Saturday 21st of December 2024
Orange (high pressure)=clear skies, dry, sunny and settled weather, blue (low pressure)=cloudy, wet and unsettled weather. Squashed lines (isobars) = strong winds, spaced out lines = light winds. Wind circulates in an anticlockwise direction around low pressure areas in Europe.
The European pressure maps are provided daily by the United States Department of Commerce scientific agency, The National Oceanic and Atmospheric Administration (NOAA) Physical Sciences Laboratory (PSL) in Boulder, Colorado, United States of America. They are being used here with their permission.
The 500 mb level is usually considered to be the middle of the atmosphere approximately. At this level, the trough and ridge patterns tend to become more evident. Using pressure coordinates shows the height of a pressure level, for example, 500 mb, above the observation stations. The height of a particular pressure level will typically be lower in colder environments and higher in warmer ones. This is because heights increase when the air is warmer and less dense and fall when the air is colder and denser.
[Source: WeatherOps, DTN]
NCEP produces a set of 17 global forecasts each day from nearly identical initial conditions. The differences between the initial conditions are assumed to be within the range of analysis error. The set of 17 forecasts is referred to as the "ensemble forecast". The mean of the ensemble should, on average, have higher accuracy than any individual member.
NCEP (NMC) meaning: National Centers for Environmental Prediction. NMC changed its name to NCEP, the National Centers for Environmental Prediction on October 1, 1995, with the Environmental Modelling Center (EMC) becoming one of its subunits.
[Source: Physical Sciences Laboratory]
Areas of high and low pressure are caused by ascending and descending air. As air warms it ascends, leading to low pressure at the surface. As air cools it descends, leading to high pressure at the surface. In general, low pressure leads to unsettled weather conditions and high pressure leads to settled weather conditions. In summer, high pressure tends to bring fine, warm weather. However, in winter a high pressure system will be associated with cold and dry days and frost. Low pressure in the summer can lead to periods of prolonged rainfall. Low pressure in the winter often signals stormy or wintry conditions. On these charts Orange (high pressure)=clear skies, dry, sunny and settled weather, blue (low pressure)=cloudy, wet and unsettled weather.
[Source: The Met Office national meteorological service, UK]
Learn more about global circulation and the weather in the UK and Europe.
Boulder is located at the base of the foothills of the Rocky Mountains. The city of Boulder is in Boulder Valley, where the Rocky Mountains meet the Great Plains. West of the city are slabs of sedimentary stone tilted up on the foothills, known as the Flatirons. The Flatirons are a widely recognized symbol of Boulder. Colorado is a doubly landlocked state in the western United States encompassing most of the southern Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains. Colorado is bordered by Wyoming to the north, Nebraska to the north east, Kansas to the east, Oklahoma to the south east, New Mexico to the south, Utah to the west, and touches Arizona to the south west at the Four Corners. Colorado is noted for its vivid landscape of mountains, forests, high plains, mesas, canyons, plateaus, rivers and desert lands. Colorado is part of the western and southwestern United States and is one of the Mountain States. Denver is the capital and most populous city of Colorado.
[Source: Wikipedia]
If we are waiting for NOAA PSL map updates, the date labels could become out of sync with the image dates. In that case, the forecast date on the map is the true forecast date. Technical issues at the NOAA PSL computing center could cause this delay and date sync problem. It is also possible that your browser may have stored (cached) old weather maps from a previous day. If this happens, you will have to force the browser to fully reload the web page.
This page is configured to print all 16 weather forecast maps on one page. The pressure maps should be printed in colour as important pressure information is lost if printed in black and white.
All major web browsers support the Ctrl+D shortcut key combination to quickly access the bookmarks creation menu.
These maps provide the best available predictions. Our weather is variable and can at times, especially when predicting further ahead, be unpredictable. Local surface conditions are variable and may differ from these middle atmosphere predictions. We accept no responsibility for any loss or damage caused by following the predictions shown on these maps.
Web page constructed in Newcastle upon Tyne, UK, by Robin Broad , Starbird Digital, June 2020.
Last page update: 7am UTC/ GMT,
Saturday 21st of December 2024
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