Effects of Synoptic Surveillance on model forecasts for
26 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 78146126 67 32 66189247400
AVNO 94156102 67 24 59123162237
%IMP-21%-7%19% 0%25%11%35%34%41%
GFNO 54146156153 94 11159238338
GFDL 73194187150119 87128122150
%IMP-35%-33%-20% 2%-27%-861%19%49%56%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-38-44-46-85-74-37-12 -8-13
AVNO-36-52-40-80-69-37-13 -8-10
%IMP 5%-18%13% 6% 7% 0%-8% 0%23%
GFNO 7 5 15-26-17 7 17 -5 -5
GFDL 6 10 20-28-29 -3 26 -6 -4
%IMP14%-100%-33%-8%-70%57%-53%-20%20%

Landfall forecasts

29/1110 UTC 29.3N 89.6W Near Buras, LA 71.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN 29.2890.14 73.0 52.4Grand Isle, LA
AVNO29.4990.14 73.5 56.4Grand Isle, LA
%IMP -25% -8%
GFNO28.9789.42 67.5 40.6South Pass, LA
GFDL29.9688.76 75.0109.3Chandeleur Islands, LA
%IMP -14%-169%
29/1445 UTC 30.2N 89.6W Near LA/MS border 74.75 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN 29.2890.14 73.0114.7Grand Isle, LA
AVNO29.4990.14 73.5 94.5Grand Isle, LA
%IMP 29% 19%
GFNO30.2189.74 76.5 13.5Slidell, LA
GFDL30.3588.78 77.5 80.4Biloxi, MS
%IMP -57%-496%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 26 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 26 August 2005 1200 UTC.

Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 26 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 26 August 2005 1200 UTC.