Effects of Synoptic Surveillance on model forecasts for
21 August 2000 1200 UTC
DEBBY.


QuickTime movie of DLM wind model forecasts
QuickTime movie of DLM wind data increments


TRACK AND INTENSITY PERFORMANCE

TRACK (km)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN63.101.123.91.143.
AVAL85.182.252.253.200.
%IMP-35%-80%-105%-148%-178%
GFNO40.111.128.115.323.606.
GFAL40.100.103.107.292.548.
%IMP0%10%20%7%10%10%
VBNO78.98.107.147.321.569.
VBAL78.96.128.168.351.621.
%IMP0%2%-20%-14%-9%-9%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-31.-32.-35.-31.-8.
AVAL-30.-32.-34.-34.-20.
%IMP3%0%3%-10%-150%
GFNO-17.5.25.40.59.72.
GFAL-21.6.19.31.61.77.
%IMP-24%-20%24%23%-3%-7%
SHNO-24.-19.-21.-15.9.22.
SHAL-25.-22.-26.-22.0.12.
%IMP-4%-16%-24%-47%100%45%
DSNO-24.-19.-26.-27.-11.-3.
DSAL-25.-22.-30.-29.-12.-3.
%IMP-4%-16%-15%-7%-9%0%

Landfall forecasts

22/0600 UTC 17.5N 61.7W near Barbuda 18 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN16.8961.9216.071.7 Old Road, Antigua
AVAL17.9361.7914.548.7 Near Barbuda
%IMP-75%32%
GFNO16.6861.4416.095.2 Near Guadeloupe
GFAL16.7061.3816.095.2 Near Guadeloupe
%IMP0%0%
VBNO17.6661.7921.020.2 Codrington,Barbuda
VBAL17.7661.8221.031.6 Codrington, Barbuda
%IMP0%-56%
22/0915 UTC 17.9N 62.8W near St.-Barthelemy 22.25 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN17.0962.5518.093.8 Red Cliff, Nevis
AVAL17.0562.6717.095.4 Dogwood Point, Nevis
%IMP-24%-2%
GFNO16.8262.2519.0133.4 Plymouth, Montserrat
GFAL16.8662.1519.0134.5 Plymouth, Montserrat
%IMP0%-1%
VBNO18.0863.1426.041.1 Marigot, St. Martin
VBAL18.1663.1126.043.7 Marigot, St. Martin
%IMP0%-6%
22/1500 UTC 18.5N 64.4W near Virgin Gorda 27 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN17.7064.7025.594.4 Vagthus Point, St. Croix, U.S. Virgin Islands
AVAL17.3065.0024.0147.6 Near St. Croix, U.S. Virgin Islands
%IMP-20%-56%
GFNO17.6164.9430.5114.2 Sandy Point, St. Croix, U.S. Virgin Islands
GFAL17.7764.8330.092.9 Davis Beach, St. Croix, U.S. Virgin Islands
%IMP14%19%
VBNO18.5964.5831.521.4 Near Tortola, British Virgin Islands
VBAL18.6264.4531.514.3 Anegada
%IMP0%33%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 21 August 2000 1200 UTC (Hurricane Debby).

Figure 2. Track forecasts for the no dropwindsonde (NO or NN) and the all dropwindsonde (AL) runs for the AVN, GFDL, and VBAR models initialized on 21 August 2000 1200 UTC. The best track is shown in black.

Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 21 August 2000 1200 UTC.

Figure 4. 12-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 21 August 2000 1200 UTC.