Complex sentence: As Gene crossed in to TCWC Wellington's area of responsibility cyclone Gene re-intensified in to a category three severe tropical cyclone with winds of 65 knots however this re-intensification only lasted for 12 hours before Gene began to weaken down to 60 knots.
Split into simpler sentences: As Gene crossed in to TCWC Wellington's area of responsibility. Cyclone Gene started to re-intensify becoming a severe tropical cyclone again with peak winds of 65 knots however this re-intensification only lasted for 12 hours before Gene began to weaken down to 60 knots.