“In the Cone” - What does it mean to be in the hurricane forecast cone?

The forecast cone for Ian comes up into Virginia. So, what does that cone mean?

11 a.m. forecast track from 9/27/2022

ROANOKE, Va. – Each hurricane season, you notice our weather team posting graphics and maps of the hurricane forecast cone.

In case you don’t know what it means, we’re here to help!

What does the cone mean?

This map was developed by NOAA’s National Hurricane Center, and it’s a way to convey the path of a tropical system but also the level of uncertainty that exists within a long-range forecast.

The cone represents where the center of the storm can be at a given point in time. Therefore, the wider the cone - the more uncertainty there is in the track of the storm.

The width of the cone does not represent how far the storm’s impact will stretch.

Keep reading for more on that.

Hurricane anatomy

Impacts from a tropical system stretch out from its center.

A tropical system oftentimes has four quadrants from the center of a storm. The eastern half is where the air rises more and where there’s more friction between land and ocean. Therefore, you tend to get more rain, flooding and tornadoes in that half.

Anatomy of a hurricane - its four quadrants

The northwestern side still sees enough rising air to generate rain, a gusty wind and possible flooding.

On the southwest side, the air is sinking. While still breezy, it’s generally the driest quadrant of any tropical system.

Will we see severe weather with Ian?

The short answer to the question above is this: The threat for severe weather is low but not zero.

For this, I look back to previous storms that produced damaging wind, major flooding and/or tornadoes. These storms are Michael (2018), Isaías (2020) and Ida (2021).

In each of these storms, the air was warmer and more conducive to thunderstorm development. These storms had more forward speed, and they were either a tropical depression or a tropical storm by the time they passed through Virginia.

In Ian’s case, we’ll be cooler - in the 60s. The storm will be moving very slowly over land, and it likely won’t be very close in proximity.

Tropical systems in the past few years and how they compare to Ian

So while the tornado or damaging wind threat is low Saturday and Sunday afternoons, it can never be ruled out due to friction forces between the land and the ocean.

Stay with our updates that we push frequently to our weather app.


About the Author:

Meteorologist Chris Michaels is an American Meteorological Society (AMS) Certified Broadcaster, forecasting weather conditions in southwest Virginia on WSLS 10 News from 5 a.m. to 7 a.m. weekdays on Virginia Today.