Objective and Automated Assessment of Operational Global Forecast Model

Predictions of Tropical Cyclone FormationPatrick A. Harr

Naval Postgraduate SchoolMonterey, CA

Acknowledgment: Joint Hurricane Testbed Project

•Synthesize model representations of 850 hPa vorticity centers

•Summarize a large number of parameters associated with

each center throughout its life cycle.

•Catalog in a dynamic data base to allow - summaries of current vortices- summaries of past vortices based on common factors (i.e., season, location, developing, non-developing, etc.)

Identify factors that discriminate between likely modeltraits with respect to tropical cyclone formation.

[ Objective, feature based, dynamic]

OBJECTIVES

Forecast Model Analyses and Forecast FieldsForecast Model Analyses and Forecast Fields

Tropical CycloneVortex TrackingProgram(TCVTP)

Tropical CycloneVortex TrackingProgram(TCVTP)

Forecast Data BaseCirculations forecast to

occur

Forecast Data BaseCirculations forecast to

occur

Analyzed Data BaseCurrent tropical

circulations

Analyzed Data BaseCurrent tropical

circulations

Current circulation summaries/ verifications

Current circulation summaries/ verifications

Final Circulation Catalogsummaries/verifications

Final Circulation Catalogsummaries/verifications

Catalog of False Alarms

Catalog of False Alarms

With respect to the ellipse representation ofeach tracked vortex, the following parameters are cataloged:

850 maximum valueSLP average, minimum value500-850 hPa shear 10ox10o box excluding the

200-850 hPa shear ellipse

1000-200 height thickness500 hPa vertical motion700-500 hPa moisturemodel-derived accumulated precipitationtemperature difference between area inside

ellipse and outside ellipse at 200 hPa

Summaries at 2003082500 GFS

Summaries at 2003082712 GFS

Summaries at 2003082500 NOGAPS

Summaries at 2003082712 NOGAPS

Summaries at 2003083000

NOGAPS

Aug-Oct Atlantic Numbered Vortices (Erika – Nicholas)

Eastern Atlantic (East of 30oW) Non-developing Vortices – duration > 24 h

Objectively identify and track analyzed and forecast vorticity centers in operational global forecast models

Summarize a comprehensive set of physical parameters associated with analyzed and forecast vortices.

Catalog parameters in a dynamic data base

Provide daily and other summaries of model forecast performance associated with developingand non-developing tropical vortices.

Use summaries to discriminate between potentiallyaccurate/inaccurate forecasts of TC formation.