Effects of Synoptic Surveillance on model forecasts for
06 September 2004 1800 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 49 35 81123163174 179202211361
AVNO 91 109171211300320304281262341
%IMP-86%-211% -111%-72%-84%-84%-70%-39%-24% 6%
GFNO 59 59 64125170212283290300302
GFDL 76142202224256278322314343360
%IMP-29% -141% -216%-79%-51%-31%-14%-8%-14%-19%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-66-79-94-92-113-105-98-93-108-124
AVNO-66-74-92-89-111-101 -95-90-96-113
%IMP 0% 6% 2% 3% 2% 4% 3% 3%11% 9%
GFNO 16 2 -6-12-19-12-16-10-26-37
GFDL 11 25 9 4-26-18-26-23-35-55
%IMP31%-1150%-50%67%-37% -50%-63%-130%-35%-49%

Landfall forecasts

07/2130 UTC 11.9N 61.8W 6 n mi SW of Prickly Point, Grenada 27.5 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN 12.2561.66 26.5 41.8Victoria, Grenada
AVNO12.4861.65 23.5 66.5Carriacou, Grenada
%IMP-300% -59%
GFNO12.1661.65 28.0 33.2Grenville, Grenada
GFDL13.0061.35 30.0131.6Battowie Island, St. Vincent and the Grenadines
%IMP-400%-296%
11/0330 UTC 17.4N 77.2W 20 n mi S of Portland Point, Jamaica 105.5 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN18.9376.62100.5180.7Near Oracabessa, Jamaica
AVNO17.1778.19 94.5108.1Offshore Black River, Jamaica
%IMP -120% 40%
GFNO18.9776.72 94.0181.6Near Duncans, Jamaica
GFDL19.8577.36100.5272.7Near Niquero, Granma, Cuba
%IMP 57% -50%
12/1415 UTC 18.9N 81.5W 22 n mi SSW of Georgetown, Grand Cayman Island 140.25 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNNNo landfall forecast
AVNO18.6981.67118.0 29.4Offshore Georgetown, Grand Cayman Island
%IMP
GFNONo landfall forecast
GFDLNo landfall forecast
%IMP
14/0100 UTC 21.7N 85.2W 15 n mi SW of Cabo San Antonio, Cuba 175.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNNNo landfall forecast
AVNONo landfall forecast
%IMP
GFNONo landfall forecast
GFDLNo landfall forecast
%IMP
16/0650 UTC 30.2N 87.9W Near Pine Beach, AL 228.5 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 06 September 2004 1800 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 06 September 2004 1800 UTC.

Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 06 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 06 September 2004 1800 UTC.