Effects of Synoptic Surveillance on model forecasts for
12 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 0 73 53 61 96164226288324244
AVNO105150105141166249278384354163
%IMPund%-105%-98%-131%-73%-52%-23%-33%-9%33%
GFNO 10 35 51 46 52 24 15 44171295
GFDL 69134111158166213203263248119
%IMP-590%-283%-118%-243%-219%-788%-1253%-498%-45%60%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-67-59-69-40-40-41-22 2 12 2
AVNO-61-65-67-44-35-37-44-12 7 2
%IMP 9%-10% 3%-10%12%10%-100%-050%42% 0%
GFNO-13 -8-21 0 -6 -8 -5 17 21 20
GFDL-16-14-21 -6-18-19-27 -9 17 24
%IMP-23%-75% 0%und%-200%-138%440%47%10%-20%

Landfall forecasts

14/0100 UTC 21.7N 85.2W 15 n mi SW of Cabo San Antonio, Cuba 31.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN 21.7684.51 29.5 71.5Near La Fe, Pinar del Rio, Cuba
AVNO21.9584.07 21.5119.8La Fe, Pinar del Rio, Cuba
%IMP-533% -68%
GFNO21.5585.20 27.5 16.7Near La Fe, Pinar del Rio, Cuba
GFDL21.8484.37 22.0 87.0Near La Fe, Pinar del Rio, Cuba
%IMP-157%-421%
16/0650 UTC 30.2N 87.9W Near Pine Beach, AL 85.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN30.1085.49 91.0231.8Panama City, FL
AVNO29.6685.26 80.0261.2Indian Pass, FL
%IMP 17% -13%
GFNO30.3887.84 85.0 20.8Gulf Shores, AL
GFDL30.4686.58 78.0129.8Fort Walton Beach, FL
%IMP und%-524%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 12 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 12 September 2004 1800 UTC.

Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 12 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 12 September 2004 1800 UTC.