Effects of Synoptic Surveillance on model forecasts for
15 September 2003 1200 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 40 76168275329357497839
AVNO 39 35 50106149143204316439
%IMP-63%12%34%37%36%57%43%36%48%
GFNO 49 67 78 80111170 96102190
GFDL 70 89 91 89104166105 40290
%IMP-43%-33%-17%-11% 6% 2%19%61%-53%
INTENSITY (kt)
MODEL12 h24 h36 h48 h60 h72 h84 h96 h108 h120 h
AVNN-56-45-39-37-33-31 3 19 4
AVNO-28-24-21-15-13-18 13 8 6
%IMP50%47%46%41%59%42%-333%58%-50%
GFNO -2 3 1 1 6 3 4 29 34
GFDL 6 2 8 3 8 0 2 26 35
%IMP-200%33%-700%-200%-33%100%59%10%-3%
SHNO 8 17 16 17 8 -4 6 25 27
SHIP 9 19 18 14 3-12 -3 17 24
%IMP-13%-12%-13%18%62%-200%50%32%11%
DSNO 8 17 16 17 8 -4-17 -1 4
DSHP 9 19 18 14 3-12-21 -3 3
%IMP-13%-12%-13%18%62%-200%-24%-200%25%

Landfall forecasts

18/1700 UTC 34.9N 76.2W Drum Inlet, NC 77.0 h into the forecast
MODELLATLONTIMEERRORLOCATION
AVNN36.5075.87 91.5180.2Knotts Island, NC
AVNO35.4076.10 84.0 56.3Cape Lookout, NC
%IMP 52% 69%
GFNO35.2075.60 72.0 63.9Hatteras, NC
GFDL35.0076.10 72.0 14.4Ocracoke, NC
%IMP 0% 77%

Figure 1. NCEP 850 - 200 hPa mean wind analysis for 15 September 2003 1200 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 15 September 2003 1200 UTC.

Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 15 September 2003 1200 UTC.

Figure 4. 12-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 15 September 2003 1200 UTC.