Important
Copyright Information
All Information contained within this site unless stated remains
copyright of Chepstow Climate Station. Information supplied is of course
available to view but strictly not to download and utilise in any commercial
form. You may however; electronically copy small portions of data not more than
30 words for your personal use providing you respectfully acknowledge the
source from whence it came, quoting Chepstow Climate Station in the process.
Site
Location, Influences and effects
Chepstow Town borders England and Wales with the River Wye
separating the two countries. In fact as depicted on the map, the borderline
runs through the middle of the river separating the counties of South
Gloucester and Monmouthshire. This is clearly illustrated at the centre of the
old bridge spanning the river at the bottom of the town where incorporated
ironwork shows this. So you could be standing in two countries at the same time
over a river.
The actual sighting of the station is close to the town centre on
a slight incline, which eventually runs down to river Wye basin, generally
typical of most of the town.
The site itself, located in a garden, would probably be classed as
semi-rural if not on the rural side. The most influential constituent effecting
the area and site will be the nearby bodies of water.
This takes form in the River Wye, the Severn Estuary and probably
the Bristol Channel to a degree. These bodies of water tend to keep the air
moist therefore reducing high temperature ranges which otherwise would be
expected over land. This moist air often promotes localised showers, mist and
to a lesser frequency fog.
Summers are generally temperate and not hot, with some occasional
breezes developing when conditions are right. Winters are mild overall, which
can lead to thundershowers or storms during the season. Frosts although common,
are often not severe. Snowfall is not infrequent either, however for it to remain
on the ground is quite rare at present.
Equipment
used for recording
Recording at Chepstow Climate Station began on 25th June 2004 with
basic equipment. With time, more essential precision sensors have been added.
Equipment for recording the climate and weather here is done by
several sensors.
The Lacrosse weather station was installed in June 2005.
The Lacrosse WS3600 monitors outdoor temperatures, dew points,
wind speeds and directions, Precipitation, atmospheric pressure and of course
humidity. The 'Thermo-Hygro' sensor has a shield around it placed 1.25m above
grass in a self-built Stevenson screen as far away from heat reflecting objects
as possible.
There is a self-tipping rain gauge set above ground that records
rainfall and sends it back to the base station. Unfortunately this gauge
recorded at 0.518mm tips so smaller amounts of rainfall below this did not
register until this threshold was reached. It was used an emergency backup and
cross-referencing gauge with about a 94% efficiency recording rate at the
moment. There was a manual observation of rainfall taken at 0900 GMT with a
self made rain gauge positioned 30cm above grass which fed into plastic
container set in the ground. This container was placed below ground to minimise
any evaporation taking place especially during the warmer months of mid spring,
summer and early autumn.
The accompanying anemometer is placed above the roofline of the
house on an aerial pole approximately 9.83m above ground level. This receives
good exposure from nearly all directions apart from the South or Southwest. Due
to a rising incline this affects wind speeds from these directions although
some occasional wind gusts do get through.
This station was decommissioned prior to the new station being
installed. The Stevenson screen not required was taken down and a new painted
post replaced the old one.
A new Davis weather station was installed in December 2009.
This new station records all the necessary parameters not to
dissimilar to the Lacrosse station. There are additional features on the Davis
that the Lacrosse model did not have such as wind speed averages on a daily
basis and over a month, plus rain rates. Intense falls of rain or possibly
thunderstorms are made more accessible through this additional feature proving
useful. The rainfall tip on the Davis of a WMO standard 0.2mm is an improvement
on lacrosse’s 0.51mm tip, proving a little more precise.
The original position of the station was maintained both on the
ground for temperature etc. and in the air for the anemometer. The anemometer
was adjusted for its height and although unknown at present its height should
be read around 9.9 meters or slightly more now.
The 'Instromet' sunshine sensor records daily sunshine amounts. This
sits on the same aerial pole just below the anemometer giving good exposure
during most of the day until later afternoons/evenings depending on time of
year. Unfortunately the sun dips below a hill, with some buildings and a tree
casting a shadow across the sensor especially during winter months when the sun
is at its lowest trajectory.
The very accurate Rosted Digirain the primary precipitation gauge
was installed on 29th December 2005 records precipitation. It is sensitive
enough to record condensation-taking place above ground level.
This gauge is positioned away from any objects that cause 'rain
shadow'.
There is a temperature gauge positioned to record grass/ground
frost as well nearby to the base station.
Sensor sighting on any site is of course tricky but monitoring of
nearby weather stations over time suggests figures are good.
The
Human element
With many automated sensors available today there is plenty of
scope for the human element to contribute a great deal to the recording of
weather and climate here. It is felt that although sensors provide valuable
measured data, they cannot and do not provide the human sensory perception of
actually being at event. For example, the sense of being surrounded by thick
fog, the feel of hail bouncing off your head, the spectacular visual lightning
display during a thunderstorm event all are difficult to replicate by
mechanical means. Granted they can capture these events admirably by camera,
but nothing substitutes being ‘there’ seeing, feeling and witnessing the
happening in the area. So therefore the inclusive reports provided, do have the
human view amid measured data.
Human observations are undertaken daily to be included in monthly
and annual reports.
Oktas (cloud cover) is observed in 80th's along side the current
conditions section observed around 0900 hours GMT every day.
There is an additional section that includes Extreme Weather. This
is a report for any unusual or extreme weather that has affected the site and
immediate surrounding area and is included in the Monthly and Annual Report
section of the website.
Notice
on Site Observations
Please NOTE, that Chepstow Climate Station is an amateur run site
and data and observations provided in reports may not meet the required Met.
Office standard code for a land based Climate Station. However accuracy is
considered important, so the site will endeavour to provide precision in all
parameters. It is hoped over time to provide a fairly accurate climate study
for Chepstow and the immediate surrounding area for the future.
Chepstow
Climate Station Legend
Listed
below are recording parameters and abbreviations used on pages across the site.
Don’t
forget all times are recorded in Greenwich Mean Time (GMT).
When
entering British summertime (BST) between March and October, observations will
require you to take one hour away.
All
Monthly, Annual reports and any other events reported on the site will be
within the GMT time frame listed below in the tables.
Current
Conditions
|
Element |
Abbreviation |
Time Parameter |
General
Information/Requirements |
|
Time |
Time
GMT |
As
shown |
Time of observation in GMT. Times may vary but
kept as close to 0900 as possible |
|
Temperature |
Temp.
C |
At
0900 |
Current temperature in Celsius |
|
Humidity |
Hm
% |
At
0900 |
Current humidity expressed as percentage |
|
Atmospheric
Pressure |
Air
M/bar |
At
0900 |
Current air pressure in millibars |
|
Wind |
Wind
Dir. |
At
0900 |
16-point direction at observation time. Calm
indicates no wind observed or light air |
|
Cloud
cover |
Okta
8ths |
At
0900 |
Expressed in 80s of cloud cover. 9 means
obscured vision, usually with fog |
Daily
Observations
|
Daily
Element |
Abbreviation |
Time Parameter |
General
Information/Requirements |
|
Temperature
Maximum |
Max
temp. |
0900-0900 |
Highest temperature recorded in Celsius, but
figure ‘thrown back’ to the previous day |
|
Temperature
Minimum |
Min
temp. |
0900-0900 |
Lowest temperature recorded in Celsius, but
figure ‘placed forward’ to the next day |
|
Range |
Range
C. |
0900-0900 |
Total span of maximum and minimum temperature
in degrees Celsius |
|
Precipitation |
Mm |
0900-0900 |
Precipitation recorded in millimetres, but
figure thrown back to the previous day |
|
Sun
hours |
Sun
Hrs |
12-12
midnight |
Total hours of bright sunshine recorded |
|
Wind
speed |
Max
speed |
12-12 midnight |
The maximum sustained wind speed recorded in
mph. This is not available on latest reports |
|
Wind
average/ Direction |
|
Monthly |
The average monthly wind speed with the most
dominate wind direction |
|
Wind
gust |
Max
gust |
12-12 midnight |
The highest peak wind gust recorded in mph with
direction |
Extreme Weather
|
Extreme
Elements |
Abbreviation |
Time
Parameter |
General
Information/Requirements |
|
Air
frost |
AF |
12-12
midnight |
Requires the air temperature fall to -0.1c or
below |
|
Grass/Ground
frost |
GF |
12-12
midnight |
Requires the ground temperature fall to -0.1 or
below |
|
Fog |
FG |
12-12
midnight |
Visibility reduced to less than 1000 metres |
|
Mist |
MT |
12-12
midnight |
Visibility reduced but still maintained above
1000 metres |
|
Sleet/Snow
falling |
SF |
12-12
midnight |
Sleet or snow observed falling at site. A
single flake of snow would qualify |
|
Snow
lying |
SL |
At
0900 |
Snow coverage at ground level. Ground must
covered by more than 50% snow cover |
|
Hail |
HL |
12-12
midnight |
All types of hail observed greater than or less
than 5mm |
|
Thunder
heard |
TH |
12-12
midnight |
Thunder heard within audible distance from the
site |
|
Thunderstorms |
|
12-12
midnight |
Total recorded thunderstorms during the month |
|
Gale |
GL |
12-12
midnight |
When wind gusts =>39mph are recorded at the
site |
|
Ice
day |
ID |
0900-0900 |
Requires the temperature to remain below 0.0c
for the 24hrs between 9-9 GMT |
Copyright ©Nick Felstead 2004-2011