Effects of Synoptic Surveillance on model forecasts for
10 September 2004 1200 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 88139200238322412512573783881
AVNO 25 85 94138214341500606802918
%IMP72%59%43%42%34%17% 2%-6%-2%-4%
GFNO 24 85111183266357499565694741
GFDL 33 42105175247343484547701738
%IMP-38%51% 5% 4% 7% 4% 3% 3%-1% 0%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-75-79-91-78-76-89-86-90-63-65
AVNO-60-66-90-75-65-88-80-84-67-66
%IMP20%16% 1% 4%14% 1% 7% 7%-6%-1%
GFNO -7 -6-30-23-10-29-37-48-39-34
GFDL-11-11-31-17-12-29-33-43-37-44
%IMP-57%-83%-3%26%-20% 0%11%10% 5%-29%

Landfall forecasts

11/0330 UTC 17.4N 77.2W 20 n mi S of Portland Point, Jamaica 15.5 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN 17.8676.35 23.5103.5Morant Bay, Jamaica
AVNO17.8876.93 22.5 60.5Kingston, Jamaica
%IMP 13% 42%
GFNO17.6777.25 28.5 30.5Salt River, Jamaica
GFDL17.8377.67 30.0 69.0Alligator Pond, Jamaica
%IMP -12%-126%
12/1415 UTC 18.9N 81.5W 22 n mi SSW of Georgetown, Grand Cayman Island 50.25 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN 20.9279.68 61.0294.1Near Cayo Breton, Cuba
AVNO19.9880.25 57.0177.6Near Cayman Brac
%IMP 37% 40%
GFNO20.4780.07 55.0229.8Near Cayo Breton, Cuba
GFDL20.3580.15 55.5214.3Near Cayman Brac
%IMP -11% 7%
14/0100 UTC 21.7N 85.2W 15 n mi SW of Cabo San Antonio, Cuba 85.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN 21.8580.19 70.0517.2Trinidad, Sancti Spiritus, Cuba
AVNO22.1081.20 72.0414.7Near Cienfuegos, Cienfuegos, Cuba
%IMP 13% 20%
GFNO22.1881.55 68.5379.9Near Jaguey Grande, Matanzas, Cuba
GFDL21.7181.33 66.5399.5Cayo Largo, Cuba
%IMP -12% -5%
16/0650 UTC 30.2N 87.9W Near Pine Beach, AL 139.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN25.1281.07 94.0877.6Flamingo, FL
AVNO25.6881.28 93.5821.2Chokoloskee, FL
%IMP -1% 6%
GFNO28.2182.75104.0546.2Beacon Square, FL
GFDL28.7082.51107.0547.4Spring Hill, FL
%IMP 9% 0%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 10 September 2004 1200 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 10 September 2004 1200 UTC.

Figure 3. NCEP Global Ensemble Predction System track forecasts for all cyclones in the Atlantic basin initialized from 08 September 2004 1800 UTC to 09 September 2004 1200 UTC, showing the tracks of Hurricane Ivan.

Figure 4. Ensemble perturbation variance at the nominal sampling time 10 September 2004 1200 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 10 September 2004 1200 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 10 September 2004 1200 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 10 September 2004 1200 UTC.