Effects of Synoptic Surveillance on model forecasts for
14 September 2004 1800 UTC
Ivan.


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 11 11 59 62 96219399648822677
AVNO 15 80122111176291515777886835
%IMP-36%-627%-107%-79%-83%-33%-29%-20%-8%-23%
GFNO 15 33 73 62170288496712900851
GFDL 22 44 83 7620635859984910331090
%IMP-47%-33%-14%-46%-21%-24%-21%-19%-15%-28%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-45-36-19 -3 -1 -2 4 -7-22-24
AVNO-37-32-25 3 2 -1 4 -7-22-23
%IMP18%11%-32% 0%-100%50% 0% 0% 0% 4%
GFNO 4 -4 -3 21 11 18 23 15 -6 -8
GFDL-10-16 -3 22 14 16 25 8-11 -2
%IMP-150%-300% 0%-5%-27%11%-9%47%-83%75%

Landfall forecasts

16/0650 UTC 30.2N 87.9W Near Pine Beach, AL 37.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN30.2587.84 38.5 8.0Gulf Shores, AL
AVNO30.2887.64 41.5 26.5Gulf Shores, AL
%IMP-200%-231%
GFNO30.4787.96 40.0 30.5Daphne, AL
GFDL30.1988.02 39.0 11.6Fort Morgan, AL
%IMP 33% 62%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 14 September 2004 1800 UTC (Hurricane Ivan).

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 14 September 2004 1800 UTC.

Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 14 September 2004 1800 UTC.

Figure 4. 14-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 14 September 2004 1800 UTC.