Warm fronts are a shallower and
more gentle change of air mass than cold fronts. Warm air behind
the front replaces the cooler air ahead of the front. Warm fronts
move very slowly (roughly 10 knots). The polar front jet (PFJ) runs parallel
to the warm front on the cold side.
The weather associated with a warm front occurs primarily
ahead of the front in the cooler air. It is primarily stratiform and continuous.
Cumuliform clouds and thunderstorms can also be embedded in these clouds.
Visibility is poor before passage and improves only slightly afterwards.
Pressures fall gradually ahead of the front. Surface pressure can rise
slowly or become steady after passage, but will fall again as the following
cold front approaches. Surface winds are usually from the southeast before
passage, and rotate clockwise to become gusty southwest after passage (veering