Effects of Synoptic Surveillance on model forecasts for
17 September 2003 0600 UTC
Isabel.


Quicktime movie of GFS 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
AVNN 58 65 43184361
AVNO 29 48 80194442
%IMP50%25%-86%-5%-22%
GFNO 49 39 21183433
GFDL 22 24 81273500
%IMP55%38%-186%-49%-15%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-38-40-31 -8 -9
AVNO -3-15 -8-11-11
%IMP92%62%74%-38%-22%
GFNO 10 11 18 7 14
GFDL 12 12 15 11 9
%IMP-20%-9%17%-57%36%
SHNO 7 5 4 30 39
SHIP 6 3 0 24 33
%IMP14%40%100%17%15%
DSNO 7 5 4 -6 2
DSHP 6 3-16-10 1
%IMP14%40%-300%-67%50%

Landfall forecasts

18/1700 UTC 34.9N 76.2W Drum Inlet, NC 35.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN34.9976.10 36.5 13.5Ocracoke, NC
AVNO34.8176.60 38.0 37.8Beaufort, NC
%IMP -100% -180%
GFNO34.8276.35 35.0 15.3Little Port, NC
GFDL34.6477.13 37.0 89.7Emerald isle, NC
%IMP und% -486%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 17 September 2003 0600 UTC (Hurricane Isabel).

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 17 September 2003 0600 UTC.

Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 17 September 2003 0600 UTC.

Figure 4. 12-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 17 September 2003 0600 UTC.