Davis Vantage Vue AWS at Gorwel Heights in Llanfairfechan.

Llansadwrn (Anglesey) Weather:
Monthly and Annual
Summary for 2020

Logo: Llansadwrn Weather - Melin Llynnon, Ynys Môn




January 2020

Wet, windy, mild and dull: Rainfall and temperatures well above averages, rather dull

The beginning was very mild, wet and windy, The end was more wintry and unusually foggy at times

Rainfall totalled 154.2 mm (158%) & [151%] of averages, largest since 2016 and ranked the 13th wettest Decembers in Llansadwrn since 1928. The wettest day and raining for 18 hours was on the 11th having 32.5 mm, other wet days were the 8th with 16.0 mm and the 16th with 24.2 mm. Despite the wet days there were 3 (-1.0) that had no precipitation, dry days (having <0.2 mm) numbered 7 (-1.6). Rain days (>=0.2 mm) were 24 (1.6); wet days (>=1.0 mm) were 16 (-0.9); and days that had 5 mm, or more, 10 (3.0). Rainfall duration (wet hours) was 138 and the average rainfall per hour was 1.1 mm.

Rainfall at Gorwel Heights was 126.0 mm [111%] with the wettest day on the 11th with 30.2 mm. There were 11 dry days; 20 rain days; 14 wet days and 7 had 5 mm, or more. Wet hours were 98 less than Llansadwrn, but the average rate of fall was 1.3 mm/h was greater.

Temperatures were well above averages. The mean temperature at Llansadwrn was 6.4C (1.1) & [1.3] of averages, highest since 2016. The mean maximum 8.7C (1.0) & [1.1] was highest since 2016 and ranked 6th in station records since 1979. The highest maximum was 11.6C on the 7th (-0.2) closely followed by the 11.5C recorded on the 7th. The lowest maximum was 5.5C on the 9th. The mean minimum was 4.0C (1.2) & [1.4] highest since 2008 ranked 8th. The lowest minimum on the 18th was -0.2C (1.8) the only day with air frost, but that lasted for only 0.5h. There were, however, 14 (-4.0) days with ground frost equal lowest with 2016/17 since 2008, the lowest -4.5C (2.2) on the 18th. The warmth was reflected also in the soil temperatures: the mean at 30 cm 6.4C (1.0) and at 100 cm 7.9C (0.6).

Temperatures at Gorwel Heights in the Llanfairfechan microclimate were remarkable for January. The mean 7.6C 1.2 degrees higher than Llansadwrn had an anomaly of [1.4] based on 1981-2010 Met Office Llanfairfechan DataPoint. The mean maximum was 10.0C with 16 days in the month of 10C, or more. A record Föhn-enhanced maximum of 16.9C at Gorddinog and 17.4C was recorded in Llanfairfechan at 1250 GMT on the 7th at Gorwel Heights both stations beating the previous highest 15.0C recorded on this date at Rhyl in 1934 and at St. Abbs Head in 1989 (TORRO). The lowest maximum was 5.5C on the 28th. The mean minimum at Gorwel Heights was 5.2C, the highest 8.5C on the 31st and the, lowest 1.8C on the 28th there being no air frost recorded.

The wind direction was predominately SW'ly 15 days in Llansadwrn and 18 days at Gorwel Heights. No snow was seen in Llansadwrn, but there were 6 days when small hail (snow pellets and ice pellets) were recorded. Sunshine at RAF Valley was 48.0h (90%) & [83%] ranked 32nd lowest on the Anglesey record since 1931. The sunniest days was on the 16th and 20th with 6.1h. There were 15 sunless days

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Monthly data 2020

Llansadwrn (Anglesey): Monthly weather data summary for 2020
Anomaly ~ is based on the 2010-19 average.
Anomaly 30-y is based on the 1981-2010 average.
.
.
Air temperatures (C) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
.
Mean max 8.7 8.7
Mean min 4.0 4.0
Mean 6.4 6.4
Anomaly~ 1.1 0.2
Anomaly 30-y 1.3 0.4
High max 11.6 11.6
Date 16 .
Low max 5.5 5.5
Date 9 .
High min 7.0 7.0
Date 6 .
Low min -0.2 -0.2
Date 18 .
Grass min -4.5 -4.5
Date 18 .
.
MSL Pressure at 09 GMT (mb) 1017 1017
Highest 1049 1049
Date 20 .
Lowest 978.7 978.7
Date 14 .
.
Means at 0900 GMT .
Air temperature (C) 6.1 6.1
Dew point (C) 4.5 4.5
RH% 90 90
Soil temperatures (C) .
.
5 cm 5.4 5.4
10 cm 5.7 5.7
20 cm 5.8 5.8
30 cm 6.4 6.4
Anomaly~ 1.0 -4.8
50 cm 7.0 7.0
100 cm 7.9 7.9
Anomaly~ 0.6 -3.6
.
Rainfall (mm) .
.
Rain tot 154.2 154.2
Rain % ave~ 158 13
Rain % 30-y 151 14
Days 0.0 3 3
Days <0.2 7 7
Days >=0.2 24 24
Days >=1.0 16 16
Days >=5.0 10 10
Max fall 32.5 32.5
Date 11 .
Highest rate (mm/h) 70 70
Date 16 .
Average rain per hour (mm) 1.1 1.1
.
Evaporation .
.
Piche (mls/ mm) 27.7 27.7
Lysimeter PE (mm) 32.6 32.6
AWS ET calculated 18.6 18.6
.
Weather (days) .
.
Air frost 1 1
Ground fr 14 14
Sl/snow 0 0
Sn lying 0 0
Thunder 0 0
Hail <5 mm 6 6
Hail >=5 mm 0 0
Fog at 09h 2 2
Gales in SE Anglesey 5 5
.
Wind direction at 09h (days) .
.
N 0 0
NE 0 0
E 1 1
SE 2 2
S 5 5
SW 15 15
W 6 6
NW 0 0
Calm 2 2
.
Wind speed mph .
.
Daily mean 8.8 8.8
Highest daily mean 18.3 18.3
Date 7 .
Mean gust 26.0 26.0
Highest gust 53 53
Date 13 .
.
AWS records of rainfall and frost .
.
Wet hours (with 0.2 mm,or more) 138 138
Frost duration (h) 0.5 0.5
.
Cloud cover at 09h. Mean % 75 75
.
Global solar radiation (MJ m-2) .
.
Llansadwrn
Sol rad mean 2.38 2.38
Maximum 4.80 4.80
Date 20 .
Minimum 0.53 0.53
Date 11 .
Brightest hour W/sq m 271 271
during hour beginning GMT 12 12
on day 20 .
Sunless days 14 14
.
Sunshine (h) .
.
Valley 48.0 48.0
Average %~ 90 0 0 0 0 0 0 0 0 0 0 0 3
Average 30-y 83 0 0 0 0 0 0 0 0 0 0 0 3
Sunniest 6.1 6.1
Date 20 .
Sunless days 15 15
.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year

Llanfairfechan, Gorwel Heights observations

Gorwel Heights (73 m), Llanfairfechan (Conwy): Monthly weather data summary 2020
# Anomalies based on 1981-2010 MetO Llanfairfechan DataPoint
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Air temperatures (C)
.
Mean max 10.0 10.0
Mean min 5.2 5.2
Mean 7.6 7.6
Anomaly [1981-2010] # 1.4 -3.1
.
High max 17.4 17.4
Date 7 .
Low max 5.5 5.5
Date 28 .
High min 8.5 8.5
Date 31 .
Low min 1.8 1.8
Date 28 .
.
MSL Pressure at 09 GMT (mb) 1016.6 1017
.
Highest 1048.9 1049
Date 20 .
Lowest 978.4 978
Date 14 .
.
Means at 0900 GMT
Air temperature (C) 7.3 5.8
Dew point (C) 4.3 42.7
RH% 81.0 81
.
Rainfall (mm)
.
Total 126.0 126.0
% [1981-2010] # 111 11
.
Max fall 30.2 30.2
Date 11 .
Highest rate (mm/h) 53 53
Date 13 .
.
Wet hours (with 0.2 mm, or more) 98 98
Average rain per hour (mm) 1.3 1.3
.
Days <0.2 11 11
Rain >=0.2 20 20
Wet >=1.0 14 14
Days >=5.0 7 7
.
Weather (days) .
.
Air frost 0 0
Frost duration (h) 0 0
Wind direction at 09h (days) .
.
N 1 1
NE 0 0
E 0 0
SE 2 2
S 6 6
SW 18 18
W 1 1
NW 1 1
Calm 2 2
.
Mean mph 6 6.0
Highest daily mean mph 16.3 16.3
Date 11 .
Mean gust 27.6 27.6
Highest gust 59 59
Date 13 .
.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year

Acknowledgements

The Met Office at RAF Valley kindly supplied observational data from 1942 to 2011. Current data (provisional) are gathered from SYNOP reports and METAR, any missing observations are initially derived from nearby stations to complete the record, up to date figures are later gathered from the Met Office website. I am grateful Ivor McLean former Met Officer at RAF Valley for early Holyhead sunshine and various other observations; David Lee for use of his observations from Gorddinog; and Gordon Perkins (BlueTractorSoftware) for observations at Gorwel Heights and help with additional observations.



Designed and written by Donald Perkins © 2020

Page first dated 3 February 2020

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