Effects of Synoptic Surveillance on model forecasts for
14 September 2003 1200 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 22 23 32 63121176173243314465
AVNO 52 60 60 63 60 87139249333378
%IMP-136%-161%-88% 0%50%51%20%-2%-6%19%
GFNO 52 93113111124190278435487548
GFDL 10 73 89102128195323455490547
%IMP81%22%21% 8%-3%-3%-16%-5%-1% 0%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-86-72-54-45-40-35-33-37 -1 23
AVNO-57-54-32-22-12-14 -4-12 11 5
%IMP34%25%41%51%70%60%88%68%-1000%78%
GFNO-31-25 -4 -6 0 3 1 -7 3 14
GFDL-20-17 -8 -1 -2 3 4 -9 0 17
%IMP35%32%-100%83%und% 0%-300%-26%100%-21%
SHNO 0 8 21 27 21 16 5 -8 3 25
SHIP 0 6 20 24 17 12 0-12 1 25
%IMP 0%25% 5%11%19%25%100%-50%33% 0%
DSNO 0 8 21 27 21 16 5 -8-20 -2
DSHP 0 6 20 24 17 12 0-12-21 -3
%IMP 0%25% 5%11%19%25%100%-50%-5% -50%

Landfall forecasts

18/1700 UTC 34.9N 76.2W Drum Inlet, NC 101.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN38.5375.05116.5416.1York Beach, VA
AVNO39.1274.89112.5483.0Cape May, NJ
%IMP 26% -16%
GFNO38.8175.04100.5446.5Dewey Beach, DE
GFDL37.9475.46 96.5344.2Chincoteague, VA
%IMP-800% 26%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 14 September 2003 1200 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 14 September 2003 1200 UTC.

Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 14 September 2003 1200 UTC.

Figure 4. 12-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 14 September 2003 1200 UTC.