Originally Posted by
FlyFly
Another question came to my mind. Can you anticipate a "bad weather" which is associated with low pressure with just getting a low QNH from ATC? And stable weather when QNH is high?
Making mini-forecasts can be done using pressure reading alone...but because there are so many factors involved in determining the dominant weather in an area, typically pressure reading isn't enough by itself to anticipate any particular pattern of weather beyond stability.
A good example is Florida in the summer. Pressure is typically higher than standard all summer, day and night, however because of the daily heating and converging sea breezes during the day, thunderstorms develop like clockwork every afternoon in otherwise-stable air / high pressure air. This is another example of how local (mesoscale) weather patterns can overpower larger (synoptic) scale weather patterns.