Effects of Synoptic Surveillance on model forecasts for
15 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 20 60 98215319394468
AVNO 24 49 89211277317371
%IMP-20%18% 9% 2%13%20%21%
GFNO 40 20 0 35 33 19 49101112
GFDL 22 15 32 59 67 44 56 48 89
%IMP45%25%und%-69%-103%-122%-14%52%21%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-70-51-43-41-37-33-22
AVNO-33-27-20-15-15-15 -7
%IMP53%47%53%63%59%55%68%
GFNO-16 -2 -2 -4 2 4 7 27 36
GFDL-15 -4 -4 5 7 2 5 21 33
%IMP 6%-100%-100%-25%-250%50%29%22% 8%
SHNO 10 21 23 14 12 -4-15 11 25
SHIP 9 20 21 10 5 -8-18 7 21
%IMP10% 5% 9%29%58%-100%-20%35%16%
DSNO 10 21 23 14 12 -4-32-15 -1
DSHP 9 20 21 10 5 -8-31-15 -1
%IMP10% 5% 9%29%58%-100% 3% 0% 0%

Landfall forecasts

18/1700 UTC 34.9N 76.2W Drum Inlet, NC 83.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNNNo landfall forecast
AVNO35.1975.69 94.5 56.5Hatteras, NC
%IMP
GFNO35.1775.84 83.0 44.4Hatteras, NC
GFDL34.9276.54 82.0 31.1Little Port, NC
%IMP und% 30%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 15 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 15 September 2003 0600 UTC.

Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 15 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 15 September 2003 0600 UTC.