Effects of Synoptic Surveillance on model forecasts for
15 November 1999 1800 UTC
LENNY.


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
AVNN251.328.407.519.518.547.514.463.473.654.
AVAL208.273.353.451.461.434.392.349.390.589.
%IMP17%17%13%13%11%21%24%25%18%10%
GFNO55.88.106.111.156.330.548.769.929.1135.
GFAL25.118.150.181.179.279.433.673.795.961.
%IMP55%-34%-42%-53%-15%46%21%12%14%15%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-39.-46.-69.-96.-93.-81.-45.-28.-25.-15.
AVAL-37.-44.-68.-99.-93.-81.-44.-28.-26.-17.
%IMP5%4%1%-3%0%0%2%0%-4%-13%
GFNO7.0.-10.-36.-31.-14.14.22.38.55.
GFAL6.-5.-19.-54.-38.-23.15.31.40.54.
%IMP14%und%-90%-50%-23%-64%-7%-41%-5%2%
SHNO3.-4.-23.-53.-44.-39.-6.5.7.13.
SHAL3.-4.-25.-54.-45.-38.-5.6.8.14.
%IMP0%0%-9%-2%-2%-3%17%-20%-14%-8%
DSNO3.-4.-23.-70.-61.-55.-23.-11.-10.-4.
DSAL3.-4.-25.-70.-62.-55.-22.-10.-8.-2.
%IMP0%0%-9%0%-2%0%5%9%20%50%

Landfall forecasts

17/1800 UTC 17.4N 64.8W St. Croix, USVI 48 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN18.0867.2092.0265.0 Puerto Real, PR
AVAL17.9566.4187.0181.1 Playa de Ponce, PR
%IMP15%32%
GFNO18.1365.3251.598.0 Esperanza, Vieques, PR
GFAL17.9166.2050.5158.7 Las Mareas, PR
%IMP29%-62%
18/1800 UTC 18.0N 63.3W St. Martin 72 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN19.2464.70110.0201.8 Near Anegada, British Virgin Islands
AVAL19.1464.52103.5180.4 Near Anegada, British Virgin Islands
%IMP17%11%
GFNO18.3865.0453.5188.4 Charlotte Amalie, St. Thomas, USVI
GFAL19.1664.8360.5206.3 Near Anegada, British Virgin Islands
%IMP38%-10%
19/0000 UTC 18.1N 63.1W Anguilla 78 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN Nolandfall forecast
AVAL Nolandfall forecast
%IMP
GFNO18.8364.5157.0169.3 Near Anegada, British Virgin Islands
GFAL19.1664.8360.5216.9 Near Anegada, British Virgin Islands
%IMP17%-28%
19/0600 UTC 18.0N 62.9W St. Barthelemy 84 h into the forecast
AVNN Nolandfall forecast
AVAL Nolandfall forecast
%IMP
GFNO18.8364.5157.0193.1 Near Anegada, British Virgin Islands
GFAL19.1664.8360.5240.7 Near Anegada, British Virgin Islands
%IMP13%-25%
20/0000 UTC 17.3N 61.8W Antigua 102 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN Nolandfall forecast
AVAL Nolandfall forecast
%IMP
GFNO18.8364.5157.0332.9 Near Anegada, British Virgin Islands
GFAL19.1664.8360.5380.7 Near Anegada, British Virgin Islands
%IMP8%-14%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 15 November 1999 1800 UTC (Hurricane Lenny).

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 15 November 1999 1800 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 15 November 1999 1800 UTC.

Figure 4. 12-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 15 November 1999 1800 UTC.