Effects of Synoptic Surveillance on model forecasts for
25 September 2001 0600 UTC
HUMBERTO.


TRACK AND INTENSITY PERFORMANCE

TRACK (km)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN78.134.189.9999.9999.9999.9999.9999.9999.9999.
AVAL61.111.229.9999.9999.9999.9999.9999.9999.9999.
%IMP22%17%-21%
GFNO60.76.102.321.533.9999.9999.9999.9999.9999.
GFAL70.60.107.275.428.9999.9999.9999.9999.9999.
%IMP-17%21%-5%14%20%
VBNO56.165.320.522.783.9999.9999.9999.9999.9999.
VBAL62.179.342.560.840.9999.9999.9999.9999.9999.
%IMP-11%-8%-14%-7%-7%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-44.-55.-60.9999.9999.9999.9999.9999.9999.9999.
AVAL-35.-49.-55.9999.9999.9999.9999.9999.9999.9999.
%IMP20%11%8%
GFNO-15.-34.-31.-26.-11.9999.9999.9999.9999.9999.
GFAL-18.-28.-31.-19.-7.9999.9999.9999.9999.9999.
%IMP-20%18%0%27%36%
SHNO-5.-19.-29.-17.1.9999.9999.9999.9999.9999.
SHAL-5.-19.-29.-17.0.9999.9999.9999.9999.9999.
%IMP0%0%0%0%100%
DSNO-5.-19.-29.-17.1.9999.9999.9999.9999.9999.
DSAL-5.-19.-29.-17.0.9999.9999.9999.9999.9999.
%IMP0%0%0%0%100%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 25 September 2001 0600 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 25 September 2001 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 25 September 2001 0600 UTC.

Figure 4. 12-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases
for 25 September 2001 0600 UTC.