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Llansadwrn (Anglesey) Weather

Observations from the observer's spreadsheet

SEPTEMBER 2020

 Logo: Llansadwrn Weather - Melin Llynnon, Ynys Môn.

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CLIMATOLOGICAL OBSERVATIONS AT LLANSADWRN, ANGLESEY, FOR SEPTEMBER 2020
------09 GMT---> <-------Air temperature--------> <---Soil temp---> <---Earth temp---> <--State Grd.--> Rain Sol <-------Weather-------> Press Pptn Fr. Pch
DD N dd ff V ww Temp Dpt RH Max Min Mean Gmin 5cm 10cm 20cm 30cm 50cm 100cm E C Gr SS mm MJ/m2 S L H T G F mb W hrs hrs evap
1 1 S 2 8 03 15.1 11.1 77 18.7 8.3 13.5 4.9 14.2 13.7 14.8 15.3 16.0 15.8 1 0 1 0 1.2 11.73 1021 1 0.0 2.7
2 8 S 5 6 61 13.6 12.5 93 16.9 12.8 14.9 9.0 14.5 14.8 15.2 15.8 16.0 16.0 1 3 3 0 15.2 4.15 1015 11 0.0 0.7
3 7 SW 5 5 80 15.3 14.3 94 17.8 13.4 15.6 11.4 16.1 15.8 15.6 15.8 15.8 15.9 1 3 3 0 tr 9.66 1012 0 0.0 1.1
4 7 SW 4 6 06 14.3 11.4 83 15.8 10.6 13.2 5.6 15 14.5 15.2 15.8 16.1 15.8 1 0 1 0 2.7 11.16 1020 4 0.0 1.1
5 6 W 3 6 03 13.1 11.3 89 16.1 9.6 12.9 5.5 14.9 14.0 15.0 15.6 15.8 15.8 1 2 3 0 1.1 10.00 1022 4 0.0 1.0
6 7 W 2 5 80 14.1 13.3 95 18.5 9.8 14.2 5.5 15.6 15.1 15.5 15.7 15.8 15.8 1 3 3 0 0.9 10.36 1020 2 0.0 1.0
7 8 SW 5 6 58 14.1 12.9 93 16.8 11.4 14.1 7.1 14.9 14.9 15.6 15.8 16.0 15.8 1 3 3 0 1.8 5.34 1020 4 0.0 0.6
8 8 SW 4 7 02 16.8 15.9 94 20.4 13.6 17.0 12.3 16.8 16.3 15.8 16.1 16.0 15.4 1 2 3 0 4.9 9.75 1023 5 0.0 1.0
9 3 NW 3 7 03 13.4 12.8 96 17.7 11.1 14.4 7.4 16.0 15.7 16.2 16.3 16.0 15.6 1 2 3 0 0.1 10.46 1025 1 0.0 0.8
10 7 SE 2 7 05 13.1 10.8 86 16.1 10.1 13.1 5.8 15.2 15.0 16.0 16.2 16.2 15.5 1 1 1 0 0.0 8.31 1025 0 0.0 2.4
11 8 SW 5 6 03 14.2 12.2 88 16.3 11.6 14.0 8.8 14.0 14.4 15.5 15.9 16.0 15.6 1 0 0 0 3.4 7.80 1013 5 0.0 1.2
12 5 SW 3 6 05 13.7 12.1 90 16.6 10.9 13.8 6.7 13.7 13.7 15.0 15.6 15.8 15.6 1 2 3 0 0.0 14.02 1017 0 0.0 2.8
13 8 SW 6 7 05 15.5 14.4 93 18.1 13.6 15.9 11.6 15.3 15.3 15.5 15.8 15.8 15.6 1 0 0 0 tr 8.42 1019 0 0.0 1.6
14 4 S 2 8 06 16.3 14.6 90 24.8 11.8 18.3 7.2 14.9 14.5 15.2 15.6 15.8 15.6 1 2 2 0 tr 13.47 1 1021 1 0.0 1.8
15 5 00 0 8 06 19.7 16.1 80 24.7 16.3 20.5 12.4 17.2 16.7 16.5 16.5 16.3 15.5 1 0 1 0 0.1 11.38 2 1018 1 0.0 1.4
16   NE 2 2 45 15.2 14.7 97 19.4 12.1 15.8 8.5 16.4 16.3 16.6 16.8 16.5 15.5 1 2 2 0 0.0 12.44 9 1026 0 0.0 1.3
17 6 NE 2 6 04 15.3 13.5 89 23.2 11.5 17.4 6.9 15.7 15.3 16.5 16.7 16.7 15.9 1 1 1 0 0.0 13.74 1030 0 0.0 1.7
18 6 NE 4 8 05 12.4 9.8 84 17.1 9.8 13.5 3.4 13.8 14.4 16.0 16.7 16.7 15.8 1 0 1 0 0.0 13.56 1026 0 0.0 2.4
19 5 NE 5 7 06 13.4 10.6 83 17.6 10.7 14.2 6.0 13.3 13.6 15.2 16.0 16.2 15.8 0 0 1 0 0.0 13.77 1022 0 0.0 2.2
20 0 NE 4 8 06 12.8 10.0 83 18.6 10.9 14.8 7.1 13.0 13.3 15.0 15.6 16.0 15.9 0 0 1 0 0.0 13.93 1022 0 0.0 1.2
21 6 SW 2 6 10 14.6 13.9 96 21.2 10.6 15.9 7.2 14.8 14.2 15.0 15.3 15.8 15.8 0 0 2 0 0.0 13.98 1 1019 0 0.0 1.6
22 8 S 5 6 10 14.1 13.3 95 15.2 11.3 13.3 8.6 14.5 14.8 15.2 15.6 15.8 15.8 0 1 1 0 22.2 2.28 1008 10 0.0 0.6
23 6 N 3 7 01 11.1 10.1 94 14.5 9.9 12.2 8.9 13.4 13.8 14.9 15.2 15.6 15.6 1 2 3 0 3.4 9.85 1001 7 0.0 0.9
24 6 SW 3 6 25 9.7 8.5 92 11.3 6.3 8.8 2.9 11.6 12.3 14.0 14.8 15.4 15.6 1 2 4 0 3.3 6.30 4 990 4 0.0 1.7
25 3 N 5 8 03 11.3 7.6 78 13.7 6.7 10.2 3.8 10.6 11.2 13.2 14.0 15.0 15.2 1 1 3 0 0.2 8.87 4 1010 1 0.0 2.2
26 6 NE 5 8 01 9.9 6.2 78 13.4 7.4 10.4 4.6 10.1 10.7 12.8 13.7 14.8 15.0 1 0 0 0 0.0 11.19 1017 0 0.0 2.0
27 5 NE 2 7 05 10.4 8.0 85 14.8 6.3 10.6 2.3 10.7 10.9 12.8 13.5 14.4 15.0 1 0 1 0 0.0 11.97 1018 0 0.0 1.0
28 8 S 2 8 02 13.8 12.6 92 16.8 6.3 11.6 2.4 12.1 11.8 12.8 13.4 14.2 14.9 1 0 1 0 2.6 4.78 1013 4 0.0 0.4
29 1 S 2 7 10 10.4 10.1 98 16.4 7.9 12.2 3.8 10.3 11.1 12.8 13.3 14.0 14.7 1 2 2 0 1.4 8.31 1018 3 0.0 2.0
30 8 S 6 6 80 13.3 11.8 91 15.1 10.1 12.6 7.4 12.6 12.7 13.1 13.8 14.2 14.5 1 3 3 0 7.0 4.93 1 1000 11 0.0 0.6
N 72 %
Means----> 13.7 11.9 89 17.5 10.4 13.9 6.8 14.0 14.0 15.0 15.4 15.7 15.5 9.86 1017
Totals-----> 71.5 295.90 0 0 2 0 1 4 79.0 0.0 43.0
MEANS AND AVERAGES AT LLANSADWRN, ANGLESEY FOR SEPTEMBER 2020
Differences from 2010-2019 average* as used by the Weather Observers Network & from 1981-2010 average**.
Air temperature (C) * ** Weather (No. days occurrence) * Wind direction (days) Rainfall (mm) * **
Mean maximum 17.5 0.7 0.2 Sleet/ snow falling 0 0.0 N 2 Total 71.5 65 75 %
Mean minimum 10.4 -0.4 0.1 Snow lying (at 09 GMT) 0 0.0 NE 7 Largest fall 22.2
Mean (max+min)/2 13.9 0.2 0.1 Hail <5 mm 1 1.1 E 0
Highest maximum 24.8 2.5 Hail >=5 mm 0 {All types} SE 1 Evaporation (mm)
Lowest maximum 11.3 -0.9 Thunder heard 0 -0.2 S 7 Lysimeter PE 52.8
Highest minimum 16.3 0.9 Gales 1 n.a. SW 9 Monthly total PWB 18.7
Lowest minimum 6.3 -0.6 Fog (at 09 GMT) 1 n.a. W 2 PWS 40.2
No. days <0.0C 0 0.0 Rainfall (No. days occurrence) NW 1 PWD -21.5
Grass minimum mean 6.8 -1.2 No pptn 0.0 mm 10 1.5 Calm 1 AWS ET 44.6
Lowest minimum 2.3 -0.1 Dry < 0.2 mm 15 6.5 Piche P I 43.0
No. days <0.0C 0 0.0 Rain >= 0.2 mm 15 -3.3 Check days 30
Earth temperature 30cm 15.4 0.1 Wet >= 1.0 mm 13 -0.2 This month 30
>= 5.0 mm 3 -3.8

Sep_temp.gif Sep_rain.gif Sep_msl.gif Sep_soil.gif Sep_sol.gif Sep_rh.gif Sep_wind.gif Sep_pe.gif

Note: Unusual peaks seen on the PE graph are due to recent rainfalls or unmelted snow having not yet percolated through the soil. This method is not good for daily measurements, but good results are obtained over 3 days (allowing time for percolation) and on a monthly basis. The lysimeter also measures dew and depositions of frost, and is a better raingauge than one with a rim at 30 cm high. In winter, when evaporation from the ground is low, negative values are sometimes seen and indicate an accumulation of dew and frost, and more rain than measured by a standard raingauge. In summer, when evaporation is high and rainfall less, the lysimeter still measures dew and more rain than the standard gauge, but the effect is less noticeable. The daily graph is show here for it's interest and you can read more about this 'classic' method of measuring evaporation here

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KEY: OBSERVATIONS AT 09 GMT

  DD date; N cloud (oktas, 9=obscured); DD wind direction (8 sectors, 00=calm); ff wind speed (Beaufort scale);
  V visibility (0 dense fog, 1 thick fog, 2 fog, 3 moderate fog, 4 very poor, 5 poor, 6 moderate, 7 good, 8 very good);
  WW present weather SYNOP code (eg. 01 cloud decreasing, 02 sky not changing, 03 cloud increasing, 04 smoke haze, 05 haze)
  Temperatures (degC); Temp dry bulb temperature; Dpt dewpoint; RH relative humidity (%); soil temperatures are under bare
  soil and earth under grass; SS snow depth (cm); Press air pressure, aneroid (mb). For state of the ground E, concrete C,
  and grass Gr codes consult the page on 'Recording Atmospheric Depositions on Grass'. =0 bare soil very dry and cracked.
 

24 hour observations...

  Max maximum temperature (degC) beginning 09GMT; Min minimum temperature ending 09GMT;
  Gmin grass minimum temperature (degC) ending 09GMT; Pch Evap Piche evaporation (ml) beginning 09GMT;
  Rain rainfall beginning 09GMT (mm); Pptn  W hrs number of hours with precipitation 09-09GMT; trace <0.05 mm; tr trace of rain; tr dw trace of dew;
  tr fr trace of frost; Fr. hrs hours of frost (09-09GMT).
  Sol MJ/m2 Global Solar Radiation (MJ per m2) 00-00 GMT. 

Monthly observations...

  PE Potential evapotranspiration, PWB Potential water balance, PWS Potential water surplus, PWD Potential water deficit.

Weather: days with...

  s slight or S heavy snow/sleet falling; L >=50% snow cover at 09GMT; H categories of hail: 1 ice crystals, 2 snow grains,
  3 snow pellets, 4 ice pellets, 5 hail 5-9 mm, 6 hail 10-19 mm; up unidentified precipitation;
  t slight or T heavy thunder heard; G gale; Fog any hour 1, 09 GMT 9. Gales (Beaufort land scale) refer to the area.

These pages are designed and written by Donald Perkins © 2020 llansadwrn-wx.info

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