Effects of Synoptic Surveillance on model forecasts for
28 August 1999 0600 UTC
DENNIS.


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
AVNN35.45.78.122.167.134.264.333.462.494.
AVAL49.107.124.180.254.295.210.235.328.327.
%IMP-40%-138%-59%-48%-52%-120%20%29%29%34%
GFNO45.69.93.149.242.170.111.287.421.569.
GFAL29.50.61.144.294.322.211.302.403.558.
%IMP36%28%34%3%-21%-89%-90%-5%4%2%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-56.-53.-52.-53.-40.-29.-16.-4.-5.-4.
AVAL-38.-39.-33.-36.-20.-22.-12.9.10.14.
%IMP32%26%37%32%50%24%25%-125%-100%-250%
GFNO3.17.23.20.24.15.16.26.1.-17.
GFAL10.18.25.21.17.7.17.19.1.-9.
%IMP-233%-6%-9%-5%29%53%-6%27%0%47%
SHNO-15.-10.-8.-7.0.2.13.29.35.39.
SHAL-15.-12.-10.-9.-4.-2.9.25.30.33.
%IMP0%-20%-25%-29%und%0%31%14%14%15%
DSNO-15.-10.-8.-7.0.2.13.29.35.39.
DSAL-15.-12.-10.-9.-4.-2.9.25.30.33.
%IMP0%-20%-25%-29%und%0%31%14%14%15%

Landfall forecasts

04/2100UTC 34.8N 76.5W Cape Lookout National Seashore, NC 183 h into forecast
MODELLATLONTIMEERRORLOCATION
AVNN No landfall forecast
AVAL No landfall forecast
%IMP
GFNO38.2975.12102.5406.8 Ocean City, MD
GFAL35.2375.6082.594.8 Hatteras, NC
%IMP-23%77%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 28 August 1999 0600 UTC (Hurricane Dennis).

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 28 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 28 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 28 August 1999 0600 UTC.