Extratropical transition of Western North Pacific tropical cyclones
By: Peter M. Klein
Contributors: Naval Postgraduate School (U.S.) 
Publisher: Naval Postgraduate School; Available from National Technical Information Service
Published: 1997
Place of publication: Monterey, Calif; Springfield, Va
Language: eng
Number of pages: 90
Description: Extratropical transition (ET) of a tropical cyclone (TC) often results in a mid-latitude storm that threatens      maritime and coastal interests. Cases of ET between 1 July through 31 October during 1994-1996 are      reviewed using Navy Operational Global Atmospheric Prediction System (NOGAPS) analyses and hourly      geostationary satellite imagery. Current conceptual models are found to be inadequate to explain the physical      processes in ET. ET is redefined to have two stages: transformation, where the TC is transformed from a      warm-core vortex into a baroclinic, cold-core extratropical cyclone, and re- intensification, where the      transformed TC either deepens or dissipates, depending on the existence of upper4ropospheric support for      extratropical cyclogenesis. ET is further defined in terms of two characteristic mid-latitude synoptic patterns:      meridional, in which the cyclones have meridional tracks and tend to re-intensify less vigorously than zonal,      which have zonal tracks and may deepen explosively. Review of NOGAPS 5OO-mb anomaly correlation      scores in 1996 demonstrated that ET may be associated with significant NOGAPS errors. Sea-level pressure      forecasts during ET events involving a merger tend to be too deep. In ET cases of rapidly deepening storms,      NOGAPS tends to overforecast their intensity during transformation, and then underforecast during re-      intensification. Rules of thumb are provided to assist forecasters in improving predictions of the track and      intensity of storms undergoing ET.
Notes: "September 1997."

Thesis advisor(s): Russell L. Elsberry, Patrick A. Harr.

Thesis (M.S. in Meteorology and Physical Oceanography) Naval Postgraduate School, September 1997.

Includes bibliographical references (p. 87-88)

Approved for public release; distribution unlimited.

Also available online.

Mode of access: World Wide Web.

System requirements: Adobe Acrobat reader.

US Navy (USN) author.

dk/dk cc:9116 7/10/98.