Diagnosing
the Prediction of Tropical Cyclones and their Environments in Global
Models (GFS and MPAS)
Chris
Davis
NCAR
July 31st 1:15 in room 2890
Abstract:
Tropical cyclone prediction at lead times of 5-10
days is challenging because it requires accurate prediction of
organized, deep convection across a range of scales. Related to this,
the formation and decay of tropical cyclones contribute significantly
to medium range TC prediction. This talk examines the prediction of
northern hemisphere TCs and their large-scale environments during 2012,
2013 and 2014. Results from both the Global Forecast System (GFS) and
the Model for Prediction Across Scales (MPAS) are considered. It is
shown that the GFS exhibits episodic large-scale moisture errors over
the Western Pacific Ocean that can inhibit TC formation. Regional
errors in deep convection are also shown to affect the forecast track
of TCs. In contrast, MPAS exhibits more false alarms than GFS,
especially after forecast day 7. These false alarms appear sensitive to
dissipation in the model. Despite differences between the
representation of TCs in the two models, they exhibited similar overall
track and intensity forecast skill during August and September of 2013.
Plans for MPAS development are summarized, with emphasis on
facilitating comparison with the GFS for tropical cyclone prediction.