Effects of Synoptic Surveillance on model forecasts for
Hurricane Dennis.

QuickTime movie of DLM wind analyses
QuickTime movie of DLM wind data initial increments

Assessments for each forecast time at

August 23, 1999				18 Z
August 24, 1999	00 Z*	06 Z	12 Z	18 Z
August 25, 1999	00 Z	06 Z	12 Z	18 Z
August 26, 1999	00 Z*	06 Z	12 Z	18 Z
August 27, 1999	00 Z*	06 Z	12 Z	18 Z
August 28, 1999	00 Z*	06 Z	12 Z	18 Z
August 29, 1999	00 Z*	06 Z	12 Z	18 Z
August 30, 1999	00 Z*	06 Z	12 Z	18 Z
August 31, 1999	00 Z*	06 Z	12 Z
* Synoptic surveillance nominal times

Figure 1a. Track forecast errors for the no dropwindsonde (NO or NN) and the all dropwindsonde (AL) runs for the GFS and GFDL models for the Hurricane Dennis synoptic surveillance mission.

Figure 1b. Track forecast improvements for the GFS and GFDL models for the the Hurricane Dennis synoptic surveillance mission.
(a)

(b)

Figure 2. Forecast errors for the landfall of Hurricane Dennis at Abaco Island, Bahamas, in the (a) cross- and (b) along-track directions for the no dropwindsonde (NO or NN) and the all dropwindsonde (AL) runs for the GFS and GFDL models.
(a)

(b)

Figure 3. Forecast errors for the landfall of Hurricane Dennis at Cape Lookout, NC, in the (a) cross- and (b) along-track directions for the no dropwindsonde (NO or NN) and the all dropwindsonde (AL) runs for the GFS and GFDL models.

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