Real Clear Science's Newton Blog offers some helpful tips on understanding some of the things a television weather personality says when discussing weather conditions and forecasts.
They specifically describe what it means to say that a barometer or barometric pressure is such-and-such a figure and either falling or rising. It has to do with the way that old-fashioned barometers used a column of mercury and measured its height, which would vary with the external air pressure. Falling air pressure predicts storms or other bad weather, while rising air pressure indicates clear weather ahead.
Newton is a science blog. So it leaves out that an important factor in understanding your average weatherperson is to remember that he or she is above all a paid employee of a company that wants your viewership. Being such, he or she is not going to do much to counter the not-so-subtle implication that to switch away from the station's coverage of the weather to some other outfit which lacks its ultra-high-tech gizmos and tried-and-true tested and trustworthy TelePrompTer Muppets is to court instant soggy and windy death.