Effects of Synoptic Surveillance on model forecasts for
15 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 37 45106173201176312574
AVNO 44 49 31 66 44 14148165
%IMP19%-9%71%62%78%92%53%71%
GFNO 0 24 24 33 96177124 56
GFDL 30 53 88114168265217 91
%IMPund%-121%-267%-336%-106%-50%-75%63%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-52-45-41-38-35-25 -3 1
AVNO-24-22-19-20-20 -9-13 -8
%IMP54%51%54%47%43%64%-333%-700%
GFNO 4 3 0 10 10 -6 -2 29
GFDL 9 2 4 10 12-22 -2 36
%IMP-125%50%und% 0%-20%267% 0%-24%
SHNO 9 15 14 15 8 1 23 33
SHIP 8 13 10 8 -2 -9 13 22
%IMP11%13%29%47%75%-800%43%33%
DSNO 9 15 14 15 8 1 -7 2
DSHP 8 13 10 8 -2-22-12 0
%IMP13%13%29%47%75%-2100%-71%100%

Landfall forecasts

18/1700 UTC 34.9N 76.2W Drum Inlet, NC 71.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN34.7576.74 77.5 52.0Morehead City, NC
AVNO35.0076.30 72.0 14.4Little Port, NC
%IMP 85% 72%
GFNO35.0777.01 68.0 76.1Emerald Isle, NC
GFDL34.5277.48 66.0124.3Ocean City Beach, NC
%IMP -67% -63%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 15 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 15 September 2003 1800 UTC.

Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 15 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 15 September 2003 1800 UTC.