Llansadwrn (Anglesey) Weather Latest Diary

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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 30-y climatological average [currently 1971 - 2000]. All data are subject to verification and amendment.

It was the sunniest June since 1975. The 251.7 h of sunshine (142%) and [149%] recorded at RAF Valley was the 3rd highest on the Anglesey record (K&Z adjusted values). Rainfall here was 47.7 mm (75%) and [72%], lowest since 2006, brought rainfall for the first 6 months to 286.4 mm, lowest in Llansadwrn since 1929 (283.7 mm). Temperatures were above average with the mean 15.0C (+0.7) and [+1.4] of average, highest since 2006.

July

1st: There were spots of rain from 0745 GMT it having been previously dry. The sky was overcast at 09 GMT and there were still the spots of light rain. The rainfall radar showed a band of rain in N-S western parts and over Anglesey where amounts were patchy. Visibility was good, but cloud and mist hung around the mountaintops. Another windy morning the S'ly force 5/6 soon becoming force 6/7. The rain petered out and with the cloud thinning it was bright with occasional glimpses of weak sunshine. At 13 GMT the sky was still overcast, visibility was moderate and thickening cloud during the afternoon brought slight rain from 1500 GMT that continued into the evening with rain from 2000 GMT through to midnight.. The day was sunless. [Rain 7.4 mm; Max 20.5C; Min 14.5C; Grass 14.5C]
2nd: Rain continued until 0115 GMT and there was a further light shower at 0515 GMT. Before 09 GMT the sky began to clear with 4 oktas of cumulus some well developed. There was a fresh S'ly breeze pushing the clouds giving some sunny spells in-between. Although convection reduced through the morning orographic cloud lines developed, some were seen over the Menai Strait at Beaumaris (below). The afternoon was mostly sunny, less convective cloud although some thinner patchy cloud encroached later. Another windy day. [Rain 0.0 mm; Max 20.3C; Min 12.0C; Grass 10.9C]
3rd: A fine and sunny morning with just a few small dispersing cumulus clouds in the vicinity and a little cirrus. There were rain showers to the NW over Ireland and Scotland, but here it was mostly sunny with a deep blue sky. The SW'ly wind was force 3 and visibility very good. A line of cumulus clouds had developed over the mountains by noon. The afternoon was sunny, the temperature rising to 20.5C. Thin moderately high cloud passed over later in the evening, but cleared again by 21 GMT. [Rain trace; Max 20.5C; Min 12.0C; Grass 10.4C]
4th: Pressure had fallen to 1014 mb with low 990 mb off NW Scotland. The sky was overcast and the near gale force SSW'ly wind was soon touching force 8 bending the trees and tearing off green leaves leaving a scattering on the ground. Capel Curing had reported a mws of 47 mph at 07 GMT and Valley 40 mph at 10 GMT. FirstHydro Clogwyn AWS reported mws of 60 mph and a gust of 85 mph at 09 GMT. Not a pleasant morning, not one to linger over the obs although opportunity was taken to tie back one of two plants and secure various garden furniture. There were spots of rain on the wind, but rain was heavy in Scotland. There was driving rain across the fields on a strong SW'ly wind during the early part of the afternoon, then there was a sudden clearance with sunny spells by 15 GMT. The wind moderated and the rest of the day was pleasant and mostly sunny. [Rain 3.0 mm; Max 19.4C; Min 13.0C; Grass 10.4C]
5th: A bright and sunny early morning, but cumulus clouds were increasing and cover was 6 oktas at 09 GMT. Pressure 1022 mb was rising under the influence of Azores high 1032 mb. Complex low-pressure (992 mb) was now to the N between Iceland and Norway and the associated cold front of yesterday was making its way through northern France. Pressure was also high 1018 mb over northern Africa. The wind was a light SW'ly and visibility good. Sometimes looking darker the cumulus clouds continued to pass over through the morning with brief sunny spells in between. The afternoon was a little sunnier for a while, cloudier again by 17 GMT. [Gravesend 24.7C, Hawarden 19.7C, Valley 11.0h] [Rain 0.0 mm; Max 19.1C; Min 10.5C; Grass 6.2C]
6th: An overcast and dull morning with a temperature of 15.9C (dewpoint 11.5C) at 09 GMT. Pressure was 1025 mb in a ridge 1029 mb over S Britain and Brittany, but low 975 mb was S of Iceland with associated frontal cloud affecting the north-west. There was little in the way of brightness in the afternoon in warm sector air with showery rain from 1830 GMT and the SSE'ly breeze freshening to force 6 by 2100 GMT as the cold front approached. [Coningsby/ Heathrow 23.8C, Capel Curig 12.2 mm, Valley 0.8h] [Rain 4.0 mm; Max 17.9C; Min 10.8C; Grass 7.2C]
7th: At midnight the low was 971 mb S of Iceland and pressure had fallen to 1015 mb. At 0430 GMT there was a heavy showery of rain (3.4 mm) on the weak cold front. The morning was again overcast and dull with a fresh to strong S'ly wind. Mostly dry with low cloud and poor visibility at first; after a little slight rain at 1130 GMT the sky began to clear and visibility improve around 1400 GMT giving some sunshine. Cloud increased again during the evening. [Paris 36C, Coningsby 25.4C, Valley 3.1h] [Rain trace; Max 19.6C; Min 14.0C; Grass 13.4C]
8th: A fine and bright morning and as cloud decreased becoming mostly sunny with 3 oktas cover at 09 GMT. With low 985 mb SE Iceland pressure here was 1017 mb. The temperature had risen to 16.7C and this was to rise to 19.8C during the afternoon before cloud encroached bring some light rain by 2030 GMT turning to drizzle later. [Paris 37C, Gravesend 28.5C, Hawarden 22.6C, Valley 3.5h] [Rain 3.3 mm; Max 19.8C; Min 12.9C; Grass 11.5C]
9th: A spell of light rain from 01 GMT and intermittent slight rain or drizzle turning heavier again before 09 GMT. With a frontal-wave moving in from the West light rain or drizzle continued through the morning with poor visibility. From 1440 GMT there was moderate to heavy rain this continuous through until 2100 GMT. A sunless day. [Paris 36C, Gravesend 31.7C, Manston 28.9C, Hawarden 23.3C, Capel Curig 30.6 mm] [Rain 18.8 mm; Max 17.9C; Min 12.7C; Grass 12.4C]
10th: Further light to moderate rain from 02 GMT until just before 09 GMT when 18.8 mm of rain was measured over 11.3 h during the 24-h period 09-09 GMT. The morning was overcast under slow-moving frontal cloud with slight rain at times on a moderate S'ly breeze. A trace of reddish-brown Saharan dust was deposited in the showery of rain. Trajectory analyses using the HYSPLIT model (left), courtesy of the NOAA ARL Website, indicated that the dust probably came from a pool of dust circulating in mid-Atlantic around the Azores derived from dust storms in north Africa; the example at 1300 GMT shows trajectories arriving over Llansadwrn between 500 and 2000 m AGL today. The afternoon continued overcast with further showery rain falling from 2115 GMT. In SE England and W France it was sunny with temperatures over 30C. [Paris 30C, Gravesend 30.9C, Hawarden 26.2C, Capel Curig 11.4 mm, Valley 0.2h] [Rain 3.2 mm; Max 20.4C; Min 15.8C; Grass 15.7C]
11th: Still cloudy at 06 GMT, but soon with a clearing sky there were spells of sunshine at 09 GMT continuing through into early afternoon. Pressure here was 1014 mb and with low 996 mb was off N Scotland we were in a weak ridge of high-pressure. A mass of frontal cloud associated with low 1001 mb off Lands End began to encroach by 1500 GMT leading to an overcast evening. [Paris 36C, Gravesend 28.7C, Hawarden 20.1C, Valley 6.7h] [Rain trace; Max 19.0C; Min 11.6C; Grass 6.6C]
12th: A cloudy and dull morning with slight rain at 0730 GMT odd spots continuing up to 09 GMT. Pressure was 1015 mb and cloud was well above the mountaintops and the morning slowly brightened. The afternoon kept mostly cloudy, but there were some bright spells as the cloud thinned. Winds, generally E'ly, were light and visibility very good. [Paris 34C, Charlwood 24.0C, Valley 19.5C & 4.1h] [Rain 0.0 mm; Max 17.6C; Min 11.1C; Grass 7.9C]
13th: Cloud cover was decreasing with some mountain summits in the clear and at first the morning was bright with sunny spells. Overnight the minimum was air was 10.9C and on the grass the temperature had dropped to 6.8C. The temperature at 09 GMT was 17.3C (dewpoint 11.9C), visibility good. Pressure had fallen to 1009 mb and cloud as lows to the SW 995 mb off SW Ireland and 1005 mb Bristol Channel approached thickening cloud encroached. The afternoon and evening were overcast and dull. [Manston 23.0C, Capel Curig 13.2 mm] [Rain 8.9 mm; Max 20.6C; Min 10.9C; Grass 6.8C]
14th: The sky was overcast at 06 GMT and soon there were heavy showers of rain with 8.9 mm collected in the raingauge. The sky was clearing with cumulus and cirrus overhead at 08 GMT although cloud still hugging the mountaintops. Pressure had fallen to 999 mb with low 991 mb off SW Ireland and a cold front stretching across Anglesey to Brittany. Another shower at 09 GMT then a few sunny spells. It was to be a day of sunshine and showers, heavy at 1100 GMT and 1315 GMT. At 1545 GMT thunder was heard and with cumulonimbus clouds seen to the S heavy thunder again at 1605 GMT. At 1735 GMT with dark cumulonimbus to the SE of the station thunder was heard and a bolt of lightning reported striking the mountains above Llanfairfechan near the Roman Road. A few more sunny spells came along during the evening. [Holbeach/ Marham 23.5C, Redesdale camp 35.8 mm, Capel Curig 28.4 mm, RAF Mona 23.0 mm, Valley 2.6h] [Rain 14.0 mm; Max 19.0C; Min 13.0C; Grass 8.9C]
15th: St Swithin's Day: Light showers of rain dying out with just a few spots on the window just before 09 GMT. The sky was still overcast and the morning dull. Pressure was 996 mb with low 991 mb near Aberdeen, Scotland. The was a mass of cloud, associated with a rapidly developing low SW Ireland, was heading our way. Soon brighter with sunny spells by 1115 GMT the remaining cumulus clouds scudding along rapidly on the fresh SSW'ly. By afternoon the sky was cloudier and the wind had freshened to force 6/7 and branches of trees heavy with leaves were bending in strong gusts. Bright again with the odd sunny spells, still windy but dry, at 1500 GMT. There were a few spots of rain at 1730 GMT the sky soon overcast. At 1800 GMT the wind had moderated a little, but with pressure soon starting to fall the wind picked up again backing SE'ly, freshening to near gale to gale force 8, and rain turned moderate to heavy by midnight. [Rain 11.6 mm; Max 18.4C; Min 13.2C; Grass 11.2C]

Making up for the dry start to 2010 the first 15 days of July had 74.2 mm of rain (99%) and [117%] of average. The mean temperature was 15.9C (+0.1) and [+0.3] of the average for the month.

16th: At midnight pressure had fallen to 987 mb and the wind strengthened to force 7/8. At 01 GMT the wind backed SW'ly and increased to unseasonably force 8/9 with very strong gusts. Storm force 10 winds hit many coastal areas of Lleyn and Anglesey; at Aberdaron a gust of 84 mph was recorded, 74 mph at Capel Curig and 71 mph at Valley where a mean wind speed of 55 mph (force 10) was recorded at 01 GMT On the summit of Snowdon some record extreme force 12+ mean wind speeds were recorded between 00 and 06 GMT, with gusts of 194 mph at 0255 and 0315 GMT. Equaling the unverified report of 194 mph on Cairngorm on 19 December 2009 (Daily Telegraph, 6 January 2009) 37 mph less than the world's highest gust on Mount Washington in 1934. The night was wild here with twigs and leaves being stripped from the trees and garden furniture overturned. In Llanfairfechan a trampoline was blown 30 m over a garden wall. Irish Sea ferries were unable to dock at Holyhead and damage was reported to boats in the Menai Strait and around the coast with several, including a fishing vessel, breaking free of moorings. At Barmouth there was an 0.7 m storm-surge on top of the high tide just before midnight (Courtesy of POL & National Oceanography Centre). There were several reports of fallen trees, a parked car in Llanfairpwllgwyngyll was badly damaged by a branch torn from a large ash tree, and broken power lines in Anglesey and Gwynedd. Roads over a wide area of SE Anglesey were littered with leaves and branches, mainly broken from ash trees that are particularly vulnerable to high-winds when fully leafed. At 09 GMT, still overcast, the wind had moderated and pressure 1001 mb was rising. By 0930 cloud was thinning and broken sky with sunny spells came along within the hour. The sky cleared some more in the afternoon, blue sky overhead, with a line of cumulus over the Snowdonia mountaintops. By 1630 GMT cloud had encroached; there was a shower of rain at 1715 GMT before the evening that was dry and less windy. [Rain 0.5 mm; Max 18.7C; Min 11.6C; Grass 11.8C]

It was the last, and open day, of a 3-week dig undertaken by volunteers and experts of the Gwynedd Archaeology Trust at Tai Cochion, Brynsiencyn . This important site with a preliminary date of 160 AD must rewrite the Roman history of Anglesey. The panorama photograph above (click to reveal, again to enlarge) shows the blackened remains of a one of at least 12 rectangular buildings 6.5 m wide (centre) on the large site, recently surveyed geophysically, close to the Menai Strait. The dig also revealed on the right of the photograph a 7.5 m wide 'Roman' road pointing in the direction of the Strait . On the left of the photo were found pits filled with broken pottery and 6 post-holes indicative of a raised granary store. Broken querns could be seen in the foundations . Pottery finds, still being excavated on the day , included pieces of reddish-brown Samian ware, black glazed from Poole Harbour in Dorset, and white, a flanged mortarium with the potter's stamp (a likely kitchen utensil used for grinding) . There was much discussion among visitors and experts as to how the 'township' developed, the construction of the buildings, its association with Segontium (AD 77 to 394) on the opposite bank of the Strait near Caernarfon, and what happened to it (charcoal deposits, possible fire) leaving it hidden under green fields and undiscovered until recently. The association may have included export of grain and other produce from one of the sunniest and warmest parts of the island with productive brown-earth soils, by boat the short distance across the Strait.

18th: A frontal-wave moved across the Irish Sea at midnight bringing moderate to heavy rain from 03 GMT with 15.3 mm collected in the rain gauge at 09 GMT. Overcast with low uniform grey stratus, poor visibility and heavy rain on a moderate SSW'ly wind. Rain, sometimes heavy, continued through the unpleasant sunless day. {Norwich 26.0C, Hawarden 22.8C, Capel Curig 59.8 mm, Manston 14.1h} [Rain 19.6 mm; Max 17.0C; Min 13.0C; Grass 11.9C]
19th: Intermittent light rain turned heavy after midnight until after 03 GMT when slight easing to drizzle or slight rain up to 09 GMT. With another 19.6 mm in the raingauge the total for the month had risen to 109.6 mm not yet reaching the 135.8 mm of last year, or the 120.4 mm of 2008. Already the 15th wettest July since 1928 and, given a few more days of this weather, who knows? Pressure was 1019 mb with high-pressure to the S over SE England and France, while low 998 mb was W of Ireland with associated slow-moving fronts with embedded pockets of heavy rain persisted in the north-west. For about 20 minutes at 09 GMT the cloud thinned and it was brighter, the cloud soon thickening again ensured another sunless day with light rain or drizzle becoming heavier after noon and continuing through the evening. [Heathrow 29.5C, Hawarden 24.6C, Shap fell 40.4 mm, Capel Curig 31.6 mm, Manston 12.4h] [Rain 20.2 mm; Max 17.0C; Min 15.2C; Grass 15.0C]

¤

20th: It stopped raining at 0500 GMT, after a cold front had passed, but there had been a few spots in showers up to and including 09 GMT. The rainfall total had reached 129 mm 204% of the 30-y average. Cloud had been moderately high, over the mountaintops, but lowered as some more rain-bearing stratiform cloud moved across. Later lifting again and I spotted a patch of blue sky to the NW at 1040 GMT, but it soon disappeared. More spots of rain and a light shower just before noon. There was moderate to heavy rain from 1800 GMT to 2130 GMT. [Hawarden 20.7C & 68.2 mm, Lake Vyrnwy 43.6 mm, Rhyl 30.4 mm, Blackpool AP 26.8 mm, Capel Curig 14.2 mm, Dyce 10.8h] [Rain 5.9 mm; Max 16.4C; Min 12.9C; Grass 12.6C]

On the beach in Aberffraw Bay there was evidence of some oil pollution. A line of patches of 'chocolate mousse' an oil/ water emulsion stretched all across the beach on the incoming tide at 1400 GMT. Further up the beach were several black bands and the occasional blob of tar washed in on previous higher tides . Examination of the black deposits showed they were oil covered sand grains: A sample vigorously shaken in a test tube with water cleaned the sand grains, that sank to the bottom, leaving coloured water above with a foamy chocolate coloured emulsion on the sides of the tube. Possibly a new pollution incident or, as a result of the storm on the 16/17th, disturbance of the wreck of the M.V. Kimya that sank in January 1991. The Kimya was carrying a cargo of sunflower oil and there would have been some fuel oil aboard. The beach was strewn with seaweed and mussel shells while there were a number of detached large fronds of Laminaria in shallow water effects of the storm. Most of the seaweed was high on the beach, from high spring tides on 12/14th, but no oil deposits were seen at the high tide mark

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Last month's diary Diary since January 2010 Daily Observations, usually updated bi-monthly Monthly summary and further analysis of the observations in 2009 Snowdonia snowline for 2009/2010, 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 2009 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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