MetEd: Tropical Cyclone Forecast Uncertainty

Why are the NHC track forecasts for tropical depressions and weak tropical storms less accurate compared to those for hurricanes? Choose the best answer.

All of the above

A 2-day forecast shows the position of a tropical cyclone to be about 150 nautical miles away from a location of your interest. How often is the 2-day National Hurricane Center track forecast error smaller and larger than 150 nautical miles? Use the selection box to choose the best answer.

<150 90% >150 10%

By comparing the official forecast track to the actual track of a tropical cyclone, one can determine the __ By comparing the forecasted location of a tropical cyclone at a particular hour to the actual location at the same hour, one can determine the___

Directional error Timing Error

The cone of uncertainty provides information about the areas and locations that will be impacted by landfalling tropical cyclones. The cone of uncertainty depicts where the center of the tropical cyclone could move two-thirds of the time based on historical track forecast errors. The verifying storm positions of the tropical cyclone are expected to remain within the cone roughly one-third of the time. Impacts from tropical cyclones can be experienced well outside of the cone of uncertainty. The cone of uncertainty is one of the tools that can be used by decision-makers as a preparation tool for evacuation decisions.

False True False True True

You are helping a large coastal community to take preparedness actions for a Category 1 hurricane three days out. The community decision-makers have asked you to identify possible impacts. Which of the following answers will you offer taking into account the possible 3-day track error?

It is difficult to determine exact impacts at this time. A small change in the intensity and direction of the storm could have large implications for the impacts. The community could experience damaging winds and significant storm surge but their magnitude cannot be determined at this time. Even so, a Category 1 hurricane is forecast to be in our vicinity in 72 hours.

You are a forecaster in Wakefield, VA. The mayor of Ocean City, MD wants to know if they should start evacuation and other preparations for the forecasted hurricane. What will you tell the mayor?

It is too early to determine exact impacts at this time. However, there is the potential for a major hurricane with destructive winds and life-threatening storm surge to be in the vicinity of the Mid-Atlantic region this weekend. We advise you to monitor the progress of the hurricane as the week unfolds.

Based on what you have learned about tropical cyclone intensity forecast errors, what action should a community take if a Category 2 hurricane is heading toward it?

Prepare for at least a Category 1 hurricane.

It is 5 pm on Friday afternoon, and NHC is forecasting a hurricane to affect your community over the weekend. Tropical-storm-force winds are forecast to begin in 36 hrs. Decision-makers would like to know the time when the tropical-storm-force winds will begin. Which of the following statements will you use to describe when the hazardous conditions would begin?

Tropical-storm-force winds could begin as early as Saturday evening or Sunday morning.