 A wide variety of weather can be found along an occluded front , with thunderstorms possible , but usually their passage is associated with a drying of the air mass . Within the occlusion of the front , a circulation of air brings warm air upward and sends drafts of cold air downward , or vice @-@ versa depending on the occlusion the front is experiencing . <unk> and clouds are associated with the trowal , the projection on the Earth 's surface of the tongue of warm air aloft formed during the occlusion process of the depression . 
