Erica's Answer:
The reason those winds get so strong is because they have a long downhill trek between the Rocky Mountains and the LA Basin in Southern California. The air accelerates and dries out as it moves downhill over the mountains into the valley. Our mountains to the northwest of Philadelphia, such as the Poconos and the Ridge & Valley region of Pennsylvania, aren't nearly as high as the mountains of Southern California, such as the San Gabriel mountains.- Erica
