Original: After intensification slowed for a few hours, another round of rapid intensification occurred and Gustav was upgraded to a Category 4 hurricane during a hurricane hunter flight around 1 p.m. EDT (1700 UTC), with 145 mph (215 km/h) winds.
Simplified: After strengthening slowed for a few hours, another round of quick strengthening happened and Gustav was upgraded to a Category 4 hurricane during a hurricane hunter flight around 1pm (EDT), with 145 mph winds.