Warm Fronts

A warm front is the boundary zone between retreating cold air and the advancing warm air. Again, the warm air overrides the cooler air, forming clouds and precipitation. However, the weather is characterized by rain or showers, not storms. Because the slope of the warm front is not as steep as the cold front, showers form more gradually, preventing latent energy from reaching high altitudes. There is a temperature and humidity increase with the passage of a warm front.

Weather Element	Before passing	While passing	After passing
Winds	South or southeast	Variable	South or southwest
Temperature	Cool to cold, slow warming	Steady rise	Warmer, then steady
Pressure	Usually falling	Leveling off	Slight rise, followed by fall
Clouds	In this order: cirrus, cirrostratus, altostratus, nimbostratus, stratus, and fog; occasionally cumulonimbus in summer	Stratus type	Clearing with scattered stratocumulus; occasionally cumulonimbus in summer
Precipitation	Light to moderate rain, snow, sleet, or drizzle	Drizzle or none	Usually none; sometimes light rain or showers
Visibility	Poor	Poor, but improving	Fair in haze
Dew point	Steady rise	Steady	Rise, then steady