JACKSONVILLE, Fla. -- – One thing most people think of during hurricane season is the famous forecast cone.
The cone was developed in 2002 by the National Hurricane Center to help convey the future movement of the system and the uncertainty in the track.
But there are a lot of important details the forecast cone does not tell us.
It does not describe size
The forecast cone does not in any way depict the size of the tropical storm or hurricane, and often the system can become much larger than the forecast cone itself.
A great example of this was Hurricane Irma in 2017.
While the forecast cone depicted movement toward the west coast of Florida, the entire peninsula felt large impacts from the system due to its large size.
It is important to note the forecast cone is the forecast of the center of circulation, not the entire complex.
It does not indicate heavy rain and tornadoes
The forecast cone does not predict area of heavy rainfall or the possibility of tornadoes.
Each tropical system is different, and some system produce extreme rainfall hundreds of miles away from the center of the storm.
The tornado threat is also not depicted by the cone. The highest chance for tornadoes will be in the right front quadrant of the complex.
Tornadoes can also occur well away from the center of the tropical storm or hurricane.
It does not depict storm surge or tidal flooding
As residents along the St. Johns River and its tributaries can attest to, storm surge and tidal flooding can occur well away from the system and can occur for multiple days.
The forecast cone does not show any of this.
Storm surge and tidal flooding is based on a variety of factors, including size of the storm, the angle at which the storm is impacting the region, and the tidal cycle.
The forecast cone cannot be used to depict any of these variables.
The forecast cone isn’t set in stone
The National Hurricane Center uses the forecast cone to show where the center of circulation will be 2/3 of the time.
This means 1/3 of the time, the hurricane center expects the center to exit the forecast cone at some point.
Clearly, if the center moves dramatically, the impacts from the tropical storm or hurricane will change dramatically as well.
A great example of this was Hurricane Matthew in 2016.
The center stayed offshore of the area, but earlier forecasts had the center scrapping the east coast of Florida.
This shift kept the very worst of the storm out to sea.
The forecast cone can be used for depict movement, but the cone should not be used to show size of the system, specific impacts in an area, and the cone is never 100% accurate.
Hurricane season begins on June 1.