Effects of Synoptic Surveillance on model forecasts for
15 September 2001 1200 UTC
GABRIELLE.

Quicktime movie of AVN DLM wind model forecastbr> Quicktime movie of DLM wind data increment

TRACK AND INTENSITY PERFORMANCE
TRACK (km)
MODEL	12 h	24 h	36 h	48 h	60 h	72 h	84 h	96 h	108 h	120 h

AVNN	44.	80.	172.	361.	523.	701.	838.	858.	9999.	9999.
AVAL	44.	72.	187.	390.	548.	724.	882.	1002.	9999.	9999.
%IMP	0%	10%	-9%	-8%	-5%	-3%	-5%	-17%

GFNO	147.	310.	532.	718.	871.	949.	1055.	1153.	1502.	1759.
GFAL	204.	381.	576.	839.	1011.	1114.	1292.	1428.	1882.	2252.
%IMP	-39%	-23%	-8%	-17%	-16%	-17%	-22%	-24%	-25%	-28%

VBNO	53.	49.	105.	209.	301.	366.	316.	166.	429.	664.
VBAL	53.	49.	105.	218.	315.	381.	354.	200.	435.	642.
%IMP	0%	0%	0%	-4%	-5%	-4%	-12%	-20%	-1%	3%
INTENSITY (kt)
MODEL	12 h	24 h	36 h	48 h	60 h	72 h	84 h	96 h	108 h	120 h

AVNN	-9.	-16.	-31.	-41.	-27.	-25.	-32.	-31.	9999.	9999.
AVAL	-9.	-16.	-32.	-41.	-26.	-26.	-32.	-33.	9999.	9999.
%IMP	0%	0%	-3%	0%	4%	-4%	0%	-6%

GFNO	-8.	-6.	18.	26.	51.	57.	54.	52.	36.	20.
GFAL	-12.	-5.	-14.	11.	38.	48.	46.	45.	47.	35.
%IMP	-50%	17%	22%	58%	25%	16%	15%	13%	-31%	-75%

SHNO	-7.	-8.	-16.	-22.	-13.	-9.	-12.	-11.	-12.	-15.
SHAL	-7.	-8.	-16.	-21.	-12.	-8.	-12.	-12.	-14.	-19.
%IMP	0%	0%	0%	5%	8%	11%	0%	-9%	-17%	-27%

DSNO	-7.	-8.	-16.	-22.	-13.	-9.	-12.	-11.	-12.	-15.
DSAL	-7.	-8.	-16.	-21.	-12.	-8.	-12.	-12.	-14.	-19.
%IMP	0%	0%	0%	5%	8%	11%	0%	-9%	-17%	-27%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 15 September 2001 1200 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 15 September 2001 1200 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 15 September 2001 1200 UTC.

Figure 4. 12-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases
for 15 September 2001 1200 UTC.