Effects of Synoptic Surveillance on model forecasts for
14 September 2003 1800 UTC
Isabel.


Quicktime movie of GFS 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 24 20 52 77156226290315374522
AVNO 30 30 37 53107111122170219301
%IMP-25%-50%19%31%31%51%58%46%41%42%
GFNO 30 73 89126155229354409435398
GFDL 15 56 67 91 91134211270266254
%IMP50%23%25%28%28%41%40%34%39%36%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-82-69-50-45-42-36-38-21 13 11
AVNO-59-43-26-19-16-13-10 -8 11 4
%IMP20%38%48%58%62%64%78%62%15%64%
GFNO -5-12 -2 6 3 2 1 -6 14 24
GFDL-18-16 -6 -1 -1 8 8 1 13 23
%IMP-260%-33%-200%83% 33%-300%-700%83% 7% 4%
SHNO 6 17 30 31 21 15 1 -8 15 29
SHIP 3 12 25 23 12 7 -7-14 10 25
%IMP50%29%17%26%43%53%-600%-75%33%14%
DSNO 6 17 30 31 21 15 1-22-12 0
DSHP 3 12 25 23 12 7 -7-30-14 0
%IMP50%29%17%26%43%53%-600%-36%-17% 0%

Landfall forecasts

18/1700 UTC 34.9N 76.2W Drum Inlet, NC 95.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN35.2475.62105.0 64.9Hatteras, NC
AVNO37.1475.99105.0249.6Kiptopeke, VA
%IMP 0%-285%
GFNO36.6175.88 88.0191.2Campbells Landing, VA
GFDL37.3775.83 95.5268.6Broadwater, VA
%IMP 93% -41%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 14 September 2003 1800 UTC (Hurricane Isabel).

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 2003 1800 UTC.

Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 14 September 2003 1800 UTC.

Figure 4. 12-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 14 September 2003 1800 UTC.