Keywords: NWS weather fronts.svg Weather fronts cold front warm front stationary front occluded front surface trough squall line dry line tropical wave trowal Trough of warm air aloft by http //avalancheinfo net/fixed/weather/glossaries/advanced/advdefs/fronts html Canadian Avalanche Association and http //www eumetcal org/resources/ukmeteocal/rapid_cyclo/www/english/glossary/trowalca htm World Meteorological Organisation w en Image NWSweatherfronts gif http //www wpc ncep noaa gov/html/fntcodes2 shtml Hydrometeorological Prediction Center Camp Springs MD Updated with Trowal on 2013-08-28 2006-08-15 cs User -xfi- PD-USGov Atmospheric front symbols |