Hurricane Felix Forecast Verification
Written by Derek Ortt on April 19, 2008

Track forecasts for Hurricane Felix were quite accurate. The mean forecast error, as indicated in Fig. 1, which shows the mean track and intensity forecast errors, shows that the forecast error was well below the 10-year mean of the National Hurricane Center. In addition, the forecasts were very skillful, as defined by the difference between the forecasts and CLIPER. The mean forecast error at 96 hours was 103NM, compared to more than 350NM for CLIPER. The reason why the forecasts had such as high degree of accuracy can be explained best by the fact that Felix remained in the deep tropics and did not encounter any mid-latitude weather systems. Typically, forecasts for westward moving storms in the deep tropical that are free from extra-tropical influences are very small. That said, there was one primary source of error. While initial forecasts, explained in the left panel of Fig. 2, indicated that the system would make landfall in Nicaragua, later forecasts, indicated by the right panel in Fig. 2 indicated a landfall in Honduras, or even passing just north of Honduras and a landfall in Belize. Some of the global forecast models did not capture the strength of the ridge of high pressure to the north of the storm.

In contrast, the intensity forecasts were very poor. The intensification from a depression into a category 5 hurricane in 60 hours was not expected by any of the guidance, or the forecasts. This contributed to much of the error shown in the lower panel of Fig. 1. The second source of error was due to some track forecasts keeping the storm over water until impacting Belize.

Table 1 contains the recommended watches and warnings. A Tropical Storm Warning was recommended about 6 hours before moving over the Windward Islands. The reason why the lead time was a little less than usual was because initial forecasts did not have Felix reaching tropical storm intensity until after moving into the Caribbean. Other watches and warnings were recommended appropriately. A Hurricane Warning was never recommended for the ABC islands despite its very close pas to the north due to forecast confidence and the very small wind field south of the center. The Hurricane Watch was recommended about 39 hours before landfall for Nicaragua. The Hurricane Warning was recommended about 24 hours before landfall, and the Super Hurricane Warning was recommended about 9 hours before landfall.A Hurricane Watch was recommended for Guatemala and Belize. This was due to the small track forecast error and proved to be unnecessary.

For synoptic history, and official watches and warnings, please see the Tropical Cyclone Report on Hurricane Felix.

Mean track and intensity forecast errors for Hurricane Felix (blue). Black and red lines denote the NHC 10-year mean error and CLIPER/SHIFOR respectively.

NWHHC track forecasts (blue) 1 (left) and 7 (right) vs best track (red) for Hurricane Felix

Click Here for individual track/intensity forecast error statistics.

Table 1: Table of Recommended Watches and Warnings

0300 UTC 9/1 Tropical Storm Warning: Grenada, The Grenadines, St. Vincent
1200 UTC 9/1 Tropical Storm Warning: Island of Margarita
1200 UTC 9/1 Tropical Storm Warning Dropped: Grenada, The Grenadines, St. Vincent
1500 UTC 9/1 Hurricane Watch/Tropical Storm Warning: ABC Islands
1500 UTC 9/1: All Caribbean Venezuelan Islands east of 68W
2100 UTC 9/1 Tropical Storm Warning Dropped: Venezuelan Caribbean islands east of 65W
0000 UTC 9/2 Tropical Storm Warning Dropped: Venezuelan Caribbean islands east of 66W
1500 UTC 9/2 Tropical Storm Warning Dropped: Remainder of Venezuelan Caribbean Islands
1800 UTC 9/2 Hurricane Watch/Tropical Storm Warning Dropped: ABC Islands
2100 UTC 9/2 Hurricane Watch Prinzapolka, Nicaragua to Trujillo, Honduras
1200 UTC 9/3 Hurricane WARNING: Prinzapolka, Nicaragua to Trujillo, Honduras
1200 UTC 9/3 Hurricane Watch: Trujillo to Honduras, Guatemala Border
1500 UTC 9/3 Hurricane WARNING: Trujillo to Tela, Honduras
1500 UTC 9/3 Hurricane Watch: Guatemala/Honduras Border to Belize, Mexico Border
2100 UTC 9/3 Hurricane WARNING: Tela to Honduras, Guatemala Border
0410 UTC 9/4 Tropical Storm Warning: Provedencia Island
0600 UTC 9/4 SUPER HURRICANE WARNING: Cayos Miskitos, Nicaragua to Nicaragua/Honduras Border
1200 UTC 9/4 Super Hurricane Warning changed to Hurricane WARNING: Cayos Miskitos, Nicaragua to Nicaragua/Honduras Border
1500 UTC Tropical Storm Warning Dropped; Provedencia
1800 UTC 9/4 Hurricane Watch Dropped; Guatemala and Belize
2100 UTC 9/4 All Watches and Warnings Dropped

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