Effects of Synoptic Surveillance on model forecasts for
07 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 90109168209286305 284196267335
AVNO 55 95140186209178175129250315
%IMP39%13% 17%11%27%42%38%34% 6% 6%
GFNO 39133214272311369368389489546
GFDL 33165226289312359347377500566
%IMP15% -24% -6%-6%-0% 3% 6% 3%-2%-4%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-73-87-95-99-114-106-98-112-97-120
AVNO-58-70-76-84-98-90 -82-92-81-104
%IMP21%20%20%15%14%15%17%18%16%13%
GFNO 13 7 12 -2-21-26-31-43-40-65
GFDL 7 9 10 -6-24-31-32-40-42-64
%IMP46%-29%17%-200%-14% -19%-3% 7%-5% 2%

Landfall forecasts

07/2130 UTC 11.9N 61.8W 6 n mi SW of Prickly Point, Grenada 21.5 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN 11.7261.91 18.0 23.3Near St. George's, Grenada
AVNO12.3561.57 18.5 55.9Victoria, Grenada
%IMP 14%-140%
GFNO12.5661.36 23.0 87.5Petite Martinique, Grenada
GFDL13.0061.33 22.5132.4Kingstown, St. Vincent, St. Vincent and the Grenadines
%IMP 33% -51%
11/0330 UTC 17.4N 77.2W 20 n mi S of Portland Point, Jamaica 99.5 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN17.7877.95 93.5 90.0Near Rowes Corner, Jamaica
AVNO18.4076.10 96.0160.8Near Boston Bay, Jamaica
%IMP 42% -79%
GFNO19.8975.53 88.0327.8Santiago de Cuba, Santiago de Cuba, Cuba
GFDL19.9375.81 90.0316.8Santiago de Cuba, Santiago de Cuba, Cuba
%IMP 17% 3%
12/1415 UTC 18.9N 81.5W 22 n mi SSW of Georgetown, Grand Cayman Island 134.25 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN19.7880.83111.5120.4Near Georgetown, Grand Cayman Island
AVNONo landfall forecast
%IMP
GFNONo landfall forecast
GFDLNo landfall forecast
%IMP
14/0100 UTC 21.7N 85.2W 15 n mi SW of Cabo San Antonio, Cuba 169.0 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 222.5 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 07 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 07 September 2004 0000 UTC.

Figure 3. NCEP Global Ensemble Predction System track forecasts for all cyclones in the Atlantic basin initialized from 05 september 2004 0600 UTC to 06 September 2004 0000 UTC, showing the tracks of Hurricane Ivan.

Figure 4. Ensemble perturbation variance at the nominal sampling time 07 September 2004 0000 UTC from the previous day NCEP ensemble forecast. The green circles represent the dropwindsonde locations.

Figure 5. Variance explained within the verification region (large red circle) for observations taken at the sampling time 07 September 2004 0000 UTC from the Ensemble Transform Kalman Filter run from the previous day NCEP ensemble forecast. The green circles represent the dropwindsonde locations.

Figure 6. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 07 September 2004 0000 UTC. The circles represent the dropwindsonde locations.

Figure 7. 24-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 07 September 2004 0000 UTC.