Along the coastal area of the southern states, the development of stratocumulus clouds during the early morning is typical. These clouds tend to dissipate during the middle of the morning and immediately reform in the shape of scattered cumulus. The continued development of these clouds leads to scattered showers and thunderstorms during the late afternoon. Ceilings become unlimited with the development of the cumulus clouds. Flying con-ditions are generally favorable despite the shower and thunderstorm conditions, since the convective activity is scattered and can be circumnavigated.
Visibility is usually good except near sunrise when the air is relatively stable over land.
When mT air moves slowly northward over the continent, ground fogs frequently form at night. Sea fogs develop whenever this air flows over a relatively cold current such as that occur-ring off the east coast. The notorious fogs over the Grand Banks of Newfoundland are usually formed by this process. In late summer, the Bermuda high intensifies at times and seems to retrograde westward. This results in a general flow of mT air over Texas, New Mexico, Arizona, Utah, Colorado, and even southern California.