There are storms off in the distance, and the plane has landed safely. Why is the plane parked on the apron and passengers are not deplaning?
Most likely, there has been lightning detected in the area and airline employees are not allowed on the apron until the danger has cleared. That means the jetway cannot be operated and the baggage cannot be unloaded; the plane will hold in position until it can be safely off-loaded.
Policy regarding employee actions when a lightning detector goes off and when employees are allowed to resume duties may vary between airlines.
For more information on the Precision Lightning Warning System (PLWS) installed at Tampa International Airport, click here.