How often does the NHC do hurricane advisories for a major tropical cyclone like this one? I know for less powerful ones they do advisories at 11 AM, 5 PM, 11 PM, and 5 AM ( ).
When there are no watches or warnings, NHC uses 0300, 0900, 1500, and 2100 UTC. That converts to 5 AM, 11 AM, 5 PM and 11 PM EDT, but you'll see that change an hour back when we go to EST as UTC never changes. When a watch is issued, NHC will do advisories every 3 hours instead of 6. Finally, when a warning is issued, NHC will do advisories every 2 hours and acquire position estimates every hour of the storm.