 A surface weather analysis is a special type of weather map which provides a view of weather elements over a geographical area at a specified time based on information from ground @-@ based weather stations . Weather maps are created by plotting or tracing the values of relevant quantities such as sea @-@ level pressure , temperature , and cloud cover onto a geographical map to help find synoptic scale features such as weather fronts . Surface weather analyses have special symbols which show frontal systems , cloud cover , precipitation , or other important information . For example , an H may represent high pressure , implying fair weather . An L on the other hand may represent low pressure , which frequently accompanies precipitation . Low pressure also creates surface winds deriving from high pressure zones . Various symbols are used not just for frontal zones and other surface boundaries on weather maps , but also to depict the present weather at various locations on the weather map . In addition , areas of precipitation help determine the frontal type and location . 
