Effects of Synoptic Surveillance on model forecasts for
13 September 2001 1800 UTC
GABRIELLE.


Quicktime movie of AVN DLM wind model forecast
Quicktime movie of DLM wind data increment


TRACK AND INTENSITY PERFORMANCE

TRACK (km)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN91.177.263.335.220.220.240.179.49.251.
AVAL78.138.198.193.123.143.210.178.268.509.
%IMP14%22%25%42%44%35%13%1%-447%-103%
GFNO60.157.264.348.343.367.436.533.566.569.
GFAL60.157.246.349.382.480.626.737.767.737.
%IMP0%0%7%0%-11%-31%-44%-38%-36%-30%
VBNO70.63.170.365.733.966.1128.1363.9999.9999.
VBAL70.54.174.373.746.963.1140.1398.9999.9999.
%IMP0%14%-2%-2%-2%0%-1%-3%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-17.-7.-6.-14.-16.-16.-25.-28.-19.-28.
AVAL-17.-7.-8.-11.-12.-16.-22.-29.-17.-23.
%IMP0%0%-33%21%25%0%12%-4%11%18%
GFNO32.52.40.12.14.32.38.36.42.23.
GFAL28.55.40.13.8.16.29.26.37.19.
%IMP13%-6%0%-8%43%50%24%28%12%17%
SHNO7.21.34.34.31.26.12.0.8.-2.
SHAL7.21.33.34.30.25.11.-1.6.-4.
%IMP0%0%3%0%3%4%8%und25%-100%
DSNO7.21.0.-10.-13.-18.-32.-44.-36.9999.
DSAL7.21.0.-10.-13.-18.-33.-45.-38.9999.
%IMP0%0%0%0%0%0%-3%-2%-6%

Landfall forecasts

14/1200UTC 27.1N 82.6W Venice, FL 18 h into forecast
MODELLATLONTIMEERRORLOCATION
AVNN28.6482.6546.0171.2 Weeki Wachee Gardens, FL
AVAL28.4982.6638.5154.5 Hernando Beach, FL
%IMP27%10%
GFNO29.5383.4039.0281.1 W of Gainesville, FL
GFAL29.4383.2837.5267.3 Horseshoe Beach, FL
%IMP7%5%
VBNO27.8882.6122.086.7 Gandy, FL
VBAL27.8882.5322.086.9 Tampa, FL
%IMP0%0%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 13 September 2001 1800 UTC
Tropical Depression #15.

Figure 2. Track forecasts for the no dropwindsonde (NO or NN) and the all dropwindsonde (AL) runs for the AVN, GFDL, and VBAR models initialized on 13 September 2001 1800 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 13 September 2001 1800 UTC.

Figure 4. 12-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases
for 13 September 2001 1800 UTC.