Effects of Synoptic Surveillance on model forecasts for
16 September 2003 1800 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 33 59 79 56208425
AVNO 10 24 33 43177378
%IMP70%59%58%23%15%11%
GFNO 24 29 24 64158294
GFDL 35 35 39 80212389
%IMP-48%-21%-63%-25%-34%-32%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-43-36-34-21 -4-11
AVNO-10-15-16 -5 -8-10
%IMP77%58%53%76%-100% 9%
GFNO 6 14 10 15 10 18
GFDL 5 12 14 12 7 16
%IMP17%14%-40%20%30%11%
SHNO -5 3 2 2 29 40
SHIP -5 1 0 0 26 36
%IMP 0%67%100%100%10%31%
DSNO -5 3 2 -3 -8 2
DSHP -6 1 1 0 -4 3
%IMP-20%67%50%100%50%-50%

Landfall forecasts

18/1700 UTC 34.9N 76.2W Drum Inlet, NC 47.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN35.0076.09 49.0 15.0Ocracoke, NC
AVNO35.0076.28 49.0 13.3Little Port, NC
%IMP 0% 11%
GFNO34.7476.65 46.0 44.7Beaufort, NC
GFDL34.7177.08 47.5 83.0Emerald Isle, NC
%IMP 50% -86%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 16 September 2003 1800 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 16 September 2003 1800 UTC.

Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 16 September 2003 1800 UTC.

Figure 4. 12-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 16 September 2003 1800 UTC.