Miami ? The National Hurricane Center said Tuesday it will begin issuing storm watches and warnings about half a day sooner in the biggest change to its warning system in decades.

When a storm is approaching land, forecasters will now send watches advising that tropical storm conditions could be expected there in 48 hours, instead of 36 hours. Warnings of tropical storm or hurricane conditions will be issued 36 hours ahead, not 24 hours.

The changes apply to both the Atlantic hurricane season from June 1 to Nov. 30 and the eastern Pacific season from May 15 to Nov. 30.