Pressure: Isobars, lines of equal atmospheric pressure, are drawn every 4hPa (hectopascals or millibars). Areas of High and Low pressure are indicated. The closer the spacing of the isobars, the stronger the wind.
Rainfall:Precipitation rate in mm/h averaged over the previous 6 hours. Blue shades show light rain while yellow and red show heavy rain. Precipitation can be rain, hail or snow.
Temperature: Surface temperature predictions over land and sea. Temperatures less than -20°C are shown as white.
Wind: Wind strength in knots (nautical miles per hour) is indicated by the coloured areas. The colours correspond to Beaufort forces (Gale Force, or Beaufort Force 8, is equivalent to 34 knots). Wind direction and strength are indicated by the arrows.
Cloud: Computer generated simulated satellite images. Information displayed is total cloud cover and is similar in appearance to visible satellite imagery.
Wind Flow: Wind flow is represented by streamlines. These follow a path as if carried along with the wind. The colour coding represents the wind strengths associated with the standard Met Eireann warning levels of green, yellow, orange and red. Streamlines are good at showing convergence zones, for example, associated with fronts and lows. The closeness of the streamlines is not directly linked with the wind strength (in a similar manner to isobars); if fact, streamlines can be quite closely packed in regions of even light winds.
Wave: Significant wave height in metres is illustrated by the coloured legend. Mean Wave direction is shown by the arrows (with the length of the tail proportional to the height). Data shown are Total Wave Height which is the sum of Sea (wind driven waves) and Swell (waves from distant storms).
Note: The White shade means No data.
General: The information presented here is derived from Numerical Weather Prediction (NWP) models used in Met Eireann as forecaster guidance. Information for up to 5 days ahead comes from the ECMWF model, presented at 6-hourly intervals. The official forecast may not always reflect the guidance charts illustrated; the forecasters also consider information from satellite, radar and weather observations, in addition to the application of their own experience.
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