Effects of Synoptic Surveillance on model forecasts for
08 September 2004 0600 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 74 78 74 70110182214293403462
AVNO 11 34 89 85179258275344532728
%IMP85%56%-20%-21%-63%-42%-29%-17%-32%-58%
GFNO 62164224317339376435555704907
GFDL 35102140203212231305398443492
%IMP44% 38% 37%36%37%39%30%28%37%56%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-81-102-93-84-83-81-101-92-90-100
AVNO-63-93-78-77-71-72-79-78-88-94
%IMP22% 9%16% 8%14%11%22%15% 2% 6%
GFNO -9-17 -4-11-24-42-58-48-40-43
GFDL 3 -8 -3 1 -1-20-28-24-35-42
%IMP67%53%25%91%96% 52%52%50%12% 2%

Landfall forecasts

11/0330 UTC 17.4N 77.2W 20 n mi S of Portland Point, Jamaica 69.5 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN 18.2176.32 75.0129.5Boston Bay, Jamaica
AVNO17.9176.21 82.0119.1Golden Grove, Jamaica
%IMP-127% 8%
GFNO18.1272.78 45.0474.5Jacmel, Haiti
GFDL18.1976.35 57.0125.7Boston Bay, Jamaica
%IMP 49% 74%
12/1415 UTC 18.9N 81.5W 22 n mi SSW of Georgetown, Grand Cayman Island 104.25 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN 19.6877.93 94.0384.3Near Niquero, Granma, Cuba
AVNO20.0777.51100.0437.6Niquero, Granma, Cuba
%IMP 59% -14%
GFNO19.8875.35 61.0653.6Guantanamo Bay, Cuba
GFDL21.5081.62 94.0289.1Cayo Largo, Cuba
%IMP 76% 56%
14/0100 UTC 21.7N 85.2W 15 n mi SW of Cabo San Antonio, Cuba 139.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN 21.5579.29107.0612.7Sancti Spiritus, Sancti Spiritus, Cuba
AVNO20.0777.51100.0818.5Niquero, Granma, Cuba
%IMP 7% -34%
GFNO19.8875.35 61.01042.9Guantanamo Bay, Cuba
GFDL22.5483.01104.5244.0Los Palacios, Pinar del Rio, Cuba
%IMP 56% 77%
16/0650 UTC 30.2N 87.9W Near Pine Beach, AL 198.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNNNo landfall forecast
AVNONo landfall forecast
%IMP
GFNONo landfall forecast
GFDLNo landfall forecast
%IMP

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 08 September 2004 0600 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 08 September 2004 0600 UTC.

Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 08 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 08 September 2004 0600 UTC.