National Hurricane Center Forecasting Change

Good Morning,

For those that do not closely follow the National Hurricane Center, they have made a significant change to their forecasting.  In previous years, all updates were based on a “five-day” model; this year, the alerts are based on a seven-day model.  Just in time for the 2023 season, we have our first notice. 


As of this writing, the NHC predicts a 20% chance of tropical development.   It is also important to note that this outlook is based on two time periods, the next 48 hours and the next seven days.  For this outlook, the 48-hour and the 7-day are both 20%.  The NHC will always report the highest chance over the period. There may be a system in the future that may have a 20% chance of development over the next 48 hours but then a 50% chance of development over the 7-day period, so the report for that storm would be 50%.  With a more extended outlook, I suspect that we will have more alerts of tropical development this year than we have had in previous years, but it is likely that more alerts this year will not result in development.  It will be necessary to resist the urge to disregard the NHC alerts because of the sheer volume. Remember, it only takes one storm to be a significant season for those affected. 


Jim Williams, MBA

Public-Private Partnership Operations Officer

Louisiana Business Emergency Operations Center

(Office:  (337) 482-0633