In meteorology, an air parcel that is warm is only so in relation to another parcel. The horizontal movement of warmer air into a location. Contrast with cold advection. The leading edge of an advancing warm air mass that is replacing a retreating relatively colder air mass. Precipitation, in the form of rain, snow, or drizzle, is generally found ahead of the surface front, as well as convective showers and thunderstorms.
Fog is common in the cold air ahead of the front.
Although clearing usually occurs after passage, some conditions may produced fog in the warm air. See occluded front and cold front. HIGH A high pressure system that has its warmest temperatures at or near the center of circulation. Contrast with a cold high. Examples include a cut-off high and an omega block.