Llansadwrn (Anglesey) Weather Observations from the observer's spreadsheet MAY 2009

Graphics

Key to observations.

CLIMATOLOGICAL OBSERVATIONS AT LLANSADWRN, ANGLESEY, FOR MAY 2009
	------09 GMT--->					<-------Air temperature-------->							<---Soil temp--->			<---Earth temp--->			<--State Grd.-->				Rain	Sol	<-------Weather------->						Press	Rain	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	hrs	hrs	evap
1	6	S	6	8	03	10.8	4.4	64	12.9	6.8	9.9	3.6	10.2	10.0	10.9	11.3	11.5	11.1	1	0	1	0	4.1	11.27							1019	2.6	0.0	1.0
2	6	SW	2	7	01	10.7	5.5	70	15.1	5.2	10.2	2.1	10.0	9.3	10.2	11.0	11.5	11.1	1	0	1	0	4.2	22.17							1029	1.8	0.0	2.1
3	6	NW	4	7	02	9.2	6.6	84	13.6	4.7	9.2	2.0	11.0	10.2	11.2	11.6	11.5	11.1	1	2	3	0	2.9	20.83							1029	4.8	0.0	1.3
4	8	SW	5	7	60	8.2	7.1	93	10.8	6.3	8.6	4.2	10.6	10.6	11.2	11.8	11.8	11.2	1	2	3	0	3.6	7.22							1026	4.0	0.0	0.5
5	8	SW	5	7	10	10.8	9.4	91	11.5	7.9	9.7	7.9	11.2	11.2	11.1	11.3	11.5	11.2	1	2	3	0	0.3	7.15							1021	0.3	0.0	1.3
6	8	SW	6	6	21	11.0	10.0	94	13.3	10.0	11.7	9.1	11.0	10.9	11.0	11.4	11.5	11.2	1	1	3	0	4.0	10.60							1016	3.6	0.0	1.6
7	2	SW	5	7	05	10.2	4.7	68	13.0	6.0	9.5	3.9	10.2	9.8	10.8	11.2	11.5	11.2	1	0	3	0	4.5	25.49			4				1012	1.0	0.0	4.0
8	8	SW	7	6	81	9.2	7.5	89	13.2	5.8	9.5	4.8	10.0	10.0	10.8	11.3	11.5	11.1	1	3	3	0	1.2	19.90			4				1002	1.2	0.0	2.2
9	6	SW	5	7	05	9.7	6.0	78	13.1	6.5	9.8	4.0	10.5	10.2	11.0	11.3	11.5	11.2	1	0	3	0	2.6	18.21							1011	3.9	0.0	1.8
10	8	00	0	7	02	10.2	6.6	78	13.2	7.1	10.2	5.0	11.5	11.0	11.2	11.5	11.5	11.2	1	2	3	0	0.0	13.92							1021	0.0	0.0	1.7
11	2	NE	4	7	02	10.2	5.4	72	14.5	7.0	10.8	4.9	11.6	10.2	11.1	11.5	11.6	11.3	1	0	1	0	0.0	29.58							1025	0.0	0.0	3.5
12	2	E	4	7	04	10.5	4.2	65	15.2	4.5	9.9	2.5	11.0	9.8	11.5	12.0	11.9	11.2	0	0	1	0	0.0	29.88							1026	0.0	0.0	3.2
13	6	NE	5	7	04	9.2	5.5	77	12.5	6.3	9.4	4.6	12.3	11.5	12.1	12.5	12.2	11.5	0	0	0	0	9.4	9.64							1018	4.2	0.0	1.1
14	8	NE	2	5	80	12.0	10.3	89	12.4	9.0	10.7	8.5	13.0	12.2	12.0	12.1	12.0	11.5	1	1	3	0	8.6	9.12							1010	10.2	0.0	0.3
15	8	00	0	6	10	10.5	10.1	97	13.7	8.9	11.3	8.8	11.8	11.5	11.8	12.2	12.0	11.4	1	2	3	0	1.1	9.56							1001	1.8	0.0	1.3
16	7	S	5	7	05	11.5	5.2	65	12.5	6.0	9.3	3.4	11.5	11.0	11.6	12.0	12.2	11.6	1	0	3	0	3.3	17.42							995	3.3	0.0	2.8
17	8	SE	3	6	61	9.1	6.3	83	14.6	6.2	10.4	4.2	10.0	10.0	11.2	11.7	11.9	11.8	1	3	3	0	9.8	14.48							1000	9.1	0.0	1.6
18	5	SE	6	7	01	11.6	9.4	87	13.8	6.1	10.0	6.0	12.8	11.9	11.8	11.9	11.9	11.7	1	2	3	0	2.5	21.64							1003	0.4	0.0	2.5
19	6	S	3	7	03	10.4	9.0	91	14.1	8.3	11.2	7.2	10.9	10.8	11.8	12.2	12.2	11.7	1	3	3	0	tr	14.40							1012	0.0	0.0	2.3
20	3	S	4	7	05	13.6	9.3	75	13.7	9.4	11.6	8.3	13.6	12.3	12.2	12.4	12.1	11.8	1	0	1	0	4.8	16.18							1017	4.6	0.0	1.1
21	3	W	3	7	05	11.2	9.6	90	15.3	8.3	11.8	7.8	13.0	12.2	12.4	12.6	12.4	11.7	1	2	3	0	2.6	21.16							1014	2.2	0.0	1.3
22	8	SW	6	7	10	10.5	9.9	96	12.8	8.4	10.6	7.7	12.6	12.4	12.8	13.1	12.5	11.8	1	2	3	0	3.6	8.71							1014	5.5	0.0	0.6
23	6	S	5	7	03	12.8	7.7	71	15.0	10.0	12.5	9.1	14.1	13.2	12.8	12.9	12.9	11.9	1	1	1	0	0.0	14.27							1016	0.0	0.0	1.6
24	2	S	2	8	02	14.8	8.7	67	19.8	5.7	12.8	2.6	13.8	11.7	12.7	12.8	12.9	11.9	1	0	1	0	0.0	27.96							1021	0.0	0.0	2.8
25	3	SW	3	8	02	15.7	8.2	61	19.9	5.7	12.8	3.3	15.1	13.1	13.7	13.7	13.3	12.2	1	0	1	0	3.6	23.61							1017	3.8	0.0	1.7
26	3	W	2	7	01	11.5	7.8	78	15.6	7.2	11.4	5.2	15.2	13.8	14.8	14.9	13.8	12.5	1	1	3	0	4.9	21.22							1015	5.5	0.0	1.8
27	8	S	6	7	10	11.3	10.9	97	16.0	8.7	12.4	6.4	11.9	12.3	13.8	14.2	13.8	12.7	1	2	3	0	tr	11.17							1014	0.0	0.0	0.8
28	6	SW	5	7	01	15.8	13.3	85	19.9	11.0	15.5	10.4	16.6	14.9	14.8	14.4	14.3	12.7	1	0	1	0	0.0	21.15							1029	0.0	0.0	1.5
29	2	S	2	7	01	16.2	13.6	84	21.8	10.6	16.2	6.8	18.0	15.9	15.3	15.2	14.4	12.8	1	0	1	0	0.0	26.59							1032	0.0	0.0	2.9
30	1	SE	2	8	02	19.8	8.8	49	25.3	12.3	18.8	6.7	18.7	16.3	16.5	16.4	14.8	13.0	0	0	1	0	0.0	26.94							1026	0.0	0.0	3.2
31	0	NE	6	8	02	17.4	11.4	68	20.8	10.8	15.8	6.4	19.2	16.6	16.8	16.5	15.4	13.4	0	0	1	0	0.0	27.64							1018	0.0	0.0	3.5
N	66	%
Means---->						11.8	8.1	79	15.1	7.6	11.4	5.7	12.7	11.8	12.4	12.6	12.4	11.7						18.03							1016
Totals----->																							81.6	559.08	0	0	2	0	0	0		71.2	0.0	58.9
MEANS AND AVERAGES AT LLANSADWRN, ANGLESEY FOR MAY 2009
Differences from 1999-2008 average* as used by the Weather Observers Network & from 1971-2000 average**.
Air temperature (C)							*	**		Weather (No. days occurrence)						*		Wind direction (days)								Rainfall (mm)						*	**
	Mean maximum					15.1	-0.6	-0.9			Sleet/ snow falling				0	0.0			N			0					Total				81.4	114	142	%
	Mean minimum					7.6	-0.7	0.6			Snow lying (at 09 GMT)				0	0.0			NE			4					Largest fall				9.8
	Mean (max+min)/2					11.4	-0.6	-0.1			Hail <5 mm				2	0.7			E			1
	Highest maximum					25.3	1.9				Hail >=5 mm				0	{All types}			SE			3				Evaporation (mm)
	Lowest maximum					10.8	0.2				Thunder heard				0	-0.8			S			8					Lysimeter				PE	43.9
	Highest minimum					12.3	-1.3				Gales				0	n.a.			SW			10					Monthly total				PWB	37.7
	Lowest minimum					4.5	0.9				Fog (at 09 GMT)				0	n.a.			W			2									PWS	53.1
	No. days <0.0C					0	0.0			Rainfall (No. days occurrence)									NW			1									PWD	-15.0
Grass minimum mean						5.7	-0.6				Dry		0.0 mm		9	-2.7			Calm			2
Lowest minimum						2.0	1.7				Rain		>= 0.2 mm		20	4.0											Piche (ml)				58.9
	No. days <0.0C					0	-0.7				Wet		>= 1.0 mm		19	7.0			Check days			31
Earth temperature 30cm						12.6	-1.1						>= 5.0 mm		3	-1.8			This month			31

Note: Any peaks seen on the PE graph are due to recent rainfalls 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

.

  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'.

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); Rain hrs hours of rainfall (>0.1mm/hr) 09-09GMT; Fr. hrs hours of frost (09-09GMT).
  Sol MJ/m2 Global Solar Radiation (MJ per m2) 21-21 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; t slight or T heavy thunder heard; G gale; Fog any hour 1, 09 GMT 9.

These pages are designed and written by Donald Perkins © 1998 - 2009 http://www.llansadwrn-wx.co.uk