Can warm weather fronts cause thunderstorms?
No, the storm can trigger a cold atmospheric front.
Before the arrival of the warm weather front, we find ourselves in a cool mass of air. The first sign of approaching the warm front is the appearance of high Cirrus clouds, which over time thicken and pass into a homogeneous curtain of Cirrostratus clouds. Then the front line is about 900 km away. Over time, the cloudiness thickens, until the sun’s visibility is not visible. The current cloud clouds characteristic of the mass of cold air are slowly becoming smaller, until they disappear at a distance of about 500 km from the front line. Cirrostratus clouds give way to denser Altostratus and rainy Nimbostratus, of which a distance of about 350 km from the front line begins to drizzle, which gradually passes into a permanent, steady rainfall from the Nimbostratus cloud.
Since the speed of movement of the warm front does not exceed 100 km / day, this rainfall lasts for about 3 days. In the vicinity of the front lines, it ceases to rain, and the warm air that flows in front of the ground causes the precipitation of adventitious mists. From now on, the weather is already typical for warm air mass, that is, weak wind, small temperature fluctuations in the temperature, lack of vertical air movements, layered cloudiness.
Cold fronts cause thunderstorms
The cold weather front usually has a stormy character, and the main type of clouds occurring within this front is cumulonimbus.
Before the arrival of the cold front, we are in a warm mass of air. The first sign of approaching the cold front may be the occurrence of clouds altocumulus lenticularis (altocumulus in the shape of a lens). Just as the hand moved in the water causes the water to waver in front of him, the fast-moving cool front also causes air to ripple, and the clouds are the symptom of it.
At the head of the cold front we have a huge storm cloud cumulonimbus, which sucks the warm air from the front of the front, cleaning them on the occasion of all types of suspensions (characteristic for air in a warm mass). Therefore, during the passage of the cold front, visibility improves significantly. Cumulonimbus itself can not be noticed by poor visibility inside the warm air mass.
The wind, on the other hand, intensifies and changes its direction to the opposite. It’s getting darker, the wind is gusty. The first lightnings may appear. The front cumulonimbus cloud is much more powerful and its lifespan is much longer than that which arises inside a homogenous mass of air due to local overheating of the ground.
A strong storm precipitates and a thunderstorm begins, which passes relatively quickly. The end of the storm means that the front line has already passed.