Membrane roofs are susceptible to damage in high winds. Wind can lift a membrane roof from a building and cause it to tear or become damaged. The present roof vent prevents liftoff and damage by reducing the air pressure under the membrane during high winds. The present roof vent has two opposed convex domes separated by a gap. Wind blowing across the roof flows between the domes where it accelerates and creates a region of low pressure according to the Venturi effect. The lower dome has an opening at the gap so that the low pressure is applied to the space under the membrane roof. Therefore, when wind blows across the roof, the vent draws air from under the membrane and the membrane is pressed against the roof, preventing liftoff.