Complex sentence: Strong gusts up to 248 km/h (154 mph) left nearly the entire island without power for several days, disrupting the water system and preventing the island-based JTWC from issuing advisories for 11 days.
Split into simpler sentences: Strong gusts up to 248 km/h (154 mph) left nearly the entire island without power for several days. The outages disrupted the water system and prevented the island-based JTWC from issuing advisories for 11 days.