Effects of Synoptic Surveillance on model forecasts for
22 August 1999 0006 UTC
BRET.


QuickTime movie of DLM wind model forecasts
QuickTime movie of DLM wind data increments


TRACK AND INTENSITY PERFORMANCE

TRACK (km)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN20.24.89.169.225.
AVAL30.10.94.293.407.
%IMP-50%58%-6%-73%-81%
GFNO54.30.52.100.162.
GFAL54.51.56.150.135.
%IMP0%-70%-8%-50%17%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-82.-45.-12.-10.-4.
AVAL-84.-44.-10.-10.-5.
%IMP-2%2%20%0%-25%
GFNO-41.-8.9.13.13.
GFAL-37.5.12.8.14.
%IMP10%38%-33%38%-8%
SHNO5.44.88.88.86.
SHAL6.46.89.90.88.
%IMP-20%-5%-1%-2%-2%
DSNO5.44.28.8.5.
DSAL6.46.28.8.5.
%IMP-20%-5%0%0%0%
Landfall forecasts
23/0000UTC 26.9N 97.4W Central Padre Island, TX 18 h into forecast
LATLONFTIMEERRORLOCATION
AVNN26.7797.3519.515.3 Central Padre Island, TX
AVAL26.9797.3720.08.3 Central Padre Island, TX
%IMP-33%46%
LATLONFTIMEERRORLOCATION
GFNO26.9497.4122.54.6 Central Padre Island, TX
GFAL26.9097.4024.00.0 Central Padre Island, TX
%IMP-33%100%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 22 August 1999 0600 UTC (Hurricane Bret).

Figure 2. Track forecasts for the no dropwindsonde (NO or NN) and the all dropwindsonde (AL) runs for the AVN and GFDL models initialized on 22 August 1999 0600 UTC. The best track is shown in black.

Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 22 August 1999 0600 UTC.

Figure 4. 12-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 22 August 1999 0600 UTC.