Surface station models are the standard method for displaying surface observations on a meteorological chart. Let’s go through each part of the model and explain it in more detail.
Wind is not measured by numerical units. Instead, we use barbs. Small barbs are equal to 5 knots, while large ones are equal to 10 knots. When it gets really windy, we’ll use flags, which are equal to 50 knots. The wind barb points towards the direction the wind is going. The diagram below shows a nice example of some different wind barbs, all of which show a northeasterly (coming from the NE, traveling SW) wind.
Cloud cover is denoted by that circle at the middle. In the example above, it is black, but it is not always black. The chart below is pretty self explanatory. “Sky obscured” means fog.
The pressure observation is the number to the right of the ‘cloud cover’ circle, and it is the last three digits of the observed pressure, with the last digit being to the right of the decimal point. Based on the pressure reading, meteorologists either add a 9 or 10 beforehand to determine the appropriate pressure reading for that station. For example, the pressure above is 1013.8 mb, not 138. However, if the pressure reads something like 999, meteorologists would add a 9 instead of a 10, giving a pressure of 999.9 mb, as that is far more realistic than 1099.9 mb.
Determining whether to add a 9 or a 10 is pretty easy, and although there are situations where there could be an overlap (for example, 400 could correspond to 940 for a tropical cyclone or 1040 for a strong ridge of high pressure), you can just look at nearby stations and other indications on the map to get an idea of what the prefix is.
Temperature and Dew Point:
The temperature and dewpoint are located to the top left and bottom left of the cloud cover circle, respectively. If the station model includes a “current weather” reading, it will divide the two.
These symbols are used to describe the current weather the station is experiencing at the time. The list below shows some of the more commonly-used symbols.
The “current weather” readings are generally only present at airport stations, where the current weather is an optional, additional part of the METARs (Meteorological Terminal Aviation Routine Weather Reports) issued every hour. Most other stations will not have a ‘current weather’ symbol.
Congratulations! You can now read station models. Now, put your knowledge to use!
Written by Charlie Phillips – charlie.weathertogether.net