1. Reading Weather Maps

2. How to Read Surface Weather Maps On surface weather maps you will often see station weather plots. On surface weather maps you will often see station weather plots. Since meteorologists must convey a lot of information without using a lot of words, plots are used to describe the weather at a station for a specific time. Since meteorologists must convey a lot of information without using a lot of words, plots are used to describe the weather at a station for a specific time.

3. How to Read Surface Weather Maps There are a large number of weather symbols used for station plotting. There are a large number of weather symbols used for station plotting. Some are used for weather elements such as rain, snow, and lightning. Some are used for weather elements such as rain, snow, and lightning. Others represent speed of the wind, types of clouds, air temperature, and air pressure. Others represent speed of the wind, types of clouds, air temperature, and air pressure. All of these symbols help meteorologists depict the weather occurring at a weather observing station. All of these symbols help meteorologists depict the weather occurring at a weather observing station.

4. How to Read Surface Weather Maps In the upper left, the temperature is plotted in Fahrenheit. In the upper left, the temperature is plotted in Fahrenheit. In this example, the temperature is 77°F. In this example, the temperature is 77°F.

5. How to Read Surface Weather Maps Along the center, the cloud types are indicated. Along the center, the cloud types are indicated. The top symbol is the high-level cloud type followed by the mid-level cloud type. The top symbol is the high-level cloud type followed by the mid-level cloud type. The lowest symbol represents low-level cloud over a number which tells the height of the base of that cloud (in hundreds of feet) The lowest symbol represents low-level cloud over a number which tells the height of the base of that cloud (in hundreds of feet)

6. How to Read Surface Weather Maps In this example, the high level cloud is Cirrus, the mid-level cloud is Altocumulus, and the low- level cloud is cumulonimbus with a base height of 2000 feet. In this example, the high level cloud is Cirrus, the mid-level cloud is Altocumulus, and the low- level cloud is cumulonimbus with a base height of 2000 feet.

7. How to Read Surface Weather Maps At the upper right is the atmospheric pressure reduced to mean sea level in millibars (mb) to the nearest tenth with the leading 9 or 10 left off. At the upper right is the atmospheric pressure reduced to mean sea level in millibars (mb) to the nearest tenth with the leading 9 or 10 left off. In this example, the pressure would be 999.8 mb. In this example, the pressure would be 999.8 mb.

8. How to Read Surface Weather Maps On the second row, the far left number is the visibility in miles. On the second row, the far left number is the visibility in miles. In this example, the visibility is 5 miles In this example, the visibility is 5 miles

9. How to Read Surface Weather Maps Next to the visibility is the weather symbol. Next to the visibility is the weather symbol. There are 95 symbols which represent weather that is either presently occurring or has ended within the previous hour. There are 95 symbols which represent weather that is either presently occurring or has ended within the previous hour. In this example, a light rain shower was occurring at the time of observation. In this example, a light rain shower was occurring at the time of observation.

10. How to Read Surface Weather Maps The circle symbol in the center represents the amount of total cloud cover reported in the eighths. The circle symbol in the center represents the amount of total cloud cover reported in the eighths. In this example, 7/8 was covered by clouds. In this example, 7/8 was covered by clouds.

11. How to Read Surface Weather Maps This number and symbol tell how much the pressure has changed in the past three hours and the trend in the change of the pressure during the same period of time. This number and symbol tell how much the pressure has changed in the past three hours and the trend in the change of the pressure during the same period of time. In this example, the pressure was steady then fell (lowered) becoming 0.3 mb lower than it was 3 hours ago. In this example, the pressure was steady then fell (lowered) becoming 0.3 mb lower than it was 3 hours ago.

12. How to Read Surface Weather Maps These lines indicated wind direction and speed rounded to the nearest 5 knots. These lines indicated wind direction and speed rounded to the nearest 5 knots. The longest line, extending from the sky cover plot, points toward the direction that wind is blowing from. The longest line, extending from the sky cover plot, points toward the direction that wind is blowing from. In this example, the wind is blowing from the southwest In this example, the wind is blowing from the southwest

13. How to Read Surface Weather Maps The shorter lines, called barbs, indicate the wind speed in knots (kt). The shorter lines, called barbs, indicate the wind speed in knots (kt). The speed of the wind is determined by the barbs. The speed of the wind is determined by the barbs. Each long barb represents 10kt with short barbs representing 5kt. Each long barb represents 10kt with short barbs representing 5kt. In this example, the station plot contains 2 long barbs so the wind speed is between 20- 24 kt. In this example, the station plot contains 2 long barbs so the wind speed is between 20- 24 kt.

14. How to Read Surface Weather Maps The lowest left corner indicates the dew point temperature. The lowest left corner indicates the dew point temperature. The dew point temperature is the temperature the air would have to cool to become saturated, or in other words reach a relative humidity of 100%. The dew point temperature is the temperature the air would have to cool to become saturated, or in other words reach a relative humidity of 100%. In this example the dew point temperature is 71°F. In this example the dew point temperature is 71°F.

15. How to Read Surface Weather Maps The lowest right area is reserved for the past weather, which is the most significant weather that has occurred within the past 6 hours excluding the most recent hour. The lowest right area is reserved for the past weather, which is the most significant weather that has occurred within the past 6 hours excluding the most recent hour. In this example, there was a shower. In this example, there was a shower.