 17.7C, dewpoint 11.1C. There were a few more spots of rain and dust from 0915 GMT and the morning kept overcast. There was further moderate rain in the afternoon as 2 cold fronts passed over before brightening up soon after 1500 GMT. Further light reddish-brown dust (MUNSELL ® 5YR 7/3) had been deposited in the rain without much pollen. Trajectory analysis, using the HYSPLIT model at the NOAA Air Resources Laboratory, indicated that parcels of air arriving over Llansadwrn at 15 GMT had come from a pool of N African dust around the Canary Islands. Soon after the sky cleared rapidly giving a sunny end to the day. [Rain 8.3 mm; Max 18.8C; Min 15.4C; Grass 12.2C]
5th: An almost clear sky except for a little cloud well south of the Snowdonia Mountains. Noctilucent clouds were seen for the first time this season in Northern Ireland at 03 GMT, too early for me. Mist was blowing across fields from sea fog in the Irish Sea and Red Wharf Bay penetrating Malltraeth Marsh and Afon Nodwydd valley, but here up on the Llansadwrn ridge were were in sunshine. Pressure 1027 mb was rising and the day was sunny, but there was a cool NE'ly off the sea and this kept the temperature down to 15.5C. Later in the afternoon some cumulus clouds were seen over the mountains. An orange tip butterfly was seen around the garden and the first red admiral, possibly arrived here on the S'ly winds that brought the dust yesterday. Solar radiation was 26.84 MJ m^-2 and Valley recorded 9.4 h of sunshine. {Capel Curig 19.7C} [Rain 0.0 mm; Max 16.5C; Min 6.7C; Grass 2.8C]
6th: The morning had hazy (with dust and smoke) sunshine with 5 oktas of cirrus clouds. There was a light ENE'ly breeze and the temperature at 09 GMT 16.5C had exceeded yesterday's daytime temperature. Pressure 1024 mb was falling with high 1031 mb E North Sea and low 989 mb W of Ireland. There was a clear sky most of the day, some convergent cloud developed over the station for a while, but the S'ly won and the temperature reached 24.1C with relative humidity falling to 42%. The temperature, exceeding any last year, was the highest recorded since 21 September 2006 with 26.2C. Soil moisture determined today was 67% dry mass, a little drier at just below the saturated water level of 70%. The evening and night were mostly clear. [Rain 0.0 mm; Max 24.1C; Min 11.1C; Grass 7.3C]
7th: A fine sunny morning with smoke and dust haze. Pressure was 1020 mb and there was a light ENE'ly breeze. A cloudier day, with some weak convective clouds seen mainly to the W and S. Here the battle between the cool NE'ly off the sea and warmer S'ly air took place over the weather station in the afternoon. The effect was variable, the cloud coming and going , but the S'ly held long enough for the temperature to rise to 25.0C, highest so far. To mark the occasion the local flock of house martins were seen and heard chattering overhead for the first time this season. Our complement of migrating birds is nearly complete, only the spotted flycatcher is missing, but with declining numbers in recent years we will be lucky to see one. There are tiny goldcrests and goldfinches about the garden nesting somewhere in the shrubs and trees. It was a warm mostly clear evening with bats flying at dusk, a light shower of rain was reported in Llanfairfechan associated with some showery rain in S Snowdonia. [Rain 0.0 mm; Max 25.0C; Min 11.5C; Grass 8.3C]
8th: More of the same, almost clear sky and sunny with 21.0C at 09 GMT. A little cloud during the afternoon at times and with gusty S'ly breeze the temperature rose to 25.1C. By 1800 GMT frontal cloud, associated with low 998 mb W of Ireland, was seen encroaching. {Kinlochewe 25.3C, Valley 24.9C} [Rain 0.2 mm; Max 25.1C; Min 15.1C; Grass 10.9C]
9th: There was a shower of light rain at 0300 GMT that left paths damp in places in the morning and another deposition of the fine north African reddish-brown dust. There was also local gritty dust and tree pollen that is now appearing in increasing amounts. An overcast sky with poor visibility and a slight S'ly breeze at 09 GMT. The temperature was 14.8C and with 5 cm depth soil temperature of 16.0C soil and concrete were dry. Pressure was 1012 mb in a slack area over Britain with decaying frontal cloud over the west. The day was sunless and very dull but kept dry. Early purple orchids are flowering, the example right was found growing on a roadside in Anglesey. [Rain 0.0 mm; Max 17.2C; Min 13.4C; Grass 12.1C]
10th: Little change although pressure 1018 mb was rising. We still had moderately high frontal cloud overhead, stretching from Lands End to Cape Wrath. Soon after 0900 GMT there were some spots of rain and the radar was showing patchy rain over parts of South Wales and the west. The cloud was a little thinner and it was brighter during the day, but visibility was poor in the haze. By afternoon the sun was breaking through and there were sunny spells before evening. It was sunnier and a lot warmer in SE England. {Hertsmonceux, Sussex 27.3C, Valley 17.6C, Sennybridge 10.2C, Norwich AP 15.1h} [Rain trace; Max 18.5C; Min 11.2C; Grass 10.6C]
11th: Some clearer sky overnight and dew on the grass by morning. It was bright with mostly high cirrus clouds the front having moved westward. Pressure 1021 mb was rising and the temperature at 09 GMT was 15.7C in a light NE'ly breeze. Visibility was just good in smoke and dust haze with north African dust and photochemical smog. [Rain mm; Max C; Min 10.6C; Grass 8.2C]

Last month's diary Diary since January 2008 Daily Observations, usually updated bi-monthly Monthly summary and further analysis of the observations in 2008 Monthly summary and further analysis of the observations in 2007 Snowdonia snowline for 2007/2008, usually updated twice weekly in season The observer's choice of forecasts, satellite imagery and more Temperature graphs, daily and monthly rainfall histograms, accumulated rainfall total and more, all on a page for 2008 The Observer's Wx Bookshelf Location map and satellite image (use mouse, left click and hold to drag the image) 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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