The pilot reported that, due to deteriorating weather along his route of flight, he diverted to land at a nearby airport. As he overflew the runway to determine wind direction, he noticed an airplane was parked on the approach end of runway 19 so he decided to land on runway 01 with a 6-knot quartering right tailwind. The pilot reported that after touchdown on the wet runway, he applied heavy braking. The pilot believed that one of the landing gear wheels might have locked up or skidded on a wet area, while the other wheel did not. The airplane subsequently veered off from the runway centerline. The pilot reduced braking to regain directional control, but the airplane overran the runway and the left wing impacted a metal pole. The airplane's left-wing forward spar was substantially damaged. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation.