You need warm moist air from Mexico to mix with the dry cool air from the north.
No. Tornadoes can form in relatively cool air. However they form more easily when there is plenty of warm, moist air to fuel the thunderstorms that spawn them.
Warm air is less dense than cool air.
air
cool air is heavier than war air.
a tornado will form
by the time when warm air meets cool air.
clouds form above chimneys as the warm air mixes with the cool air
STatioNary Front :):
Convection
Stationary
Cool air rising through warm air (apex)
occluded
occluded
occluded
STatioNary Front :):
STatioNary Front :):