Effects of Synoptic Surveillance on model forecasts for
04 September 2004 0600 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 32 52112103146244 220396641731
AVNO 15 30 53 67188305375493713823
%IMP52%43% 52%45%-29%-25%-70%-24%-11%-13%
GFNO 83 83 83 78156246323507755 918
GFDL 30 45 67 972563374526519381185
%IMP65% 46% 19%-24%-64%-37%-40%-28%-24%-29%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-32-34 -8 -2 10 29 16 14 3 7
AVNO -5-23 -7 0 16 17 19 12 1 3
%IMP84%32%13%100%-60%41%-19%14%67%57%
GFNO 13 15 32 32 37 33 31 15 13 13
GFDL 12 7 22 25 43 50 37 25 13 12
%IMP 8%53%31%22%-16% -52%-19%-67% 0% 8%

Landfall forecasts

04/1000 UTC 26.6N 78.2W Grand Bahama Island, Bahamas 4.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN26.6078.36 6.5 15.9Grand Bahama Island, Bahamas
AVNO26.6278.18 3.0 3.0Grand Bahama Island, Bahamas
%IMP 60% 81%
GFNO26.3078.71 13.0 60.7Grand Bahama Island, Bahamas
GFDL26.6378.32 6.5 12.4Grand Bahama Island, Bahamas
%IMP 72% 80%
05/0430 UTC 27.2N 80.2W South end of Hutchinson Island, FL 22.5 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN 26.8980.07 26.0 36.8Jupiter, FL
AVNO26.9880.10 21.0 26.4Jupiter, FL
%IMP 57% 28%
GFNO26.5280.06 24.5 76.8Delray Beach, FL
GFDL26.7680.04 21.0 51.4Riviera Beach, FL
%IMP 25% 33%
06/1800 UTC 30.1N 84.0W Mouth of Aucilla River, FL 60.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN29.6485.43 75.0146.9Cape San Blas, FL
AVNO30.2588.08 82.5392.2Dauphin Island, AL
%IMP -50%-167%
GFNO30.3087.24 74.5311.9Pensacola, FL
GFDL30.3788.62 76.5444.5Pascagoula, MS
%IMP -14% -43%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 04 September 2004 0600 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 04 September 2004 0600 UTC.

Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 04 September 2004 0600 UTC.

Figure 4. 12-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 04 September 2004 0600 UTC.