The figure to the right shows the forecast track for a hurricane 48 hours from landfall. What area encompasses all of the locations that should be making preparations for the storm? 1. Pensacola to Morgan City 2. Corpus Christi to Key West 3. Morgan City to Tallahassee 4. Port Arthur to St. Petersburg

The correct answer is the entire coast from Port Arthur to St. Petersburg because you have to take into account both the forecast error AND the size of the wind field.

The dotted line in the figure shows the predicted track of the center of the hurricane. The forecast location error at 48 hours is 164 NM. Plotting that distance on either side of the center track gives a margin of error that extends from Morgan City to just beyond Tallahasse, as shown in the figure to the right. This figure is output from the HURREVAC (Hurricane Evacuation) model, which displays a cone depicting the average track error. Inside this cone, every location is equally likely to have the hurricane hit by the end of the forecast period. In practice, forecasters (and the HURREVAC software) usually increase the error band slightly on the right side because hurricanes are tend to be stronger there.

In addition to taking into account the forecast track error, you must also evaluate the size of the wind fields. The reason Answer 3 is not correct is because the track depicted in the top figure is only the track of the eye. It does not show the position of the tropical storm-force and hurricane-force winds. In this particular case, the tropical wind field (the blue circle) is quite large. When projected forward in time to landfall, you can see that the winds could reach as far as Port Arthur on the west or St. Petersburg on the east, depending on where the hurricane finally goes. If the storm were to curve before landfall, any of these locations could be facing problems more serious than 40-mph winds. It pays to pay attention, even if your location is outside the error cone for now.

The picture to the right shows how the storm (Hurricane Opal, 1995) actually looked when it made landfall. Notice that the size of the hurricane force wind field (the red circle) had increased significantly. Also notice that in this particular case the track proved to be quite accurate (although the forward speed and intensity predictions were less so). While those in Port Arthur and St. Petersburg did not get the tropical storm-force winds, there was no way 48 hours in advance to know that would be the case. Making reasonable preparations based on forecast error and the hurricane size is NOT a "wrong" decision, even if you end up outside of the impact area. Failing to take at least some preliminary precautions in case the track shifts to one side or the other of the error cone (and/or the storm speeds up and/or intensifies) is very risky. Remember Don't focus on the eye-look at the size of the wind fields and how they are changing. Don't focus on the forecast track-use the forecast track error estimates and the strike probability table. If your location shows up on the table (or within the HURREVAC error cone), you should be thinking about what actions to take if the track shifts. Don't assume the hurricane will stay at the same speed-monitor the storm and be ready to speed up the timing of your plans. Don't assume the hurricane will stay at its present intensity-plan for one category higher than forecast, particularly if you are within the forecast track error cone.