There are really 2 answers to that question:
1.) No one in their right mind would drive that baby in the rain unless
they got caught unexpectedly and;
2.) Current cobra heat extractors channel water over the top of the
radiator shroud. Not ideal, but whatcha gonna do?

The car show at the NY Auto Show had extractor vents that were too open
and would channel moisture into the front of the engine bay. The ones on
the prototypes at Woodward had a tighter mesh and the openings further
up the hood. I assume the Ford engineers were taking water management
into account with this design. People liked the ones at the New York
show better, but they appear much less feasible when driving in rain.