Whats the momentum of a parked car

A parked car has no momentum, the car has no kinetic energy without motion.
or momentum = 0

Momentum of a parked car is 0 , since it's parked & doen't have any velocity .

You can prove it mathematically :-

P = m×0

P = 0

Jet streams are relatively narrow bands of strong wind in the upper levels of the atmosphere. the winds blow from west to east in jet streams but the flow often shifts to the north and south. jet streams follow the boundaries between hot and cold air. the earth's rotation is responsible for the jet stream as well.