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Weather Maps

Graphic Weather Analyses
Flight Service Stations and weather services offices offer a wide variety of pictorial views of the weather. These charts and maps provide lots of information on large-scale weather patterns and trends.

Surface Analysis Chart (or Surface Weather Chart) depicts the weather conditions as they were a few hours earlier to the time stamped on the chart. These charts are developed every 3 hours. Reviewing this chart gives a picture of atmospheric pressure patterns, locations of high and low pressure systems as well as frontal movements.


Click the image to view the entire chart.

Perhaps the most useful information to a pilot planning a flight during preflight is the Weather Depiction Chart. This is actually a simplified version of the weather surface chart. This chart is also generated every 3 hours. It contains information on frontal activity and has an abbreviated version of station models. It does not contain as much detailed information as the surface weather chart, but offers pilots a way to easily and quickly scan for adverse weather conditions.


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Special weather radar systems can detect certain types of weather phenomena. These radar systems emit pulses of radar energy from a rotating antenna. If the signals encounter precipitation, they are reflected back to the antenna as echoes. These are then graphically depicted displaying the strength and location of the precipitation. This radar detection does not detect all cloud formations, only frozen or liquid forms of precipitation. It will not detect fog or the actual tops of rain clouds. The radar summary chart has limitations in that it only displays the conditions that existed at the time recorded on the chart. Remember that thunderstorms can develop rapidly and recently developed thunderstorms might not be displayed.


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The low level significant weather prognostic chart is different from the three previous charts described in that it is a forecast chart (not an observation chart). The "prog" chart is issued four times daily and provides a 12-hour and a 24-hour weather forecast for a given region. It also, only covers from the surface up to the 400-millibar pressure level (24,000 feet in altitude). It is to be used only in planning flights below 24,000 feet.


Click the image to view the entire chart.