Effects of Synoptic Surveillance on model forecasts for
14 September 2004 0000 UTC
Ivan.


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 46 73 33 59 80130145250548813
AVNO 46 83 53 31 52114145226464725
%IMP 0%-14%-61%47%35%12% 0%10%15%11%
GFNO 54 90107 91 89 67145206131222
GFDL 63 93 83 67 67 33 96173273276
%IMP-17%-3%22%26%25%51%34%16%-108%-24%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-50-42-36-34-12 -2 1 0 3-19
AVNO-47-53-47-38-17 -6 -2 -3 5-18
%IMP 6%-26%-31%-12%-42%-200%-100%und%-67% 6%
GFNO 6 4 1-11 4 8 21 23 32 23
GFDL -5 -5 -6-10 8 5 18 17 28 4
%IMP17%-25%-500% 9%-100%38%14%26%12%83%

Landfall forecasts

16/0650 UTC 30.2N 87.9W Near Pine Beach, AL 55.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN30.3387.28 56.0 61.2Gulf Shores, AL
AVNO30.2787.59 55.0 30.8Pascagoula, MS
%IMP 100% 50%
GFNO30.2188.31 50.5 39.4Dauphin Island, AL
GFDL30.3488.14 52.0 27.8South Pass, LA
%IMP 33% 29%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 14 September 2004 0000 UTC (Hurricane Ivan).

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 2004 0000 UTC.

Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 14 September 2004 0000 UTC.

Figure 4. 14-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 14 September 2004 0000 UTC.