Hurricane Dean Forecast Verification
Written by Derek Ortt on June 3, 2008

Track forecasts for Hurricane Dean were below those of CLIPER and similar to the long-term NHC mean track forecast error. This indicated that the forecasts demonstrated significant skill. The greatest skill was shown after the 48 hour time period. CLIPER errors were greater than 200NM for the 72 hour period and approached 600NM for the 120 hour period. In contrast, the mean forecast errors for Dean were under 300NM for the 120 hour time period. The upper panel in Fig. 1 shows the mean track error for Dean and those of CLIPER and the 10-year NHC mean. The greatest source of error occurred when Dean was in the Caribbean Sea. Prior to entering the Caribbean, the forecasts for Dean were very accurate. Figure 2 (left panel) shows forecast track 7 and the best track. Dean moved very close to this forecast track. However, once Dean moved into the Caribbean, there was a northward bias in the forecasts. Figure 2 (right panel shows this, which indicates a landfall in Jamaica, a second landfall near Cozumel, and a final landfall just south of the US/Mexican Border.

The intensity forecasts also showed skill compared to SHIFOR; however, at the longer time periods, they exceeded the NHC 10-year mean error. There were two main sources of error. The first was the intensification into a category 5 in the eastern Caribbean was not expected. IN fact, operationally, Dean was analyzed as a category 4 hurricane at that time. The second was due to the forecasts keeping Dean offshore as it approached its final landfall due to the northward track bias.

The recommended watches and warnings were issued appropriately along the path and can be found in Table 1. The only concern was that the Hurricane Warning for the Lesser Antilles was recommended a little less than 24 hours prior to landfall and the Watch less than 36 hours (30 and 21 hours respectively). In retrospect, the Watch could have been recommended 6 hours before and the Warning 3 hours earlier.

For synoptic history and official watches and warnings, please see the National Hurricane Center Tropical Cyclone Report

Figure 1: Mean Track (upper) and intensity (lower) error for Hurricane Dean. The blue line denotes the NWHHC forecast, the black the NHC 10-year mean error, and the red denotes CLIPER/SHIFOR.

NWHHC forecast track (blue) and best track (red) for Hurricane Dean. Left panel is forecast 7 and right is forecast 12

Click Here for individual track/intensity forecast error statistics.

Table 1: Table of Recommended Watches and Warnings

0300 UTC 8/16 Hurricane Watch: Barbados, St. Lucia, Martinique, Dominica, Guadeloupe
0900 UTC 8/16 Hurricane Watch/Tropical Storm Warning: Barbados
1200 UTC 8/16 Hurricane WARNING: St. Lucia, Martinique, Dominica
1500 UTC 8/16 Hurricane WARNING: Guadeloupe
1500 UTC 8/16 Hurricane Watch: All Leeward Islands north of Guadeloupe to St. Martin
0000 UTC 8/17 Hurricane Watch/Tropical Storm Warning: North of Guadeloupe to St. Martin
0300 UTC 8/17 Hurricane Watch: South coast of Dominican Republic and Haiti
0900 UTC 8/17 Tropical Storm Warning: Puerto Rico and U.S. Virgin Islands
1500 UTC 8/17 Hurricane WARNING: South coast of Haiti
1500 UTC 8/17 Hurricane Watch/Tropical Storm Warning: South coast of Dominican Republic
1500 UTC 8/17 Hurricane Watch: Jamaica
1500 UTC 8/17 Tropical Storm Warning: British Virgin Islands 1500 UTC 8/17 Hurricane Watch/Tropical Storm Warning Dropped: Barbados
1500 UTC 8/17 Hurricane Watch/Tropical Storm Warning to Tropical Storm Warning: North of Guadeloupe to St Martin
1500 UTC 8/17 Hurricane Warning to Tropical Storm Warning: St. Lucia to Guadeloupe
2100 UTC 8/17 Hurricane WARNING: South coast of Dominican Republic west of 70W
2100 UTC 8/17 Tropical Storm Warning Dropped: South of Guadeloupe
0000 UTC 8/18 Tropical Storm Warning Dropped: Leeward Islands
1200 UTC 8/18 Tropical Storm Warning Dropped: Virgin Islands and Puerto Rico
1500 UTC 8/18 Hurricane WARNING: Jamaica
1500 UTC 8/18 Hurricane Watch: South coast of Cuba east of 78W and Cayman Islands
2100 UTC 8/18 Hurricane Watch/Tropical Storm Warning: All of Haiti north of Port Au Prince
0300 UTC 8/19 Hurricane Watch/Tropical Storm Warning: South coast of Cuba east of 78W
0300 UTC 8/19 Hurricane Watch: South coast of Cuba between 78-80W
0300 UTC 8/19 Hurricane Watch/Tropical Storm Warning to Tropical Storm Warning: South coast of Dominican Republic east of 70W
0900 UTC 8/19 Hurricane WARNING: Cayman Islands
0900 UTC 8/19 Hurricane Warning to Tropical Storm Warning: South coast of Dominican Republic west of 70W
0900 UTC 8/19 Tropical Storm Warning Dropped: South coast of Dominican Republic east of 70W
1500 UTC 8/19 Hurricane Watch: Belize City to Cancun, Mexico
1500 UTC 8/19 Hurricane Warning and Hurricane Watch/Tropical Storm Warning changed to Tropical Storm Warning: All of Haiti
1800 UTC 8/19 Hurricane Watch Dropped: South coast of Cuba between 78-80W
0000 UTC 8/20 Hurricane WARNING:/Super Hurricane Watch: Grand Cayman Island
0300 UTC 8/20 Hurricane Watch Extended: Cancun to Merida, Mexico
0300 UTC 8/20 Tropical Storm Warning: south coast Cuba between 78-80W
0300 UTC 8/20 Hurricane Watch/Tropical Storm Warning to Tropical Storm Warning: South coast of Cuba east of 78W
0300 UTC 8/20 Tropical Storm Warning Dropped: Haiti
0900 UTC 8/20 Hurricane WARNING: Belize City to Cancun
0900 UTC 8/20 Hurricane Watch Extended: Merida to Veracruz, Mexico
0900 UTC 8/20 Hurricane Warning/Super Hurricane Watch to Hurricane WARNING: Grand Cayman Island
0900 UTC 8/20 Hurricane Warning Dropped: Jamaica
0900 UTC 8/20 Tropical Storm Warning Dropped: Cuba
2100 UTC 8/20 SUPER HURRICANE WARNING: Belize/Mexico Border to Tulum, Mexico
2100 UTC 8/20 Hurricane WARNING: Extended from Cancun to Veracruz
2100 UTC 8/20 Hurricane Watch: Veracruz to US/Mexican Border
2100 UTC 8/20 Tropical Storm Warning: Belize City to Guatemala/Honduras Border
1500 UTC 8/21 Hurricane WARNING: Extended from Veracruz to Tampico
1500 UTC 8/21 All Watches and Warnings Dropped: South and east of Merida
1500 UTC 8/21 Hurricane Watch Dropped: North of La Pesca, Mexico
2100 UTC 8/21 Hurricane Warning Dropped: Merida to Campeche, Mexico
0900 UTC 8/22 Hurricane Watch/Tropical Storm Warning: Tampico to La Pesca
2100 UTC 8/22 All Watches/Warnings Dropped

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