CHARLOTTE, N.C. — The National Hurricane Center is responsible for the forecast cones and updated tropical storm and hurricane information throughout the year. Even before a storm forms, areas of thunderstorms and low pressure systems in the Atlantic and Gulf of Mexico are monitored for possible development. Once a storm becomes a tropical depression or potential development is imminent, a Tropical Cyclone Public Advisory will be issued.
Tropical Cyclone Public Advisory:
These Public Advisories are published four times a day. At 5 a.m., 11 a.m., 5 p.m., and 11 p.m. Every 6 hours the National Hurricane Center (NHC) will update a Tropical Depression, Tropical Storm or Hurricanes, forecast cone, watches or warnings, minimum central pressure, forward speed and direction, wind speeds/wind gusts and location.
The most important update in these four updates per day is the change to the forecast path and forecast cone.
At the four times mentioned, the biggest change you will notice is path and the strength forecasted for every 12 hours of its possible path. The forecast cone will go out for 5 days or until the storm is forecasted to dissipate below tropical depression status. The image below is an example of what the NHC will send out.
The S in the circles stands for Tropical Storm. An H will represent hurricane force sustained winds and an M means that at that point, the storm will be a major hurricane. A major hurricane is category 3 or greater (Winds at 111 mph or more). This information comes into our computers and graphics system and we are able to specify the forecasted speed per time frame along the cone.
Intermediate Advisories:
Once there are active coastal watches and warnings, the NHC will increase the updates to every 3 hours. All of the watches and warnings will be updated along with the pertinent storm information will be updated at:
2 a.m., 5 a.m., 8 a.m., 11 a.m., 2 p.m., 5 p.m., 8 p.m., 11 p.m.
The only thing that will not be updated is the forecast cone. Again, that will still only come every 6 hours during the Public Advisories.
When a landfall of a storm is imminent, the National Hurricane Center will issue updated advisories hourly, if not more frequently, as the situation warrants.