Isn't the weather controlled by the heating mass very hot, and then the airflow rises? Why do you say that after the warm front crosses the border, there is a warm air mass to control the sunny day, and the geographical god helps.

Whether it produces rain or not, warm air containing more water vapor needs to rise to do adiabatic movement, and work at high altitude due to low air pressure, releasing latent heat and forming rain.

Under the action of a single warm air mass, there is no phenomenon that warm air climbs with the interface between cold and warm air, so there is no frontal rain.

If it rises by heating, it takes a long time for the sun to shine on the ground, so that the ground temperature rises to a sufficient height, and the heat in the upper and lower air is greater than the gravity of the air itself to complete the heating and rising of the air.

Therefore, basically, this condition can only be achieved when the ground sun shines to 35 degrees in the afternoon (that is, convective thunderstorms in summer) under the edge of subtropical high in summer. In other seasons, especially when cold and warm fronts can meet, the surface temperature can't reach this level, so the warm front will only see a low pressure after crossing the border, but the sky is not cloudy. The weather is still fine.