About Our Weather Station and Website

Our Weather Station

As drone operators the weather is very important to our work. We have been operating a weather station since May 2019, however the current system was installed in January 2022 to replace an all-in-one unit that did not survive its third Shetland winter!

Our weather station is a Davis Vantage PRO2 Plus Integrated Sensor Suite (ISS) that transmits wirelessly to our WeatherLink Live (WLL) unit in our office. The ISS consists of a temperature and humidity sensor in a radiation shield, a 0.2mm "tipping spoon" rain gauge, a solar radiation sensor and a UV sensor. On the pole is an ultrasonic anemometer and wind direction indicator that connects to the ISS. The WLL contains atmospheric pressure, temperature and humidity sesnors.

The ISS transmits observation data to the WLL which is connected by ethernet to our network. These observations are then read by a backend application called WeeWX that runs on a tiny Raspberry Pi computer. WeeWX processes these raw data calculating derived observations such as "feels like" temperature, and quality checking that observations are within a defined range, then archives them in a database. Once archived WeeWX generates various reports for upload to a web server or for further processing. In addition WeeWX sends observation data to various weather sites such as Windy, PWS Weather, the Met Office and Weather Underground. Weather Underground receives observation data every 10 seconds allowing near real-time wind speed and direction.

WeeWX is an open source application that is actively developed (at the time of writing the current version is 4.9). It has an open architecture that allows developers to add extensions to provide additional functionality, and "skins", normally a web interface for the weather data.

Our Davis VP2 Plus Integrated Sensor Suite
Our Davis VP2 Plus Integrated Sensor Suite

Our Website

The front end of our weather station is the website you see here. It is based on the excellent NeoWX Material skin by Neoground GMBH with various enhancements in-house and in collaboration with others on GitHub. Our website is fully responsive and designed for both desktop and mobile / tablet devices, however some pages (e.g. the stats page) display better on a small screen mobile device rotated to landscape format.

Full site on desktop
The Current Conditions page shown full screen on a desktop display

The home page shows cards with the current conditions (refreshed every five minutes) along with min, max and averages for the day. Below the cards is a pressure and wind map with a five day forecast for Lerwick, provided by Windy and the European Centre for Medium Range Weather Forecast (ECMWF). Below that is an animated satellite map provided by Eumetsat via Meteoblue. On the right (or below the satellite map on mobile devices) the interactive charts show observations for the last 24 hours.

Using the menu links you can find observations for yesterday, the current week, the current month and the current year. You will also find reports organised by year then month, a statistics page showing all time highs and lows, and the ephemeris page which displays sun and moon phases, major planets and a sun path diagram to determine the azimuth and zenith of the sun at 60°N (sunpath diagram courtesy of Jaloxa).

Using the Interactive Charts

Interactive charts

The interactive charts allow you to view observations at a specific time, zoom in and out on the observation timeline, zoom in to a selected timespan (click and drag with your mouse to select a region on the timeline), pan along the zoomed timeline, and download the observations in SVG, PNG and CSV formats. Note that on most mobile devices the select zoom and pan options are not available, however you can still zoom in / out and download the images or CSV files.

The CSV download option allows you to download the observation data for further processing in a spreadsheet application (however, please read the copyright, version info and disclaimer link at the bottom of the page for acceptable use). The CSV option is available on all interactive charts: current, yesterday, week, month and year, plus the charts in the reports pages. Charts with multiple observations (e.g. feels like and wind) will include all the data displayed.

Special Observation Cards

Most of the observation cards are self-explanatory, showing current, maximum and minimum values for the time period, however there are four cards that deviate from this: UV Index displays a colour-coded risk indicator from Low, Moderate, High and Very High; Total Solar Radiation displays the cumulative radiation of the period in Wh/m² or KWh/m² plus the min and max values; Wind Run displays the wind run over the last hour, the cumulative total for the day and the maximum 5 minute observation; and on the current conditions page only, Drying Potential. On the Week, Month, Year and Year / Month reports these special observation cards will display averages, totals and highs similar to the standard cards.

Drying Potential is a derived observation that uses a proprietary algorithm to determine how well a damp or wet surface will dry under the current atmospheric conditions. This is a useful indication on how well laundry will dry, as well as roads, paths or anything else that requires air drying.

Special observation cards

The algorithm uses temperature, pressure, humidity, solar radiation, wind and rain observations and trends to display the drying potential on a five point scale: Not Good, Poor, Good, Very Good and Excellent. It also displays the expected trend over the next two to three hours. Although the trend can predict the chance of rain (and improving or deteriorating conditions), the Drying Potential is based on a combination of current conditions and trends over the last three hours and can change every five minutes. It is recommended to use this observation in conjunction with the forecast for the day.