Effects of Synoptic Surveillance on model forecasts for
18 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 76 75209
AVNO 36110270
%IMP53%-47%-29%
GFNONo forecast available
GFDLNo forecast available
%IMP
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-29 -5 -9
AVNO-10 -5 -5
%IMP66% 0%44%
GFNONo forecast available
GFDLNo forecast available
%IMP
SHNO 3 31 43
SHIP 2 30 40
%IMP33% 3% 7%
DSNO 3 -7 2
DSHP 2 -4 3
%IMP33%43%-33%

Landfall forecasts

18/1700 UTC 34.9N 76.2W Drum Inlet, NC 11.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN35.2275.53 9.5 70.5Hatteras, NC
AVNO35.1076.00 12.0 28.8Ocracoke, NC
%IMP 33% 59%
GFNONo forecast available
GFDL35.1175.87 11.5 38.0Ocracoke, NC
%IMP

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 18 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 18 September 2003 0600 UTC.

Figure 3. Ensemble perturbation variance at the nominal sampling time 18 September 2003 0600 UTC from the previous day NCEP ensemble forecast. The circles represent the dropwindsonde locations.

Figure 4. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 18 September 2003 0600 UTC. The circles represent the dropwindsonde locations.