In particular, the NCEP Global Forecast System (GFS) showed a large shift in its track forecast of Joaquin with the 0000 UTC cycle on 1 October, moving Joaquin over Long Island and southeastern New England, as compared to previous cycles that showed Joaquin making landfall in the Carolinas. This model cycle also marked the assimilation of numerous dropwindsonde observations from a synoptic surveillance mission flown around Joaquin by the NOAA Gulfstream-IV jet. Subsequent model runs after the 00Z cycle on 1 October continued an eastward shift in the track, and ultimately Joaquin remained well offshore of the U.S. East Coast.
Previous research has shown impacts in several cases from these supplemental dropwindsondes on the track, intensity, and structure of tropical cyclones. Here, the results from a data denial study using the NCEP GSI/GFS system will be presented to examine the impact of the G-IV dropwindsondes on the track, intensity, and structure of Joaquin, with a particular focus on the 0000 UTC cycle on 1 October.