Precipitation Along a Warm Front
warm moist air overriding colder air

The animation below is a sequence of vertical cross sections depicting the development of precipitation ahead of and along a warm front. The region shaded in blue represents a colder air mass while the yellow shading indicates the warm moist air behind the warm front (solid red line).

Animation by: Hall

The frontal zone slopes up and over the colder air mass ahead of it. Warm air rides along the front (up and over the cold air mass), cooling as it rises, producing clouds and precipitation in advance of the surface warm front. Because the lifting is very gradual and steady, generally wide spread and light intensity precipitation develops ahead of a warm front.

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Credits and Acknowledgments for WW2010.
Department of Atmospheric Sciences (DAS) at
the University of Illinois at Urbana-Champaign.