They are used to show many weather observations on a map.
Show observations are at the surface.
Can show the spatial relationship of weather observations.
Temperature (shown in red here) and Dewpoint Temperature (shown in green here) are reported in °F to the nearest whole number.
In this example:
Temperature = 56°F
Dewpoint temp = 50°F
Wind barbs (plotted in magenta here) represent the wind direction (in degrees) and the wind speed (in knots).
In this example, the wind is coming from the north (0 degrees) at 15 knots.
If there is a wind gust reported, it will be written on top.
In this example, the wind is from the north at 15 knots gusting to 27 knots.
If the winds are calm, they are indicated by a circle around the central point.
In this example, the wind would be reported as calm.
The center circle represents cloud cover.
Image Description: Cloud Cover Indicators
The following indicators refer to the center circle of a surface station model.
Open, not filled : Clear Conditions
Open, not filled: Sky clear
A line down the middle : Few Clouds (12.5% - 25%)
1/4 filled : Scattered Clouds (37.5 - 50%)
3/4 filled : Broken Clouds (62.5% - 87.5%)
Filled in : Overcast (100%)
"X" : Sky is Obscured
"M" : Sky Cover is Missing
In this example, the cloud cover is overcast.
Visibility is reported in statute miles (shown in light blue here).
In this example, the visibility is 3/4 statute miles.
Significant Weather is reported by special symbols (shown in yellow here).
In this example, the significant weather is light rain.
Sea-level pressure (SLP) is reported in the top right (shown in pink here), and is done in the same manner as a METAR:
A decimal goes between the second and third numbers.
If the first two numbers are:
> 50, add a 9 on the front
< 50, add a 10 on the front
In this example, the sea level pressure is 1010.7 mb.
Pressure Tendency is reported in the bottom right (shown in purple here).
It is defined as the 3-hour pressure change, in tenths of a mb.
The symbol illustrates how this pressure change occurred over the past 3-hours.
In this example, pressure continuously fell 1.5 mb in the past 3 hours.
Temperature: 20 °F
Dew Point: 16 °F
Wind: 5 kts from the north
Cloud Cover: Sky Cover Missing
Visibility: 8 Statute Miles
Current Weather: Thick Fog
Sea-level Pressure: 980.7 mb
Pressure Tendency: Increasing 2.8 mb continuously