Effects of Synoptic Surveillance on model forecasts for
30 August 2004 1200 UTC
Frances.


Quicktime movie of AVN 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 59 39 24 61 93116 107 46 10 54
AVNO 31 42 56 70 84 56 23 49 51141
%IMP47% 8% -133%-15%10%52%79% 7%-410%-161%
GFNO 15 47 46 30 60 60115173259 354
GFDL 10 11 15 15 39 54 97143223 340
%IMP33% 77% 67%50%35%10%16%17%14% 4%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-72-77-78-78-75-75-59-47-23-25
AVNO-70-72-78-76-76-79-62-47-25-30
%IMP 3% 6% 0% 3%-1%-5%-5% 0%-9%-20%
GFNO 5 1 -2 -8 -6-22-13 -7 9 -3
GFDL 8 6 -4 -6-13-22-18 -2 11 2
%IMP-60%-500%-100%25%-117% 0%-39%71%-22%33%

Landfall forecasts

02/1930 UTC 24.0N 74.5W San Salvador Island, Bahamas 79.5 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN24.7974.30 86.0 90.1Well offshore San Salvador Island, Bahamas
AVNO24.0174.49 82.5 1.5San Salvador Island, Bahamas
%IMP 54% 98%
GFNO23.9474.56 76.0 9.0San Salvador Island, Bahamas
GFDL24.0374.49 76.5 3.5San Salvador Island, Bahamas
%IMP 14% 61%
03/0530 UTC 24.6N 75.6W Northern end of Cat Island, Bahamas 89.5 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN25.2476.25 98.5 96.7Central Eleuthera Island, Bahamas
AVNO24.4475.53 89.5 19.1Central Cat Island, Bahamas
%IMP 100% 80%
GFNO24.5175.56 82.0 10.8Northern tip of Cat Island, Bahamas
GFDL24.8075.60 84.0 22.2Northern tip of Cat Island, Bahamas
%IMP 27%-106%
03/1000 UTC 25.1N 76.1W Eleuthera Island, Bahamas 94.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN25.2476.25 98.5 21.7Central Eleuthera Island, Bahamas
AVNO24.7976.29 94.5 39.4Southern tip of Eleuthera Island, Bahamas
%IMP 88% -82%
GFNO24.8476.16 85.5 29.5Southern Eleuthera Island, Bahamas
GFDL25.3976.56 90.0 56.3Northern tip of Eleuthera Island, Bahamas
%IMP 53% -91%
04/1000 UTC 26.6N 78.2W Grand Bahama Island, Bahamas 118.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN26.5678.54117.0 34.1Grand Bahama Island, Bahamas
AVNO26.3378.83114.0 69.5Grand Bahama Island, Bahamas
%IMP-300%-104%
GFNO26.5378.61101.0 41.5Grand Bahama Island, Bahamas
GFDL26.7078.30102.0 14.9Grand Bahama Island, Bahamas
%IMP 6% 67%
05/0430 UTC 27.2N 80.2W South end of Hutchinson Island, FL 136.5 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN No landfall forecast
AVNONo landfall forecast
%IMP
GFNO28.9280.80118.5199.9Edgewater, FL
GFDLNo landfall forecast
%IMP
06/1800 UTC 30.1N 84.0W Mouth of Aucilla River, FL 174.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN No landfall forecast
AVNONo landfall forecast
%IMP
GFNONo landfall forecast
GFDLNo landfall forecast
%IMP

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 30 August 2004 1200 UTC (Hurricane Frances).

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 30 August 2004 1200 UTC.

Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 30 August 2004 1200 UTC.

Figure 4. 12-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 30 August 2004 1200 UTC.