Understanding the tropical storm forecast charts can help keep you safe.
The minute a tropical storm might even possibly threaten the coast of the U.S., three different weather charts begin appearing across the Internet and being discussed by television weather forecasters. Each chart tells you something different about the pending storm, and taken together they provide a complete picture of the most likely movement and timing of hazardous weather. So le’s take a look at them to see what they each can tell us and how to read each.
NHC Track Forecast Cone
What it tells you: The probability of 50-knot winds in your area in the 120 hours (five days) after the date and time on the forecast.
What you can use it for: Assessing how likely it is that you will get winds of 50 knots or greater in the next five days.
What it doesn’t tell you: Exactly when within those five days you might get those winds.
Variations: Tropical Storm Force Wind Speed Probabilities (34-63 knots/39- 73 mph); Hurricane Force Wind Speed Probabilities (64 knots/74 mph or higher).
What it tells you: The forecast tracks for the storm from different weather models.
What you can use it for: Determining whether the current forecast has a high or low probability of occurring.
What it doesn’t tell you: Exactly where the hurricane is going to track or how strong the winds might be if it reaches you.