Effects of Synoptic Surveillance on model forecasts for
27 August 2005 1200 UTC
Katrina.

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 39 87 90140256338367
AVNO 52 67 77112187240275
%IMP-33%23%14%20%27%29%25%
GFNO 52 46 45 59209345500
GFDL 32 83 68 68165262428
%IMP38%-80%-58%-15%21%24%14%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-45-91-77-36 3 -4-12
AVNO-21-61-47-15 -5 -6-13
%IMP53%33%39%58%-67%-50%-8%
GFNO 0-25-13 14 26 -7 -6
GFDL 1-26-14 4 18 -8 -6
%IMPund%-4%-8%71%31%-14% 0%

Landfall forecasts
29/1110 UTC 29.3N 89.6W Near Buras, LA 47.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN 29.2090.85 50.5121.7Cocodrie, LA
AVNO29.1290.69 47.5107.6Cocodrie, LA
%IMP 86% 12%
GFNO29.4890.23 48.5 64.2Grand Isle, LA
GFDL29.0990.17 45.0 60.2Grand Isle, LA
%IMP -33% 6%
29/1445 UTC 30.2N 89.6W Near LA/MS border 50.75 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN 29.2090.85 50.5121.7Cocodrie, LA
AVNO29.1290.69 47.5107.6Cocodrie, LA
%IMP-1000% 12%
GFNO29.4890.23 48.5100.4Grand Isle, LA
GFDL29.0990.17 45.0135.0Grand Isle, LA
%IMP-156% -34%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 27 August 2005 1200 UTC (Hurricane Katrina).

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 27 August 2005 1200 UTC.

Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 27 August 2005 1200 UTC.

Figure 4. 12-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 27 August 2005 1200 UTC.