Effects of Synoptic Surveillance on model forecasts for
18 September 2002 0000 UTC
Isidore.


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
AVNN15.94.62.46.61.15.85.62.21.53.
AVNO67.54.22.43.69.53.84.83.89.73.
%IMP-347%43%65%7%-13%-253%1%-34%-324%-38%
GFNO84.176.148.177.301.418.431.488.406.368.
GFAL33.87.133.94.106.171.215.217.261.460.
%IMP61%51%10%47%65%59%50%56%36%-25%
AVNN-20.-26.-34.-52.-61.-54.-76.-90.-89.-81.
AVNO-14.-23.-30.-46.-56.-47.-72.-85.-85.-76.
%IMP30%12%12%12%8%13%5%6%4%6%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
GFNO-8.-16.-19.-20.-20.-1.-4.-19.0.21.
GFAL-1.19.38.23.18.41.18.3.1.6.
%IMP87%-19%-100%-15%10%-4000%-350%84%und%77%
SHNO-4.-5.-5.-11.-12.5.-17.-27.-28.-20.
SHIP-4.-5.-6.-11.-13.3.-19.-29.-29.-22.
%IMP0%0%-20%0%-8%40%-12%-7%-4%-10%
DSNO-4.-5.-5.-11.-24.-8.-30.-40.-40.-54.
DSHP-4.-5.-6.-11.-25.-8.-30.-40.-41.-54.
%IMP0%0%-20%0%-4%0%0%0%-3%0%

Landfall forecasts

20/2100 UTC 22.0N 84.1W Cabo Frances, Cuba 69 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN21.3983.1753.0117.5 Punta de Guanal, La Isla de la Juventud, Cuba
AVAL21.4482.9054.0138.6 Punta de Guanal, La Isla de la Juventud, Cuba
%IMP6%-18%
GFNO
GFAL21.9984.0158.09.3 Cabo Frances, Pinar del Rio, Cuba
%IMP
22/2100 UTC 21.3N 89.3W Puerto Telchac, Yucatan, Mexico 117 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN21.2889.78118.549.7 Progreso, Yucatan, Mexico
AVAL21.1990.03117.576.6 Sisal, Yucatan, Mexico
%IMP33%-54%
GFNO21.2385.1954.0425.6 Near Cancun, Yucatan, Mexico
GFAL24.0087.0096.0381.6 North of Yucatan, Peninsula
%IMP67%10%
26/0600 UTC 29.1N 90.3W Just west of Grand Isle, LA 198 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN No landfall forecast
AVAL No landfall forecast
%IMP
GFNO No landfall forecast
GFAL No landfall forecast
%IMP

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 18 September 2002 0000 UTC (Tropical Depression Ten).

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 18 September 2002 0000 UTC. The best track is shown in black.

Figure 3. Ensemble perturbation variance at the nominal sampling time 18 September 2002 0000 UTC from the previous day NCEP ensemble forecast. The triangles represent the dropwindsonde locations.

Figure 4. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 18 September 2002 0000 UTC. The triangles represent the dropwindsonde locations.

Figure 5. 12-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 18 September 2002 0000 UTC.