Llansadwrn (Anglesey) Diary 2021

             

• January
• February
• March
• April

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 [1991-2020]. All data are subject to verification and amendment.

January 2021

Wales was under COVID-19 tier four Lockdown.

January 1 - It was a bright start to the new year after overnight ground frost (-2.7C on the grass) with a light NNE'ly breeze. The 4.1C temperature at 0900 GMT for the obs did not feel too cold. Decided to continue the observations so here's hoping it will be a drier year than last with plenty of sunshine. Pressure 1015 mb was rising with Atlantic-high 1032 mb to the SW. Altocumulus and cumulus 3 oktas were increasing with in particular cumulus developing to the west over the Irish Sea. There was snow on the Snowdonia Mountains lying at 1500 ft on the N-facing slopes of the Carneddau that I monitor, with remnants as low as 500 ft elsewhere. .Brief sunny spells in the afternoon (Scilly 8.2C Scolton 7.6C, Larkhill -7.3C Sennybridge -5.8C, Fylingdales 24.2 mm Rhyl 2.0 mm, Katesbridge 6.2h Aberdaron 2.2h Valley 1.5h) [Max 5.7C Min 0.1C Grass -2.7 Pptn 4.0 mm]. It was a wintry morning on the 2nd with a mixture of ice pellets (0522 GMT) followed by snow pellets and snow at 0830 GMT. The sky was overcast with a uniform grey cloud sheet and visibility was poor. It had been cold enough on the ground for water to freeze in troughs kept for birds, but there had been no air frost. The morning brightened and there were glimpses of sunshine through to the afternoon (Scilly 7.7C Scolton 6.4C, Eskdalemuir -7.9C Swyddffynnon -5.4C, Loftus 18.0 mm Aberdaron 4.6 mm, Dundrennan 6.2h Valley 4.0h) [Max 4.8C Min 0.8C Grass -4.0C Pptn 0.8 mm].

A fair morning on the 3rd with a light NE'ly breeze that strengthened during the morning. Mostly cloudy with not a lot of sunshine, but dry (Scilly 7.3C Scolton 6.5C, Loch Glascarnoch -9.1C Trawsgoed -2.6C, Chillingham Barns 18.2 mm Tredegar 7.2 mm, Tiree 5.9h Aberdaron 4.9h Valley 0.8h) [Max 4.8C Min 1.2C Grass -0.7C Pptn 0.1 mm]. On the 4th in good visibility there was a sprinkling of fresh snow on the summits of the Snowdonia Mountains. The snowline remains at 1800 ft, above this line, that I observe each day, snow cover must be 50% or more. I estimated that there was a 30% cover above 1750 ft with some snow as low as 1000 ft near Cwm Idwal. A fine, but mostly cloudy day. About 10 sparrows are spending the winter in our garden this year. A few more than last year (Scilly 7.3C Scolton 6.2C, Loch Glascarnoch -8.5C Whitechurch -1.6C, East Malling 11.4 mm Sennybridge 0.4 mm, Tiree 6.0h Aberdaron 2.1h Valley 0.4h) [Max 4.6C Min 2.6C Grass -0.6C Pptn 0.1 mm]. No frost overnight, but the 5th began looking more wintry with snow showers moving across the mountain summits, but the 1800 ft snowline had not changed. Precipitation in sight was noted, we had recent light drizzle then a little rain, that's all. There was a trace deposition of coloured dust, the University of Athens SKIRON Model had forecast north African dust arriving from the east. A light reddish-brown coloured Saharan dust was deposited around 0900 GMT. Backward trajectory analyses using the HYSPLIT model, courtesy of the NOAA/ARL website, indicated that parcels of air arriving over Anglesey at 0900 GMT originated from over the borders of Algeria and Tunisia. The most likely red route arriving at 4000 m AGL having taken an interesting and most unusual route over the Mediterranean, countries of south-east Europe, the Black Sea, Russia, the White Sea, north Finland (Lapland), the Gulf of Bothnia, southern Sweden, Denmark, the North Sea, northern England and the Irish Sea to arrive over Llansadwrn where it was washed out in rain. A fair day with a little sunshine at times (Magilligan 6.5C Usk 5.8C, Kinbrace -7.6C Tredegar -0.7C, Charsfield 11.0 mm Sennybridge 0.4 mm, St Athan 5.7h Valley 3.2h) [Max 4.8C Min 2.8C Grass 0.3C Pptn tr].

A very fine and bright morning on the 6th with cumulus clouds in the vicinity. Pressure was on 1025 mb with an Atlantic-high 1033 mb lying to the SW with a ridge towards the UK. There had been a light deposition of a coloured dust transported here on the easterly winds. A cold front to the NW was expected to move SE later. A short peak of sunlight 295 W m ^-2 at 1307 GMT tempted me outside to examine and clean out the bird nesting boxes. There had been 13 nests in the 23 boxes we have in use, 70% of the boxes had been used in some way in the past year. Uses included overnight roosting by bats, and one had a live mouse in residence making use of the nesting material (Ballywatticock 6.7C Scolton 6.0C, Loch Glascarnoch -12.3C Gogerddan -3.1C, Kenley 12.6 mm Libanus 0.4 mm, Aberdaron 7.1h Valley 5.4h) [Max 4.8C Min 1.7C Grass -1.3C Pptn 0.1 mm].

It was a frosty morning on the 7th after clear skies at night with the moon rising over the mountains at 2130 GMT last evening. There had been heavy dew and this had frozen when the temperature on the grass dropped to -9.2C, lowest of the month. The fields were white with frost in the morning. There had been a fall of isolated star-like snow crystals, these evident on various surfaces including ice on water where they had been kept frozen. There was rime on the rims of the copper raingauge. The magic soon disappeared with freezing drizzle turning to slight rain when it all thawed. Snow was lying on the mountains above 1800 ft. We had heavy sleet from 1545 GMT falling at 15 mm/h at 1552 GMT (Scilly 8.0C Mumbles Head 5.8C, Redesdale Camp -9.5C Sennybridge -6.8C, Baltasound 12.6 mm Aberdaron 4.4 mm, Camborne 6.7h St Athan 5.0h Valley 0.2h) [Max 3.2C Min -1.8C Frost 14.7h Grass -9.2C Pptn 9.1 mm]. Dull and overcast on the 8th with poor visibility in rain and sleet. The ground was very wet with some standing water in places after 9.1 mm of precipitation. Atlantic-high 1036 mb was lying to the W of Ireland with a ridge to Scotland, pressure here 1020 mb was rising. There had been snow pellets since midnight, the temperature was 2.2C (dewpoint 1.5C) at 0900 GMT and there was good chance of more ice precipitation. This came along in the shape of large flaked snow at 0940 GMT that began settling on grass, but was melting. There was another snow shower at 1320 GMT. The day was sunless and with a maximum of 2.7C it was the coldest day of the month (Scilly 6.9C Milford Haven 6.0C, Loch Glascarnoch -8.2C Gogerddan -3.0C, Loftus 24.2 mm Scolton 10.8 mm, Aldergrove 6.4h Aberdaron 0.7h) [Max 2.7C Min 0.0C Grass -1.4C Pptn 9.1 mm]. Turning colder overnight it was a cold and frosty morning on the 9th with icy conditions with an air minimum of -2.2C the lowest of the month. Snow pellets had fallen, the ground was hard and covered with white frost and the Stevenson screen door iced and frozen shut. You don't get many mornings like this in recent years. The AWS reading was -1.4C and by the time the screen was opened at 1000 GMT the thermometer inside read -0.3C. It was sunny with a blue sky and calm with moderate misty visibility. It was still sunny at 1300 GMT, hen cloud encroached with spells of slight rain or drizzle (Stornoway 8.5C Trawsgoed 6.2C, Eskdalemuir -11.9C Capel Curig -5.2C, Kinbrace 18.0 mm Capel Curig 0.8 mm, Wattisham 7.0h Aberporth 6.7h ) [Max 4.6C Min -2.2C Grass -8.1C Pptn 0.2 mm].

On the 10th snow was lying at 450 ft on the lower slopes of the Carneddau Mountains due SE of the weather station. When clear enough I have a good view 'across the water' or even 'across the river' was an old local expression. Reports from the mountains indicated a 'lot of snow' had fallen Today visibility was moderate with mist, but lifting rapidly so I got a decent view. Warmer at 4.2C, 97% RH, and no ice precipitation of any sort, rising to 6.5C during the day. It was a very dull day with spells of light to heavy drizzle, not amounting to anything in the raingauge (Achnagart 8.7C Hawarden 7.5C, Okehampton -5.8C, Tredegar -5.5C, Resallach 23.8 mm Swyddffynnon 0.6 mm' Waddington 2.9h Hawarden 0.9h) [Max 6.5C Min -1.4C Grass -3.0C Pptn tr]. On the 11th we were into a warmer airstream off the Atlantic. With pressure low 989 mb Norwegian Sea and high 1031 mb off Cap Finisterre a mild SW'ly airflow was the result. Pressure here 1016 mb was falling and we had another dull sunless day. There had been a significant snowmelt in warm rain on the mountains, the snowline raised to 2000 ft. Spots of rain gave way to heavier rain during the afternoon (Leuchars 10.9C Rhyl 10.0C, Baltasound -4.1C Tredegar 2.9C, Achnagart 47.2 mm Bala 17.2 mm, Lerwick 1.4h Hawarden 0.4h) [Max 8.7C Min 4.2C Grass 4.5C Pptn 13.5 mm]. After two sunless days the sky was clearing quickly on the morning of the 12th, brighter and a little colder again. Pressure 1015 mb was rising quickly in a ridge from high 1020 mb Iceland. A low 981 mb over the Baltic had associated cold fronts moving S over the UK. It was sunny to the north and wet to the south A fair day. At 2200 GMT the NE'ly breeze veered SW'ly with falling pressure and rising temperature in warm sector Atlantic air (Exeter 11.1C Cardiff 10.2C, Tulloch Bridge -5.9C Rhyl 4.5C, Okehampton 25.8 mm Swyddffynnon 21.4 mm, Boulmer 6.2h Hawarden 3.8h) [Max 8.2C Min 4.4C Pptn 4.8 mm]. There was continuous light rain from midnight on the 13th through the night to 06 GMT when it became moderate for a while. At 0900 GMT fog had developed and there was light rain the soil saturated. A dull, sunless and the wettest day of the year, so far (Shobdon 12.4C Usk 11.7C , Dalwhinnie -6.4C Capel Curig -0.6C, Ballypatrick Forest 28.4 mm Trawsgoed 21.6 mm, Kirkwall 1.8h Lake Vyrnwy 1.0h) [Max 9.4C Min 1.4C Pptn 21.5 mm]. On the 14th we were still in warm air the temperature at 0900 GMT 7.2C, pressure 1016 mb was rising quickly in a ridge. On the cold side of the frontal system lying over central England it was snowing in Scotland and NE England, From 1130 GMT the temperature began to fall, temperature range today 0.1C Min 7.2C Max 7.3C. At Gorwel Heights the range was, unusually, zero Min 7.3C Max 7.3C (Cardiff 11.9C, Drumnadrochit -1.0C, St Bees Head 31.8 mm, Swyddffynnon 16.8 mm, Thomastown 3.1h St Athan 2.0h Valley 0.5h) [Max 7.3C Min 7.2C Pptn 2.8C]. It was cold overnight on the 15th with an air minimum of -0.2C it was frosty for 0.7h, and a hard ground frost -5.3C. There was a white frost on the fields, concrete was dry, but there was ice on water. A brief red sky earlier turning cloudier at 0900 GMT with weak sunshine. Similar in the afternoon with glimpse of clear sunshine. Pruned the greenhouse vine, best done in January before the sap starts rising. There was moderate to heavy rain after 2200 GMT with rising temperature and falling pressure, the 24-h maximum 8.0C recorded at 0420 GMT (Scilly 10.2C Milford Haven 7.3C, Ravensworth -11.8C Hawarden -2.9C, Strathallan 11.8 mm Whitechurch 1.6 mm, Boulmer 6.1h Bala 2.4h ) [Max 8.0C Min -0.2C Grass -5.3C Pptn 10.4 mm].

The first 15-days were on the cool side with the mean temperature 3.6C (-1.9) & [-1.8] and wetter the 72.7 mm (68%) & [70%] of the new averages. Not as wet as last year 2020 that had 101.3 mm (95%) & [98%] of new averages.

It was a fine and sunny morning on the 16th after a touch of ground frost. After heavy overnight rain the soil was 'soggy'. The temperature at 0900 GMT was 6.2C and with 97% RH visibility was moderate and misty. By 0930 GMT cumulus clouds were developing, but there were sunny spells into the afternoon. Took advantage of the saturated soil to pull out invasive weeds and brambles from the borders, they come out more easily when the soil is soggy (Gosport 11.4C Usk 10.5C, Redesdale -5.4C Lake Vyrnwy -0.9C, Achnagart 38.2 mm Mumbles Head 26.0 mm, Aberdaron 5.3h Valley 4.5h() [Max 8.7C Min 0.4C Pptn 0.4 mm]. There were showers of snow pellets after midnight and the morning of the 17th was bright with weak sunshine. A touch of ground frost, but no white frost seen. Mostly cloudy with just weak sunshine and a few glimpses of clear sunshine in the afternoon (Scilly 9.8C Milford Haven 9.0C, Aboyne -1.4C, Achnagart 15.6 mm Rhyl 2.8 mm, Shoeburyness 5.6h Hawarden 0.3h) [Max 6.6C Min 2.5C Grass -1.7C Pptn tr]. After a dry night the 18th turned out to be very wet. Slight rain had just started at 0900 GMT. Pressure 1021 mb was falling with Atlantic-lows 991 mb to the SW and NW, there was a cold front lying over northern England. Light rain from noon becoming heavy at 2200 GMT (Scilly 11.1C Gogerddan 10.1C, Frittenden -2.2C, Achnagart 15.4 mm Capel Curig 11.2 mm, Leuchars 4.3h Hawarden 0.3h) [Max 9.1C Min 3.1C Grass 0.3C Pptn 31.5 mm] [Gorwel 29.4 mm]. Rain continued moderate to light through the night and by the morning of the 19th it had turned to intermittent drizzle and had accumulated 31.5 mm at 0900 GMT, the largest fall of the month of 18 h duration At Gorwel in Llanfairfechan 29.4 mm had fallen. Pressure 999.8 mb had fallen with complex low 990 mb (Storm Cristoph) W of Ireland. A warm front was lying over N Wales and N England. Today's maximum 10.0C highest of the month. Light to moderate rain most of the day into the night (Charsfield 12.5C Hawarden 11.4C, Aboyne -6.5C, Capel Curig 76.6 mm, Stornoway 4.2h Valley 0.1h) [Max 10.0C Min 5.7C Pptn 21.8 mm] [Gorwel Max 10.6C 28.6 mm]. Another very wet day on the 20th there was a large pool of water on the old cricket field at Gadlys. It does not happen very often, but when it does the soils hereabouts are saturated. It had been windy overnight 30 mph at 0251 GMT. At 0900 GMT 21.8 mm had accumulated over 18h duration. Pressure 982 mb was still falling with a cold front over Anglesey associated with low 978 mb N North Sea. The temperature had fallen from 9.8C to 6.2C. Raining heavily 4 mm was to fall in the next hour, with a burst of 14 mm/h at 0944 GMT. A very dull sunless day with mist visibility was very poor. The River Bollin at Wilmslow, Cheshire had burst its banks. There was snow there in the evening. Heavy snow had fallen during the day on Cairngorm Mountain and turning colder would later fall in Snowdonia (Bude 12.1C St Athan 11.6C, Dalwhinnie -5.9C Mona 5.9C, Capel Curig 87.8 mm, Tiree 2.8h Valley nil) [Max 6.2C Min 6.2C Grass 6.3C Pptn 22.5 mm 19h duration][Gorwel Max 6.6C Min 6.6C Pptn 34.2 mm 18h duration]. On the 21st at 0900 GMT the total rainfall over the past 24-h was 75.8 mm over 55h duration that's 14 mm/h. At Gorwel Heights over the same period 92.2 mm had fallen over 48h duration that's 1.9 mm/h. At Capel Curig in the 72h to 06 GMT 178 mm had fallen with 117 mm at Bala and 110 mm at Lake Vyrnwy (graphic above left). Amber warnings for rain and 200 flood warnings had been issued. On Anglesey large areas of Malltraeth Marsh were flooded. At Lymm near the River Mersey homes were flooded and at Rosset family and their dogs had to be rescued from rising water by helicopter. Another 2000 homes in Dimsbury and Ruthin and Bangor-on-Dee were in danger of flooding. Shops had to shut after a retail park in Rhyl was flooded. Sainsbury's was forced to close its doors after the deluge which has submerged the car park. It did stop raining and during the afternoon the sky began to clear there was a little sunshine, but the temperature dropped from 5.6C at 1537 GMT to 1.3C at 1847 GMT (Manston 9.6C Usk 8.4C, Tulloch Bridge -3.8C, Fyvie Castle 29.4 mm Gogerddan 19.2 mm, Hawarden 6.2h Valley 1.7h) [Max 5.6C Min 1.3C Grass -0.6C Pptn 0.3 mm].

A fine and frosty morning on the 22nd, there was a light white covering on grass made up of ice crystals and frozen dewdrops, the grass jminimum thermometer read -5C, and there was ice on water, the soil was frozen hard. At 0900 GMT the sun had just risen above the mountain cloud on the Carneddau. A little misty with moderate to good visibility, but clear to see the snowline at 2000 ft on the mountains. Pressure 992 mb was rising with low 961 mb S Norway. Polar air in circulation from N Scandinavia brought showers through the North Channel on to the North Wales coastline. Cloudier around noon then some sunshine in t he afternoon. There were ice crystals (h1) floating around in the air about 10 pm. Skewen in South Wales had been badly flooded when after heavy rain there was a 'blow-out' of water from an old mineshaft. Villagers face a seven mile diversion for at least 18 months after Storm Christoph destroyed the 1800s Llanerch Bridge in Denbighshire on the main route between Trefnant and Tremeirchion linking to the A55. Sainsbury's in Rhyl was partially underwater () [Max 5.9C Min 0.7C Grass -5.0C Pptn 0.6 mm]. On the 23rd pressure 996 mb was rising with lows 988 mb off Brest, France, and 974 mb SE Norwegian Sea. It was a bright, cold and frosty morning with a light WNW'ly breeze. Overnight the grass minimum recorded -8.0C and the air temperature at 0815 GMT was -1.6C during 5.7h below zero. The cold plunge from Polar regions continued with shower troughs over the UK. We had a shower of very small graupel (snow pellets) too light in mass to mark the hailpad, but captured landed on the leaves of a dwarf Rhododendron. It was mostly sunshine here in the afternoon with the temperature rising to 5.8C at 1 pm, but there was a snow shower at Gorwel Heights where the temperature struggled to reach 2.9C (Scilly 7.7C Cardiff 6.6C, Spadeadam -0.9C, Braemar -7.7C Sennybridge -5.4C, Rhyl 17.2 mm, Boulmer 7.0h St Athan 5.8h Valley 3.1h) [Max 5.8C Min -1.6C Grass -8.0C Pptn 0.3 mm]. Another cold morning on the 24th with early showers of snow pellets and snow, less than 50% cover at 0900 GMT. Snow was lying at 1000 ft on the mountains, a 30% cover at 500 ft and there was ice precipitation at sea level in places including Rhosneigr. Fine and bright with snow flurries in the afternoon. There was a burst water main on the hill at Gorwel, Llanfairfechan. There another large flaked snow flurry at midnight (Scilly 7.5C Mumbles Head 4.7C, Tn Lake Vyrnwy -1.2C, Dalwhinnie -11.4C Sennybridge -5.3C, Milford Haven 20.8 mm, Boulmer 7.3h St Athan 2.1h Valley 1.5h) [Max 2.9C Min -0.8C Grass -5.5C Pptn 0.7 mm].

Flurries of snow pellets and snow after midnight on the 25th, but it was a very fine and sunny morning though cold. At 0900 GMT the temperature -0.2C (dewpoint -0.6C) after 10.3 h of air frost (minimum -1.9C). There was a covering <50% of snow pellets (grass minimum -7.4C), but little evidence of snow here. Light snow was lying at 500 ft on the Carneddau, with some ice precipitation as low as 250 ft. Little in the way of cloud in the sky but signs of cumuli over the mountains building up a little. Visibility initially poor with some mist, but improving through the morning. The afternoon kept mostly sunny the temperature rising to 6.7C at 1249 GMT (Scilly 8.1C Milford Haven 7.5C, Tx Sennybridge 1.4C, Katesbridge -10.4C Sennybridge -9.7C, Resallach 16.2 mm Scolton 12.6 mm, Shoeburyness 8.1h Valley 6.3h) [Max 6.7C Min -1.9C Grass -7.4C Pptn 1.9 mm]. IThe 26th reverted to poor weather with overcast skies, ragged low cloud and slight rain. Visibility was moderate to good and the slight rain soon ceased. Some remnants of the falls of snow pellets on the grass, The day kept dull and sunless. The number of COVID-19 deaths in the UK sadly had reached 100,000, more than the number casualties that occurred in WWII blitz (Scilly 11.0C Milford haven 9.5C, Dalwhinnie -9.5C Sennybridge -4.2C, Scilly 15.6 mm Mumbles Head 14.8 mm, Lerwick 6.0h Valley nil) [Max 8.4C Min -0.2C Grass -5.1C Pptn 0.6 mm]. The 27th began with thick shallow fog, visibility decreasing to 100 m at 0900 GMT, with the sky obscured. By 10 GMT the fog began lifting slowly, but it was a poor day that was sunless. There was light to moderate ran from 1800 GMT sometimes heavy around midnight when the wind, which had backed and gone around the compass in five hours, strengthened force 5/6 (Scilly 11.3C Whitechurch 10.8C, Baltasound -6.6C Hawarden 2.6C, Millport 9.2 mm Aberdaron 9.2 mm, Lerwick 4.3h Lake Vyrnwy 0.1h) [Max 9.7C Min 3.7C Grass 2.1C Pptn 21.6 mm]. Heavy rain at 02117 GMT fell at up to 11 mm/h and the temperature had been rising and reached 9.5C at 0222 GMT. The air minimum was 7.3C, the highest of the month The barometer bottomed at 998 mb at 0420 GMT on the 28th, as the rain eased towards 06 GMT there was moderate fog and at 0900 GMT it had stopped raining, but visibility was still very poor. Wet overnight with 21.6 mm accumulated over 13 h duration. The wind had moderated and soon the sky cleared a little with weak sunshine putting in an appearance, even a glimpse of clear sunshine. We were in a warm moist SW'ly airflow with pressure on 999 mb rising. A curlew flew over the weather station and there was a buzzard in the vicinity. The usual pheasant was picking around under bird feeders and a red squirrel was at one of the feeding boxes. It was dull again by 11 GMT, but kept dry until 3pm when the fog developed with light rain (Pershore College 14.2C Usk 13.8C Gorwel Heights 12.2C, Braemar -6.8C Valley 0.0C, Killowen 33.2 mm Lake Vyrnwy 30.2 mm, Lerwick 4.1h Bala 0.8h) [Max 9.8C Min 7.3C Pptn 3.5 mm].

On the 29th the sky had been clearing since dawn and it was a fine and bright morning with moderate misty visibility. A pied wagtail put in a brief appearance. The fine start did not last as cloud increased and slight rain and drizzle developed (Gosport 12.1C Cardiff 11.6C, Lerwick -4.6C, Dyce 19.8 mm Capel Curig 14.8 mm, Tiree 6.3h Aberporth 1.9h) [Max 8.6C Min 6.3C Pptn 1.6 mm].

A wintry day on the 30th, it was snowing at 1000 ft at Ogwen and was sleeting here in a strong ENE'ly wind. Light snow was at 500 ft on the mountains and a bit lower by afternoon. There had been a constant roar in the tall trees most of the night, we were somewhat sheltered from it in the garden, but the obs at 0900 GMT was unpleasant. Pressure was on 995 mb with low 974 mb over the Celtic Sea. The afternoon was drier with bits and pieces of sleet and snow on the still strong wind (Culdrose 11.1C Pembrey Sands 8.0C, Tx Balmoral -0.2C Lake Vyrnwy -0.1C, Altnaharra -10.1C Lake Vyrnwy -0.1C, Plymouth 26.8 mm Aberdaron 18.0 mm, Tiree 6.4h Aberdaron 3.9h Valley nil) [Max 3.3C Min 2.4C Pptn 0.6 mm]. There was a red sky briefly after dawn on the 31st, but the sky was overcast at 0900 GMT with moderately high cloud. Pressure on 1002 mb was falling quickly with low 976 mb W of Ireland. Ground frost overnight -4.6C with ice on water. It stayed cloudy all day with some weak sunshine at times no clear sunshine maximum 4.1C at 1515 GMT, and it was dry, the first and only dry day of the month. Windblown snow resulted in the topographic features on the Carneddau Mountains being enhanced in the photos taken today (Scilly 11.4C Valley 4.2C Llansadwrn 4.1C Gorwel Heights 3.4C, Braemar -13.0C Hawarden -3.6C, Culdrose 18.4 mm Whitechurch 6.0 mm, Loch Glascarnoch 6.7h Valley nil ) [Max 4.1C Min 0.3C Grass -4.6C Pptn nil].

The month ended with a total of 180.6 mm of rainfall (169%) & [175%] of the new averages largest since 2008, the 7th wettest in Llansadwrn since 1928. It had been wintry the mean temperature 4.1C lowest since 2010 and the 6th lowest in station records since 1979. It was a dull month, sunshine recorded at RAF Valley was 41.1h (80%) & [73%] of the new averages, lowest since 2019 and 18th lowest on the Anglesey record since 1931, there were 13 sunless days..

February 2021

Wales was under COVID-19 tier four Lockdown...

February 1 - grey skies, cold, but fine and dry, and by 10 am becoming a little brighter. Pressure 997 mb was rising with low 991 mb Scilly in a complex chart. I find the MetO analysis charts more complex and difficult to read these days, no doubt the result of super computers and satellite images. At present the weather is complex forecasters contending with rapidly changing alternating cold polar and warm moist Atlantic airflows. It seems a while since we have had settled weather. I needed a dry spell at the beginning of a month to service the lysimeter. For while the percolate has been coloured, and of late the colour has been stronger. I fill it with the local soil that is slightly acidic, and with 2020 the wettest year on record, and a wet January the soil has had enough and become gleyed. Despite spiking through drainage has become impeded. The aim is to keep the soil moist, but the recent conditions the soil has been waterlogged and under the anaerobic conditions iron compounds in the soil became reduced and leached out. So today was lysimeter service day. The grass top was removed and the under layer of gravel removed and washed. Drainage through the outlet at the base and pipe to the receiver was checked before replacing the washed gravel. I cut out a fresh 30 cm diameter nice piece of turf from the lawn, trimmed the depth to size and placed it in the lysimeter tank. It was ready for use again before the end of the day. You can read about how I constructed and set up the lysimeter back in May 1996 here. (Scilly 11.3C Gorwel 7.0C Porthmadog 6.8C Llansadwrn 6.3C, Altnaharra -10.5C Lake Vyrnwy -1.8C, Camborne 9.4 mm Milford Haven 2.2 mm, Waddington 7.8h Aberdaron 4.8h) [Max 8.7C Min -0.1 Grass -3.0C Pptn 7.3 mm]. An overcast day on the 2nd with low cloud and very poor visibility. Pressure 989 mb had fallen with low 973 mb over Shannon, Ireland. There was an occluded front over the Irish Sea and N Wales. The wind had veered E to SE between 04 and 06 GMT. There was a band of rain across the UK with strong winds to the north Malin Head gusting 54 mph and Bridlington 44 mph. The day was sunless (Cardiff 14.2C, Altnaharra -12.1C, Capel Curig 35.6 mm, Lerwick 4.0h St Athan 0.5h) [Max 10.1C Min 1.7C Pptn 9.8 mm]. The 3rd began brighter after heavy rain at 0145 GMT, the sky to the SE looked lighter, but visibility was poor in mist Pressure 992 mb was rising, the slow-moving low near Shannon 981 mb and the occlusion was over the North Channel. Improving through the morning the afternoon was sunny (Rostherne 11.3C Hawarden 10.5C, Altnaharra -3.9C, Ballypatrick Forest 45.6 mm Capel Curig 16.2 mm, Aberdaron 5.6h Valley 3.4h) [Max 8.6C Min 8.1C Pptn 2.8 mm]. The sky was briefly red to the E early on the 4th, at 0900 GMT the temperature was 7.6C and visibility was just good and a little hazy. There had been a little rain overnight, the morning though mostly cloudy had some weak sunshine. The low of yesterday was now 997 mb over N Ireland. Frontal cloud was to the north of here and the afternoon was sunnier as the sky cleared. Mist and fog central and SE England (Porthmadog 11.4C Gorddinog AWS 11.2C, Altnaharra -3.1C, Logan Botanic Garden 51.0 mm Cardiff 7.6 mm, Aberdaron 7.3h Valley 4.4h) [Max 10.9C Min 6.0C Pptn 2.8]. Not much in the way of cloud on the morning of the 5th with a sunny morning. Pressure was on 1005 mb with the filling slow-moving low 1001 mb near Malin Head. Woodpeckers were drumming in the wood and jets from Valley were in the vicinity flying towards the mountains. Again mist and fog central, E and SE England. The afternoon was disappointing, it had turned cloudy and slight rain developed turning heavier by 1430 GMT (Kew Gardens 11.7C Rhyl 9.5C Gadlys Gardens 8.1C, Shawbury -0.3C, Tyndrum 46.6 mm Porthmadog 8.6 mm, Wattisham 5.8h Valley 2.9h) [Max 8.1C Min 4.3C Pptn 15.0 mm]. Rain overnight heavy just after midnight on the 6th and a dull morning with low cloud and mist. Pressure 1009 mb was rising, but the sky was slow to clear. It was a cooler 3.9C at 0900 GMT and there was an ESE'ly breeze. It was later in the afternoon before there was any sunshine () [Max 5.5C Min 2.7C Pptn tr].

A breezy morning on the 7th with a hint that the sky was clearing, the 2.1C at 0900 GMT felt very cold in the E'ly wind. Pressure was on 1012 mb with a high 1041 mb over the Norwegian Sea and Atlantic-low 992 mb lying to the south-west. This was resulting in a blast of Continental/ Polar air across the UK. It was snowing in SE England at Ramsgate, NE England and E Scotland. Here snow showers across the mountains in the afternoon, snow pellets were reported at Gorwel in Llanfairfechan. Some sunshine then turned dull with ice precipitation 'on the wind' later in the afternoon (Scilly 7.2C Pembrey Sands 5.1C, Braemar -2.7C Whitechurch -1.2C, St Catherine's Point 11.4 mm Scolton 6.4 mm, Stornoway 3.9h Aberdaron 2.5h) [Max 3.4C Min 2.0C Pptn tr]. A fine and bright morning on the 8th after light showers of snow pellets around 08 GMT. With 5 oktas of cumulus clouds there were crepuscular rays wen looking towards the mountains. Visibility was moderate with haze, but broken snow could be seen around 2250 ft with snow patches at 2000 ft with remnants even lower. Expected temperature on the summits today -7C with a wind chill of -18C. There is a huge amount of snow on Cairngorm Mountain ski area this year. Currently blown snow is covering the funicular railway track in places even though it is on stilts (currently not used due to structural issues) and ski runs. It is all closed of course, as is Snowdonia, because of coronavirus lockdown regulations. Some sunny spells in the afternoon, showers from the east off Red Wharf Bay reached here at 1710 GMT with a fall of very small snow pellets or graupel that covered the ground. It was loose and powdery as the surface ground temperature was below zero, it did not melt and remained the same until next day (Scilly 4.5C Milford Haven 4.1C, Fyvie Castle -7.8C Lake Vyrnwy -2.6C, Houghton Hall 4.6 mm Scolton 1.0 mm, Dundrennan 7.6h Hawarden 1.6h) [Max 2.4C Min 0.5C Grass -1.3C Pptn 1.0 mm]. A cold morning on the 9th, but bright with not a lot of cloud. Pressure was on 1010 mb, the jetstream is currently well south of us, usually to the north, it was snowing widely in SE England an elsewhere. The E'ly wind was still with us with a severe wind chill effect on the mountains of about -20C. Here at 0900 GMT -0.5C with a wind chill of about -3C soon penetrating my mittens during obs. The loose powdery snow pellets that fell yesterday evening, plus some more were on the ground, nicely crunchy underfoot. There was some lying at sea level in places as well including Rhosneigr beach. Snow pellets, or other forms of hail on the ground even if covering the ground, do not count as snow (lying) recorded at morning observations. It is very light in weight and when melted the volume is small, it also does not mark the hailometer. A red squirrel was at a nearby feeding box not taking a lot of notice of me doing my rounds of the weather station and garden, too busy eating monkey nuts and hazel nuts. Continuing cold, the maximum 1.7C in the afternoon despite the sunshine. Anglesey (Valley 7.9h) had the most sunshine in the UK today. There was a snow shower between 1335 and 1405 GMT and very large flakes fell at 1455 GMT for a while (Scilly 5.3C _Porthmadog 3.9C, Altnaharra -16.7C Tredegar -3.9C, Charsfield 7.2 mm Tredegar 0.6 mm, Valley 7.9h) [Max 1.7C Min -1.5C Grass -4.5C Pptn tr].

A very fine, sunny and cold morning on the 10th with the ground hard and frozen, there were remnants of icy precipitation in shady places. Very little cloud, just 1 okta, mountains and to the NE over Red Wharf Bay. We still had the easterly wind. Pressure 1019 mb was rising quickly with high 1029 mb, between Iceland and Scotland heading for the Norwegian Sea, with ridge to N France. The North Sea was covered with open cell marine convective clouds heading for the east coast. There was snow on the ground from N Scotland to Kent. There was a good covering of snow on the Snowdonia Mountains with cornices developed on cliffs due to the easterly wind (Scilly 5.0C Usk 4.5C, Altnaharra -17.1C Whitechurch -6.2C, Craibstone 4.4 mm St Athan tr, Kirkwall 7.7h Valley 7.1h) [Max 3.5C Min -2.1C Grass -6.5C Pptn tr]. Cloudier on the morning of the 11th, cold with an overnight minimum of -2.6C in the Stevenson Screen, and -7.3C was recorded by the grass minimum thermometer. The temperature under bare soil at 5 cm depth was 0.3C this rising down the profile reaching 6.3C at 100 cm deep, still above the 5.6C (42F) 'plant growth' temperature. Soil at 50 cm deep was 4.8C too low for growth. Conditions are such that plants in the garden soil are suffering physiological wilt, including my leeks and chard. The freeze drying conditions means that fallen leaf material on the ground in the wood is very dry, as must be leaf litter and surface vegetation on mountains and moorlands not covered in snow. There have been fires on Bodmin Moor in recent days and a large one on Dartmoor today. Fires can move on moors very rapidly in wind, usually the vegetation on wet peat will regrow, but in dry summers when the peat is dry it also can burn and for weeks damaging the ecology (Bridgefoot 5.4C Valley 3.2C, Braemar -23.0C Tredegar -6.5C, Balmoral 4.8 mm Llysdinam 0.2 mm, Leeming 8.9h Hawarden 4.5h) [Max 1.8C Min -2.6C Grass -7.3C Pptn nil]. On the 12th extreme downslope winds off the Carneddau overturned a lorry travelling east on the A55 near Aber, the road was closed with traffic diverted. There were gusts of 46 mph at Gorwel Llanfairfechan and David Lees's Gorddinog AWS station 52 mph just after noon, and 58 mph in the evening. At Gorwel slates were blown from roofs. At the weather station the wind was very turbulent at times bringing down a lot of soot from a chimney. A sunny afternoon. Pressure was still high 1045 mb S Norway and with low 952 mb W of Ireland the easterly continued overnight. A change was on the way with frontal systems stacked up to the SW that would introduce much warmer Atlantic air (Scilly 6.7C Valley 5.4C, Kinbrace -15.4C Lake Vyrnwy -4.8C, Leuchars 7.0 mm Wales nil, Kinloss 7.9h Valley 6.5h) [Max 4.5C Min -0.3C Grass -3.3C Pptn tr]. A dull and cold morning on the 13th with air and ground frost overnight. A brief reddish coloured sky early. The surface of bare soil was dry and frozen, there was a shower of snow grains, small angular translucent hard ice grains that could be heard hitting the ground. Later there was a flurry of small snow flakes. It was windy in Llanfairfechan with gusts of 43 mph at 0112 GMT at Gorwel Heights and 58 mpg at 0847 GMT at Gorddinog off the mountains, here a light ESE'ly (Scilly 10.1C Valley 4.7C, Tx Pennerley -3.1C Lake Vrnwy -2.8C, Tn Loch Glascarnoch -6.5C Tredegar -5.6C, Culdrose 11.4 mm Milford haven 4.0 mm, Wattisham 6.7h Aberporth 0.9h) [Max 9.0C Min -1.7C Grass -5.3C Pptn 2.8 mm]. On the 14th the sky was overcast it was very windy and warmer the temperature at 0900 GMT 8.3C. The SSE'ly wind was blowing force 5/6 and there was a fine drizzle with poor visibility. Pressure 1013 mb was falling rapidly with a frontal wave low 976 mb off SW Ireland. With a Norwegian high 1046 mb isobars were tight over Britain, at Gorddinog a gust of 53 mph at 0900 GMT and at South Uist there was a gust of 70 mph. The temperatures in Llanfairfechan at 0143 GMT was 12.1C. The wind strengthened to strong to gale force in the afternoon with gusts of 61 mph at Valley. Wet in S Wales, sunless day (Armagh 13.3C Capel Curig 11.C, Dalwhinnie -4.9C Lake Vyrnwy -2.8C, Whitechurch 40.4 mm, Thomastown 1.9h) [Max 11.9C Min 0.8C Pptn 2.1 mm]. A fair morning on the 15th, bright and breezy with some weak sunshine at first then breaking through the thin cloud some sunny spells.. There was a mild wedge of air off the Atlantic moving eastward. No overnight frost anywhere it seemed, at 0900 GMT 8.7C this rising to 10.8C by 1332 GMT. The moderate visibility improved a little, just good enough to se that most of the mountain snow had disappeared leaving a few snow patches around 2750 ft and at Don's dyke. Temperatures in Llanfairfechan in the afternoon, Gorwel Heights 12.6C 1530 GMT, then Gorddinog AWS 12.8C at 2330 GMT (Kew Gardens 13.9C Hawarden and Gorwel Heights 12.6C Gadlys Gardens 10.8C, Albemarle 0.1C, Wych Cross 14.4 mm Tredegar 4.8 mm, Wellesbourne 5.0h Valley 2.9h) [Max 10.8C Min 7.8C Grass 5.9C Pptn 2.2 mm].

The first 15-days were wintry with a mean temperature 4.2C (-1.7) & [-1.4] of averages. Precipitation (15.0 mm on the 5th), but some hail and snow at times, totalled 43.5 mm (42%) & [48%] of averages. More sunshine that the whole of January.

The 16th began again mild, but breezy and fairly dull although there were signs of the cloud breaking up and it was sunny at 10 GMT. A heavy shower of rain and ice pellets at 1452 GMT (Myerscough 13.6C Cardiff 12.5C, Cassley 1.2C, Achnagart 31.6 mm Tredegar 21.8 mm, Kinloss 7.9h Aberdaron 4.9h) [Max 10.7C Min 8.2C Grass 6.4C Pptn 8.1 mm]. A fine, but breezy morning on the 17th as a result the 7.4C temperature at 0900 GMT felt quite chilly. Visibiliy was poor in haze at first. Some weak sunshine at first, light showers in the middle of the day then some sunny spells in the afternoon. Sparrows were occupying the penthouse nest site on the house and interest being shown in the terrace nest box, looks like they were nest building. There are about 5 pairs here this year. Increasingly windy in the evening strong to gale force from 2300 GMT as the barometer began to fall rapidly (Pershore College 13.3C Cardiff 11.6C, Fyvie Castle -0.7C, Balmoral 32.8 mm Libanus 24.6 mm, Aberdeen 6.5h Valley 3.9h) [Max 10.3C Min 6.7C Pptn 7.8 mm]. It was a rough night with gusts of 48 mph at 0018 GMT, Gorwel Heights recorded 57 mph at 0315 GMT when the temperature had reached 11.8C, and 58 mph recorded at Valley between 02 and 04 GMT. There was heavy rain just before 05 GMT all down to a cold front passing over between 0500 and 0700 GMT. There was a modest temperature drop of 4C to a minimum of 3.9C recorded on the 18th at 0646 GMT. A breezy morning , with some glimpses of sunshine, the duller afternoon had fewer (Shoeburyness 11.6C Cardiff 10.9C, Banagher Caugh Hill 0.7C, Achnagart 37.4 mm Capel Curig 19.4 mm, St Athan 6.2h) [Max 9.2C Min 3.9C Grass 2.8C Pptn 1.4 mm]. The 19th began with strong to gale force S'ly wind and poor visibility in mist and rain. At 0900 GMT pressure 996 mb was falling with a low to the NW 955 mb covering a very large area of the North Atlantic from Nova Scotia to the Canary islands. There was a warm front lying over the Irish Sea the temperature 9.2C. Capel Curig had had a gust of 71 mph and Gorwel Heights 58 mph. There was a MetO amber warning for rain affecting S Wales and several flood alerts had been issued. Light to moderate rain, the wind moderating in the afternoon, turned moderate to heavy in the evening. Wet in S Wales and the Lake District (Edinburgh Botanic Gardens 13.2C Rhyl 12.7C Gadlys Gardens 11.4C, Westonbirt 1.0C, Keswick 65.4 mm Whitechurch 55.4 mm, Kinloss 1.6h Valley nil) [Max 11.4C Min 4.3C Pptn 18.8 mm 16h duration].

Much the same on the 20th, the morning was very wet and the wind that had moderated was strengthening again. Pressure 993 mb was falling quickly with a frontal-wave low 973 mb Shannon. There was a gale warning in force for the Irish Sea and was so just after noon at Valley gale 8 with gusts of 55 mph, the Scilly Isles had 58 mph. The MetO amber warning was still in force, there was flooding in parts of S Wales. The River Towy burst its banks in Carmarthen and the R. Tywi near Capel Dewi. Roads near Lampeter were underwater and the R. Usk had burst its banks in Crickhowell and Llangattock in Powys. At Llyn-y-Fan, Carmarthenshire 127.6 mm was recorded. Gales in the afternoon with gusts of 42 mph here, 63 mph in Llanfairfechan at Gorwel and Gorddinog (St James Park 15.6C Gorwel Heights 13.8C Gorddinog AWS 13.2C Capel Curig 12.8C, Altnaharra -0.3C, Libanus 70.0 mm, Shoeburyness 6.0h Valley nil) [Max 12.5C Min 9.1C Pptn 5.8 mm]. Much improved on the 21st with a drying S'ly breeze the sky with cirrostratus was clearing to cumulus and for a while lenticular altocumulus. Visibility was good, though a bit hazy. A large number of twigs had been blown off the trees and garden furniture turned over. Fine and sunny, weak at first a few clear sunny spells in the afternoon (Weybourne 15.9C Gorwel Heights 13.1C Rhyl 12.6C, Cassley 2.1C, Achnagart 13.8 mm Pembrey sands 7.4 mm, Kirkwall 6.9h Valley 2.2h) [Max 12.1C Min 12.3C Pptn 0.7 mm]. The 22nd began fine and bright with a light SW'ly breeze. A few cumulus clouds over the mountaintops and a few more could be seen in the far W over the Irish Sea and to the NE towards Cumbria. Pressure was rising and it remained sunny all day. From 18 GMT the S'ly the wind strengthened (Hawarden 13.4C, Tx Dalwhinnie 6.7C Lake Vyrnwy 9.1C, Derrylin Cornahoule -1.3C, Libanus 11.6 mm, Prestwick 8.0h Aberdaron/ Valley 7.6h) [Max 11.1C Min 6.3C Pptn 0.1 mm]. Pressure had started to fall just after midnight on the 23rd and by 0900 GMT it was 1009 mb. The MetO had issued a yellow warning for both wind and rain for North Wales. Wind had strengthened through the night and in the morning was blowing force 8 to 9 in places in North Wales. Capel Curig reported a gust of 76 mph and n Llanfairfechan 64 mph at Gorwel Heights and 61 mph at Gorddinog. The wind was relentless, wind run at Gorwel for the day was 470 miles. The storm (not named!) caused a lot of damage in Llanfairfechan to greenhouses and slates and ridge tiles were removed from the roofs of several properties. It was also very wet, in Llansadwrn 50.6 mm was recorded falling in the 24h to 0900 GMT, rain for 23h duration. There was standing water and a pool on the Gadlys old cricket field and the 19th century haha was filled with water. Power cuts hit three areas of Wales, with an emergency shutdown in Conwy triggered in one place after high winds snapped an electricity pole. Houses in the Dinorwic and Llanberis areas, along with those in Caernarfon and Bangor were without power for a time (Rhyl 15.0C Gorwel Heights 14.3C Gorddinog AWS 14.0C, Kielder Castle -0.6C, Keswick 59.0 mm Capel Curig 36.2 mm, Shoeburyness 8.9h Bala 0.9h) [Max 11.2C Min 6.4C Pptn 50.6 mm]. The 24th was another wet day beginning overcast with very poor visibility in drizzle and mist, but the wind had moderated overnight. Pressure 1014 mb, however, was set to rise with low 972 mb NW of Scotland moving N the warm southern air over the Irish Sea being replaced by something cooler, a high north-east of the Azores seemed likely to extend a ridge towards the UK. Not today, a minor cold front resulted in a temperature fall from 9.8C at midnight to 8.9C at 0900 GMT that was the day's maximum, on to 7.4C at 1930 GMT. There was light rain at first turning moderate for a while in the afternoon, the pool of water standing on the old cricket field remained there all day. Sunless with zero evaporation recorded by M Piche's evaporimeter (Santon Downham 18.4C Hawarden 14.9C, Loch Glascarnoch 4.1C, Capel Curig 49.6 mm, Manston 7.0h) [Max 8.9C Min 8.7C Pptn 9.8 mm].

In complete contrast to yesterday the 25th the sky had cleared and the morning was fine and sunny. The temperature was 6.1C with 97% relative humidity visibility was moderate and misty. The ground was very wet and muddy, but in a light WSW'ly it was drying slowly. Pressure had risen to 1025 mb with the ridge from Azores high 1037 mb extended to Cornwall. Soon a few fair weather cumulus clouds developed, the afternoon was sunny with fine views looking N from near the weather station at Gadlys (Pershore 13.4C Cardiff 13.3C, Fyvie Castle 1.7C, Kinlochewe 10.8 mm Capel Curig 2.4 mm, Aberdaron 9.8h Valley 9.5h) [Max 10.3C Min 5.1C Pptn nil]. The 26th was another fine and sunny day making up for the terrible weather we have been having of late. Pressure 1037 mb was rising in the high centred over the SW Approaches. Low pressure now well N 964 mb SE Greenland and 988 mb North Cape. A little cloud over the mountaintops did start increasing for a while, then diminished, the afternoon mostly sunny (Fyvie Castle 14.4C Cardiff 13.0C, Benson -4.7C Swyddffynnon -2.6C, Lerwick 1.8 mm, Weybourne 9.9h Valley 9.7h) [Max 10.8C Min 3.4C Grass -2.2C Pptn trace dew]. Overnight with clear sky the 'snow moon' was very bright casting a white light on the ground. A cloudier morning on the 27th after a heavy dew and ground frost -1.2C on the grass, but no white frost was seen. Pressure was on 1042 mb over the UK and there was a light S'ly breeze. It was warm enough on the rockery bank with flowering heathers for bees to appear with their familiar humming, a sign of better weather to come. There are white, pink and red flowers in various places in the garden, they find the sunniest patch to feed not minding the colour it seems. Did some work in the sheltered 'hidden garden' today where it was quite warm. The first blue flowers of Chinodoxa 'glory-of-the-snow' are appearing, but sadly there is no snow left on the Snowdonia Mountains that I can see from my lockdown position () [Max 10.6C Min 3.8C Grass -1.2C Pptn trace dew]. The 28th of the month and the last day of climatological winter began calm and without a cloud in the sky. There had been a heavy dew and this had frozen into white frost on the grassy fields around the weather station. Visibility was good, but hazy with Saharan dust in the atmosphere, but none was detected deposited at ground level. Many honey bees were on the heathers flowering on the rockery banks by 0930 GMT, one or two large wild queen bees were also seen. We have a large charm of goldfinches in the garden, more than 10, the BTO says that they are the eighth most common bird recorded in Garden Birdwatch garden list, having increased and moved north in recent years. They keep to lowlands and are not found in mountainous areas. When we first had a garden on Anglesey in the 1960's we were lucky to see one of the first nuthatches, the species northern limit at that time. They too have spread much further north in the last 60 years, they are in this garden too. Spotted the first butterfly of the season in the afternoon, a small tortoiseshell on flowering primroses and other primulas, not seen on the heathers. Insignificant rain UK everywhere (Chivenor 14.0C Trawsgoed 13.6C, Kinbrace -5.8C Capel Curig -3.6C, Tiree 0.4 mm, Aberdaron 10.2h Valley 10.1h) [Max 11.6C Min 2.1C Grass -2.8C Pptn nil].

The month ended with a total of 146.6 mm of rainfall (143%) & [162%] of averages largest since 2019, the 8th wettest in Llansadwrn since 1928. Although wintry at times the mean temperature 6.1C was (+0.2) & [+0.5] of averages, was lowest since 2018 and ranked 16th highest in station records since 1979. It was a sunny month, sunshine recorded at RAF Valley was 92.8h (114%) & [118%] of averages, 20th highest in February on the Anglesey record since 1931, there were 7 sunless days.

Winter was the second wettest on record with 510.6 mm (139%) & [156%] of averages. The mean tempersture 5.4C was (-0.7) & [-0.2] of averages, lowest since 2018.

March 2021

Wales was under COVID-19 tier four Lockdown...

March 1 - a very fine morning without a cloud in the sky, visibility at height was very good, but there was some layered inversion smoke haze along the Menai Straits. Pressure was steady on 1033 mb with out high 1037 mb drifted eastward to be over the North Sea at 0900 GMT, but still covering North Wales. A low 986 mb was over the Atlantic W of Shannon and mist and fog was prevalent in much of central and SE England. No so here, it was sunny all day and we had one of those marvellous aprés sunset skies we get here, peach and azure blue above lasting for about an hour (Porthmadog 14.9C, Shap -4.9C Bala -3.0C, Lerwick 0.8 mm, Aberdaron 10.5h Valley 10.3h) [Max 11.6C Min 3.1C Grass -2.1C Pptn trace dew]. Just a little cloud low in the sky to the E on the 2nd at 0900 GMT. There was a white frost on the grass early with the grass minimum recording -4.3C. A light E'ly breeze, very fine and sunny with bees out on the flowering heathers on the rockery banks. There was no colour in the sky after sunset tonight it looked very grey (Capel Curig 13.3C, Altnaharra -6.6C Capel Curig -4.8C, Scilly 1.4 mm, Morecambe 10.0h Valley 9.5h) [Max 11.6C Min 0.7C Grass -4.3C Pptn nil]. The 3rd seemed a raw damp day when I went out for the obs, very grey with very poor visibility in low cloud. The breeze was NE'ly and I suspect the air was coming off the North Sea so we could call it the haar. The term is used in eastern Scotland and north-east England, its origin is related to Middle Dutch haren. The temperature was 4.3C and the sun was looming through at times was looking white. Pressure was steady on 1028 mb so it was anticyclonic gloom, the jetstream was far north, in fact north of Greenland, Iceland and just on Cap Nord. There was a trough of low pressure 1023 mb over the South West Approaches and most of the UK and Ireland had mist and fog (Camborne 13.5C Bala 10.3C, Dalwhinnie 0.6C, Braemar -7.6C Bala -2.3C, Milford Haven 13.2 mm, Shap 7.6h Aberdaron 2.7h Valley 0.4h) [Max 5.7C Min 1.4C Grass -2.8C Pptn nil]. Another poor day on the 4th and a bit colder 3.7C at 0900 GMT. Little change in pressure with high 1038 mb SE Iceland stretching to the UK. There was a cold front NE Scotland heading southwards. The sun did break through briefly about noon. There was a little rain when the weak cold front passed over between 19 and 20 GMT (Myerscough 10.9C Pembrey Sands 8.3C, Dalwhinnie 2.2C, Shap -2.6C, Bedford 15.4 mm. Tiree 5.8h Valley 0.3h) [Max 5.6C Min 3.1C Rain 0.4 mm]. A much better day on the 5th after a frosty night beginning fine and bright with a few cumulus clouds, but still on the cool side with 3.8C at 0900 GMT. A mostly sunny day the temperature rising to 7.0C just after noon. High 1036 mb was over Scotland and rising here 1034 mb. North Wales had the best of the weather today with the slow moving cold front over the Severn estuary (Porthmadog 8.7C, Lake Vyrnwy 2.9C, Loch Glascarnoch -7.1C Whitechurch -1.7C, Lerwick 2.0 mm, Valley 8.0h) [Max 7.0C Min 1.3C Grass -4.1C Rain nil].

The 6th began brightly after a 'dry frost' well I didn't see any white early on although at 0900 GMT the grass was slightly wet so it could have melted. Measured dew deposition was 0.13 mm and the AWS gauge had tipped recording 0.2 mm. The air temperature had been -0.6C with -6.4C on the grass overnight, there was ice on water too. The temperature now 2.6C rose to 7.3C at 1213 GMT the relative humidity 54% in cold dry air. Pressure was steady on 1037 mb in our own North Wales high. The sky was half cloudy with altocumulus and cumulus clouds and the day fair with sunshine at times, most other places except Cornwall were cloudier today (Gosport 9.4C Trawsgoed 8.5C, Braemar -8.5C Capel Curig -5.8C, Stornoway 5.2 mm, Bude 9.2h Valley 7.9h) [Max 7.3C Min -0.6C Grass -6.4C Pptn nil]. A fine, but dull morning on the 7th feeling cold with a temperature of 3.4C after light air and ground frosts overnight. Dew/ frost deposition was 0.04 mm. Visibility was moderate to good and it was quiet with persistent wood pigeon cooing in the trees. Pressure was still high 1030 over Wales at midnight, the centre had moved to near Gloucester. There was a detached occlusion over Ireland and this was given us the cloudy morning. By 1030 GMT the sky had brightened with sunny spells developing into the afternoon with a maximum temperature of 8.7C at 1539 GMT. Wind strengthened during the evening (Killowen 12.7C Llansadwrn/ Aberdaron 8.7C, Sennybridge -7.7C, Wick 19.0 mm, Camborne 8.1h Valley 5.3h) [Max 8.7C Min -1.0C Grass -6.3C Pptn trace]. Not quite as cold overnight on the 8th being windy and overcast with a little rain around 01 GMT, but a ground frost of -4.2C was recorded by the morning, precipitation on the grass was 0.06 mm with a trace in the rain gauge. Some weak sunshine at 0900 GMT the sky clearing a little. The afternoon was sunny for a while. Traffic on Welsh roads had been 60% higher during the current lockdown. Certainly the traffic past the weather station in afternoon has been more than usual, between 60 and 80 vehicles an hour, up to 100 at times, normally its around 20 to 25 an hour. It is a mystery in the lockdown with only essential journeys allowed and travel for for recreation or taking exercise not allowed, where they have been going. I have not been able to visit any botanical monitoring sites (Murlough 13.2C Usk 12.2C, Lerwick 4.8C Capel Curig 7.1C, Okehampton -5.5C Bala -3.3C, Dunstaffnage 13.6 mm Porthmadog 0.2 mm, Camborne 8.4h Aberporth 7.7h Aberdaron 2.3h) [Max 8.6C Min 1.9C Grass -4.2C Pptn 1.4 mm]. Pressure on the 9th 1019 mb was falling and the dull weather continued with thicker low stratocumulus clouds. The jetstream was strengthening and there was low 994 mb W of Ireland. Our local high pressure system had disappeared, Azores high 1030 mb had a ridge to Brittany and it was sunny in SE England. After a glimpse of bright sunshine around 0830 GMT the cloud had thickened and the rest of the day was sunless. Light to moderate rain with temperature rising from 6.5C in the late evening with the wind strengthening to gale force by midnight (St James Park 14.4C Usk 12.1C, Benson -4.6C Usk -4.4C, Tyndrum 20.6 mm Capel Curig 4.0 mm, East Malling 10.2h St Athan 3.2h) [Max 8.8C Min 5.4C Grass 1.4C Rain 30.0 mm]. On the 10th it was a very wet morning after a rough night, Capel Curig recorded a gust of 86 mph, Aberdaron 84 mph, Valley 58 mph. The jetstream was set up over the UK and there was a low 9599 mb between Iceland and Scotland with another in the wings 968 mb W of Ireland. Pressure here 1005 mb was falling. At 0900 GMT 30.0 mm of rain was measured, there were several large pools of water on the Gadlys 'old cricket field' and water was standing at the weather station. The temperature was 8.8C (RH 98%) and rising, continuous light to moderate rain turned heavy just before noon and very heavy at 1443 GMT was falling up to 16 mm/h, the pools of water on the 'old cricket field' had coalesced into larger pools. Rainfall over 48h to 06 GMT on he 11th at Capel Curig totalled 89 mm, here 53.8 mm and Gorwel Heights 26.2 mm. The maximum temperature 10.6C was at 1830 GMT before a cold front and deepening wave trough crossed here, associated with low 961 mb off W Scotland at 1800 GMT. The roof top anemometer recorded 48 mph when a slate was removed from the roof. Wind run (00-00 GMT) was 410 miles (Hawarden 13.7C, Dalwhinnie 6.0C Tredegar 9.6C, Dalwhinnie 0.4C Tredegar 3.8C, Capel Curig 80.2 mm, Kinloss 4.6h Valley nil ) [Max 10.6C Min 6.5C Rain 23.8 mm].

After the rain and wind storms of the past 48h the 11th dawned fair. The sky was overcast with layered stratiform clouds, but in thinner patches the sun was just visible. Visibility was good albeit hazy. Pressure 990 mb was rising quickly. Deep marine convective clouds were impacted north-west Wales and Scotland during the day. It was still breezy at times, but moderated during the afternoon when between showers of rain, ice pellets and sleet (heaviest 1440 GMT) it was sunny. Fixed a new slate on the roof during one of the better spells. Wind run today was 340 miles (Writtle 13.2C Usk 10.7C, Dalwhinnie 2.1C Lake Vyrnwy 4.6C, Lake Vyrnwy 32.6 mm, Shoeburyness 6.3h Aberdaron 5.2h) [Max 9.0C Min 6.1C Pptn 2.7 mm]. The 12th was a rather dull and cold day, still breezy and the soil was wet and muddy. Pressure 998 mb was still rising with low 960 mb S Norwegian Sea. High 1031 mb was over the Azores and there were shower troughs over the UK. A frontal-wave depression developed W of Shannon at noon and tracked over Shannon by 1800 GMT and proceeded across Anglesey (983 mb at 2300 GMT) reaching Liverpool at midnight. Managed to fit in a lockdown stay-at-home 1 miler round the wood and garden in the afternoon, too cold and muddy to do work in the garden (Teddington 11.7C Usk 10.4C,Dalwhinnie 0.1C Tredegar 1.0C, Lake Vyrnwy 29.4 mm, Kinloss 8.5h Hawarden 4.8h) [Max 8.0C Min 4.0C Pptn 3.4 mm]. It was overcast at first on he 13th the 5.1C at 0900 GMT feeling chilly in the WSW'ly breeze. Pressure 993 mb was rising here, the jetstream was located over the English Channel with low 962 mb S Norwegian Sea and 962 mb 977 mb North Sea. This had an associated cold front over France. It was a blowing a bit in the Channel with gusts of 54 mph recorded at Calais. We were in a flow of Polar open celled convective cloud, there were snow showers over the mountaintops of Snowdonia. The sky started to clear by 10 GMT and the afternoon had some sunny spells. Sycamore leaves on saplings and snowberry in the wood were opening. Gooseberry was also starting to leaf and the sticky buds on horsechestnut looked fit to burst (St James Park 11.3C Cardiff 10.1C, Aboyne -4.1C, Blencathra 28.8 mm Lake Vyrnwy 26.4C. Tiree 8.4h Hawarden 6.4h Valley 4.0h) [Max 7.7C Min 4.4C Pptn 0.4 mm]. A dull day on the 14th, a little rain overnight left concrete and grass wet at 0900 GMT. Visibility was moderate, but the mountaintops were obscured. Pressure 1017 mb was rising with Atlantic-high 1030 mb off Iberia and low 982 mb S Norwegian Sea. Showery rain around noon then wit strengthening wind turning wet with heavy rain just before 18 GMT accumulating 17.2 mm. Rain ceased before midnight (Cardiff 12.5C, Aboyne 0.4C, Capel Curig 27.0 mm, Weybourne 7.5h St Athan 3.8h Valley nil ) [Max 8.4C Min 4.5C Pptn 17.2 mm]. A fine morning in the 15th, though damp underfoot, it was brightening by the minute. Fast trainer jets from RAF Valley were in the vicinity, flying continued on and off through the day. We had two small Texan trainers as well later. A warm feeling day, the temperature rising to 13.3C, I had to take my pullover off working in the garden in the sunny afternoon (Derrylin Cornahoule 14.8C Mumbles Head 13.8C, Drumnadrochit -0.1C, Winchcombe Sudeley Castle 12.6 mm Swyddffynon 5.6 mm, Weybourne 9.6h Bala 6.2h Valley 5.5h) [Max 13.3C Min 5.3C Pptn 3.2 mm].

The first 15-days had temperatures a little below normal the mean temperature 5.9C (-0.9) & [-1.1] of averages. Precipitation totalled 82.5 mm (100%) & [105%] of averages with 53.8 mm falling on the 9th and 10th.

A dull morning under low cloud with mist and rain early on the 16th, but by 0900 GMT there was some improvement, the rain had stopped and visibility was good. Pressure 1029 mb was rising with high 1035 mb Biscay to W of Ireland. Low 1006 mb E Iceland had associated frontal cloud over the Irish Sea. By 10 GMT the cloud was lifting and breaking up. The afternoon was sunny (Pershore 17.9C Cardiff 17.4C, Baltasound -2.8C, Loch Glascarnoch 14.6 mm Gogerddan 8.8 mm, Tiree 10.2h Lake Vyrnwy 6.5h) [Max 13.6C Min 8.0C Pptn nil]. Another cloudy morning on the 17th, but it was bright and fair with very good visibility. Weak sunshine then a sunnier afternoon (Milford Haven 15.4C, Katesbridge -2.3C Trawsgoed -1.7C, Lerwick 2.8 mm, Camborne 7.9h Aberdaron 6.2h) [Max 13.3C Min 3.0C Pptn 0.3 mm]. Fog developed after midnight on the 18th and in the morning with little or no wind visibility was very poor with a fine drizzle. Pressure 1034 mb was high with Omega block high 1040 mb W of Shannon, but not doing us any good with cloud trapped within it thick enough for more drizzle at times through the day (Edinburgh Botanic Gardens 19.0C Usk 16.1C, Yeovilton -2.4C Swyddffynnon -1.6C, Weybourne 4.4 mm, Kinloss 9.9h Bala 4.7h) [Max 10.4C Min 4.5C Pptn 0.6 mm]. Fog at times overnight and on the morning of the 19th it was still misty with good visibility. Pressure was still high 1031 mb the high 1038 mb W of Ireland was edging westwards with the jetstream over the North Sea as far as N Spain. I have used SFSU Meteorology for jetstream charts for 20 years, unfortunately the California Regional Weather Server is no longer being maintained as Prof. David Dempsey passed away last year. It had website functioned automatically till now. A cold front was over East Anglia associated with low 974 mb Svarlbard. Fine, but dull in the afternoon (Tyndrum 17.4C Porthmadog 14.8C, Braemar -2.2C Porthmadog 2.7C, Wainfleet 2.8 mm, Shoeburyness 11.1h Aberporth 2.6) [Max 10.8V Min 6.4C Pptn nil]. Much the same on the 20th with low cloud and mist hanging over the island with moderate visibility. Pressure remaining high was steady on 1034 mb with high 1037 mb W of Shannon. A remnant frontal system over southern Britain kept the S dull and misty while the N was bright with some sunshine. Fine drizzle and spots of rain from 1700 GMT of no measurable volume. Sunless day (Aboyne 17.6C Scolton 12.6C, Aboyne -3.3C, Baltasound 4.0 mm, Charterhall 10.5 Bala 0.9h) [Max 10.3C Min 7.3 Pptn trace]. The 21st began a little brighter with a glimpse of sunshine before 0900 GMT. There had been heavy dew overnight with the grass minimum down to 0.5C. Pressure was on 1032 mb with the high moved to be over the Celtic Sea. There was a remnant weak cold front over Wales, there was a short spell of drizzle at 1330 GMT (unmeasureable amount) and the sun appeared again under the cloud sheet at sunset (Usk 14.2C, Braemar -3.9C Anglesey Mona 4.2C, Lerwick 1.2 mm, Glasgow 11.1h Lake Vyrnwy 9.2h) [Max 9.1C Min 5.4C Grass 0.5C Pptn trace]. After a cool night the morning of the 22nd was fine, but dull. High 1029 mb was stationed over the Celtic Sea and was a little lower 1027 mb here. Visibility was good, no snow was seen on the mountains. The day was sunless, but dry albeit the air seemed a little damp at times in the afternoon (St James Park 15.0C Tredegar 12.3C, Aboyne -5.1C Sennybridge -4.2C, Lerwick 2.0 mm, St Athan 10.8h) [Max 9.6C Min 2.8C Pptn nil]. Much the same on the 23rd except the high pressure had begun to decline and now centred 1029 mb SE Europe. Here pressure 1020 mb was falling slowly with a frontal wave low 988 mb off the Western Isles of Scotland having an associated cold front W of Ireland. It was dull with a cold breeze the SSW'ly picking up. Slight showers of rain in the afternoon with rain coming along later in the evening on the cold front. Blackthorn is now flowering in the hedgerows around Llansadwrn including along the A5025 to Pentraeth and in Beaumaris, unlike hawthorn the conspicuous white flowers appear before the leaves unfold. Flowering 19 days later than last year, but just a day later than the median date over the past 26 years (Hereford 14.0C Cardiff 13.8C, Santon Downham -3.2C, Achnagart 6.6 mm Capel Curig 0.8 mm, Camborne 7.9h St Athan 1.4h) [Max 9.2C Min 6.9C Pptn 3.2 mm]. As the sky cleared after midnight on the 24th it turned a little colder with a touch of ground frost. A fine and breezy morning with a few cirrus and cumulus clouds and good visibility. The day was mostly sunny and the brightest of the month and year so far with solar radiation of 15.14 MJ m ^-2 and brightest 758 W m ^-2 at 1135 GMT; Valley 9.6h sunshine. The highest temperature 11.7C was at 1408 GMT (Usk 15.1C, Kinbrace -1.0C Anglesey Mona 3.0C, Dunstaffnage 19.0 mm Capel Curig 11.4 mm, Valley 9.6h) [Max 11.7C Min 4.8C Pptn 0.6 mm].

A mostly cloudy morning on the 25th after showers of rain overnight, cumulus and lenticular altocumulus clouds. Pressure was steady on 1016 mb with low 979 mb SW Iceland and high 1027 mb over the Pyrenees. The breeze was cold at 0900 GMT, visibility was moderate and there was a little sunshine later. Light showers end of the afternoon (Hull 15.3C Hawarden 14.7C, Bournemouth -1.8C, Capel Curig 20.0 mm, Manston 9.0h Bala 5.6h) [Max 11.1C Min 6.6C Pptn 17.8 mm]. Heavy showery rain after midnight on the 26th with bursts up to 48 mm/h at 05 GMT including wet graupel and 58 mm/h at 0626 GMT that including sleet. Total precipitation recorded at 0900 GMT was 17.8 mm the third largest daily fall of the month. Pressure 1004 mb was rising from 1000 mb at 0616 GMT. A cold front associated with low 973 mb SE Iceland lay across Cape Wrath, Anglesey, Pembrokeshire Islands, Cornwall and Scilly Isles. Scattered clouds with good visibility, snow was seen lying at 2500 ft on the Carneddau Mountains, further wintry showers later in the afternoon (Cavendish 13.9C Usk 11.4C, Lough Fea 0.9C, Achnagart 35.6 mm Sennybridge 14.2 mm, Aberdaron 7.8h Valley 5.7h) [Max 9.4C Min 4.3C Pptn 0.6 mm]. Wintry after midnight on the 27th with some ice precipitation recorded on the hail pad. It was a fine morning with 5 oktas mixed cloud cover and sunny. The strengthening SW'ly wind felt cold the temperature 6.4C. Some further weak sunshine in the afternoon the temperature rising to 10.4C. Warmer in the greenhouse where the Black Hamburg grape had begun to shoot () [Max 10.4C Min 2.3C Pptn 5.8 mm]. It was wet and windy on the 28th, very poor misty visibility at 0900 GMT with moderate rain. There was standing water at the weather station and pools of water had formed again on the old cricket field. There was a cold front over the North channel with low 954 mb SE Greenland. Here pressure 1014 mb was rising after bottoming at 1011 mb at 0326 GMT. A dark sunless day with maximum light level of only 114 W at 1130 GMT. Wind run totalled 450 miles here gusting to 43 mph today compared with 275 miles at Gorwel Heights gusting to 50 mph. Heavy rain up to 20 mm/h fell at 1733 GMT (Normanby Hall 16.2C Hawarden 14.6C, Dalwhinnie 2.3C, Shap 109.4 mm Capel Curig 103.6 mm, Lerwick 6.2h Valley nil) [Max 10.9C Min 6.4C Pptn 13.0 mm]. Another overcast and dull day on the 29th with slight rain and drizzle at 0900 GMT. Visibility was very poor and it was a mild 10.8C with 95% relative humidity. The overnight minimum air temperature was 9.7C the highest of the month. The light level was only 63 W, but it did rise to 132 W in he afternoon. The temperature in Llanfairfechan about 1335 GMT at Gorddinog AWS rose to 15.3C and 15.1C at Gorwel Heights, here it got no higher than the earlier 10.8C (Writtle 20.4C Hawarden 16.0C, Okehampton 6.4C, Achnagart 81.6 mm Capel Curig 21.4 mm, Manston 11.9h Hawarden 10.8h Valley nil) [Max 10.8C Min 9.7C Pptn 0.3 mm]. A quite different day on the 30th beginning almost calm and hardly a cloud in the rather milky looking sky the result of a lot of Saharan dust in the air, but none had been deposited. I was greeted by the first chiffchaff of the season to reach here. Five days later than last year and the median date of arrival on 22-y records, rank 7th latest. Pressure 1028 mb was rising with high 1033 mb S Iceland. Trainer jets from Valley were in the vicinity. Sunny and warm in the afternoon the temperature rising to 18.6C, highest of the month, beating the 17.7C recorded at Gorwel Heights (Kew Gardens 24.5C Gogerddan 21.6C Gadlys Gardens 18.6C, Santon Downham -1.7C, Achnagart 73.4 mm Usk 0.6 mm, Shoeburyness 12.1h Hawarden 9.5h Valley 9.1h ) [Max 18.6C Min 6.2C Pptn nil]. Another fine sunny day on the 31st, a little more cloud in the morning, still the milky sky with hazy sunshine. There was a deposit of yellow/ green pollen from some of the trees with a trace of a darker colour possibly Saharan dust. There was fog on the Irish Sea this affecting coastal areas including Rhosneigr and RAF Valley. Valley was on RED at 10 GMT and there was no flying today. The first bluebells of the season were out in the wood, six days earlier than last year and the median date. The temperature reached 16.8C just after 1300 GMT and solar light of 679 W (Weybourne 23.9C Bala 21.1C, Eskdalemuir -0.2C, Lentran 26.6 mm, Hawarden 9.6h Valley 7.6h) [Max 16.8C Min 9.2C Pptn nil].

Another wet month having a total of 124.7 mm of rainfall (151%) & [159%] of averages largest since 2019, the 11th wettest March in Llansadwrn since 1928. Occasionally wintry at times the mean temperature 7.4C was (+0.5) & [+0.4] of averages, was highest since 2019 and ranked 15th in station records since 1979.

April 2021

April 1 - began brightly and very fine with a light and cool ENE'ly breeze. The sky was very milky again and visibility moderate the result of a lot of Saharan dust in the atmosphere mentioned several times by BBC weather forecasters. Cloud was difficult to see. a mixture of cirrus and cumulus. Little dust was deposited here, my daily sample contained just a trace of dust, it was mostly pollen. Pressure 1025 mb was rising with high 1036 mb S Iceland with a remnant cold front lying across N Wales from N Ireland to The Wash. Sunny afternoon (Bude 17.8C Pembrey Sands 17.3C, Loch Glascarnoch -3.0C Bala 4.9C, Dunkeswell 1.4 mm, Loch Glascarnoch 12.2h Valley 8.8h) [Max 12.1C Min 7.5C Pptn nil].

¤

4.1#

Latest AWS observations Last year's Diary, for previous Diaries consult the site map Snowdonia Snowline for the current season Daily Observations, usually updated bi-monthly Monthly & annual summary with analyses 2021 Temperature graphs, daily and monthly rainfall histograms, accumulated rainfall total and more, all on a page for 2020 The observer's choice of forecasts, satellite imagery, severe weather, natural hazards and more

---

Designed and written by Donald Perkins: Copyright © 1998-2021 Disclaimer llansadwrn-wx.co.uk