Effects of Synoptic Surveillance on model forecasts for
02 September 2004 1800 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 38 24 39 15 32 45 73 0 15173
AVNO 30 39 56 23 60 94129 40100186
%IMP29%-63% -44%-53%-88%-109%-77%und%-567%-9%
GFNO 11 75 35 73 98148226191221 370
GFDL 23 35 39 24 37 99161135104 171
%IMP-109% 53% 11%67%62%33%29%29%53%54%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-55-47-32-22-24 -2 -6 1 0 -4
AVNO-26-23 -9-11-17 2 -1 4 -2 -3
%IMP53%51%72%50%29% 0%83%-300%und%25%
GFNO 15 18 21 19 7 36 29 24 11 18
GFDL 5 12 20 12 3 22 26 28 12 10
%IMP67%33% 5%37%57% 39%10%-16%-9%44%

Landfall forecasts

03/0530 UTC 24.6N 75.6W Northern end of Cat Island, Bahamas 11.5 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN24.5275.59 8.5 8.9Cat Island, Bahamas
AVNO24.6675.64 9.5 7.8Cat Island, Bahamas
%IMP 33% 12%
GFNO24.6875.62 11.0 9.1Cat Island, Bahamas
GFDL24.4975.56 9.0 12.9Cat Island, Bahamas
%IMP-400% -42%
03/1000 UTC 25.1N 76.1W Eleuthera Island, Bahamas 16.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN25.1776.26 14.5 17.9Eleuthera Island, Bahamas
AVNO25.2276.24 15.5 19.4Eleuthera Island, Bahamas
%IMP 67% -8%
GFNO25.2275.96 15.5 19.4Eleuthera Island, Bahamas
GFDL25.0176.12 14.0 10.2Eleuthera Island, Bahamas
%IMP-300% 47%
04/1000 UTC 26.6N 78.2W Grand Bahama Island, Bahamas 40.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN26.6578.63 43.0 43.1Grand Bahama Island, Bahamas
AVNO26.8877.96 35.5 39.2Grand Bahama Island, Bahamas
%IMP -50% 9%
GFNO26.7677.89 37.0 35.5Grand Bahama Island, Bahamas
GFDL26.7078.10 36.0 14.9Grand Bahama Island, Bahamas
%IMP -33% 58%
05/0430 UTC 27.2N 80.2W South end of Hutchinson Island, FL 58.5 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN27.1880.20 62.0 2.2Port St. Lucie, FL
AVNO27.8080.41 68.0 69.8Sebastian, FL
%IMP-171%-3073%
GFNO28.9780.86 73.5207.0Port Orange, FL
GFDL27.7280.38 66.0 60.4Vero Beach, FL
%IMP 50% 71%
06/1800 UTC 30.1N 84.0W Mouth of Aucilla River, FL 96.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN30.1084.00 95.0 0.0Mandalay, FL
AVNONo landfall forecast
%IMP
GFNONo landfall forecast
GFDLNo landfall forecast
%IMP

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 02 September 2004 1800 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 02 September 2004 1800 UTC.

Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 02 September 2004 1800 UTC.

Figure 4. 12-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 02 September 2004 1800 UTC.