Effects of Synoptic Surveillance on model forecasts for
26 August 2005 0000 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
AVNN134201250241279383513542586641
AVNO102176257228230288376441496561
%IMP24%12%-3% 5%18%25%27%19%15%14%
GFNO 61170270276295346348347368285
GFDL 45166276277285327340392452432
%IMP26% 2%-2% 0% 3% 5% 2%-13%-23%-52%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-37-39-49-55-93-65-54-23-13 -2
AVNO-42-36-58-51-94-80-37-21 -9 -5
%IMP-35% 8%-18% 7%-1%-23%31% 9%31%-150%
GFNO -5 4 4 6-36-35 -1 10 -1 3
GFDL 1 0 10 15-34-35 -7 23 11 13
%IMP80%100%-150%-150% 6% 0%-600%-130%-1000-333%

Landfall forecasts

29/1110 UTC 29.3N 89.6W Near Buras, LA 83.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN 29.6185.03 78.5443.4Apalachicola, FL
AVNO30.3086.05 82.5359.8Panama City Beach, FL
%IMP 89% 19%
GFNO30.2285.94 88.0367.5Panama City, FL
GFDL30.2885.73 91.5388.7Panama City, FL
%IMP -70% -6%
29/1445 UTC 30.2N 89.6W Near LA/MS border 86.75 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN 29.6185.03 78.5445.0Apalachicola, FL
AVNO30.3086.05 82.5340.9Panama City Beach, FL
%IMP 48% 23%
GFNO30.2285.94 88.0351.4Panama City, FL
GFDL30.2885.73 91.5371.6Panama City, FL
%IMP-280% -6%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 26 August 2005 0000 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 0000 UTC.

Figure 3. NCEP Global Ensemble Prediction System track forecasts for all cyclones in the Atlantic basin initialized from 24 August 2005 0600 UTC to 25 August 2005 0000 UTC, showing the tracks of Hurricane Katrina.

Figure 4. Ensemble perturbation variance at the nominal sampling time 26 August 2005 0000 UTC from the previous day NCEP ensemble forecast. The green circles represent the dropwindsonde locations.

Figure 5. Variance explained within the verification region (large red circle) for observations taken at the sampling time 26 August 2005 0000 UTC from the Ensemble Transform Kalman Filter run from the previous day NCEP ensemble forecast. The green circles represent the dropwindsonde locations.

Figure 6. Adjoint-Derived Steering Sensitivity Vector for observations taken at the sampling time 26 August 2005 0000 UTC. The green circles represent the dropwindsonde locations.

Figure 7. NOGAPS Singular Vector for observations taken at the sampling time 26 August 2005 0000 UTC. The green circles represent the dropwindsonde locations.

Figure 8. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 26 August 2005 0000 UTC. The circles represent the dropwindsonde locations.

Figure 9. 24-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 26 August 2005 0000 UTC.