Convective Nocturnal Thunderstorms

Convective nocturnal thunderstorm activity over water occurs over the Gulf from May through September. They most often occur 25-50 nm south of the coast during July and August. 

Activity begins to develop after 2200 local. Cumulus humulus gradually develop into thunderstorm activity by  0400 local.  Thunderstorm activity begins to dissipate at 0900 local. By 1100 local most thunderstorm activity has dissipated and skies are generally clear skies over the Gulf by 1200 local. The normal movement of  nocturnal thunderstorm activity is a slow drift to the north. 

Early in the season, dissipation of the thunderstorm activity usually begins before the thunderstorm activity reaches land. When this is the case, only light rain and mid-level cloudiness reach the coast. 

As the season progresses, the water adjacent to the coast becomes warmer. Thunderstorm activity reaches the immediate coastline before dissipation, but rarely moves more than 5 miles inland. KNPA experiences brief periods of ceilings below 1,000' and visibility below 5 miles. Surface wind gusts are minimal with a maximum of less than 30 knots. 

When 500 mb or 700 mb troughs move over the local area, thunderstorm activity increases, prevails longer, and on occasion produces funnel clouds and waterspouts along the immediate coast. 

Perdido Bay Nocturnal Thunderstorms are a local and seasonal type of convective nocturnal thunderstorm. Nocturnal thunderstorm activity occurs over Perdido Bay (west of KNPA) from May through October. This activity begins about 0300 local and reaches its maximum intensity shortly after sunrise. Movement of the storm (if any) takes the storm over land. Dissipation of storm activity begins as soon as landfall is reached.

Concept Mapping Toolkit
Insitute for Human and Machine Cognition
The University of West Florida