The Extratropical Transition of Tropical Cyclones. Part II: Interaction with the Midlatitude Flow, Downstream Impacts, and Implications for Predictability

Download
Author
Keller, Julia H.
Grams, Christian M.
Riemer, Michael
Archambault, Heather M.
Bosart, Lance
Doyle, James D.
Evans, Jenni L.
Galarneau, Thomas J.JR.
Griffin, Kyle
Harr, Patrick A.
Kitabatake, Naoko
McTaggart-Cowan, Ron
Pantillon, Florian
Quinting, Julian F.
Reynolds, Carolyn A.
Ritchie, Elizabeth A.
Torn, Ryan D.
Zhang, FuQing
Date
2019-04Metadata
Show full item recordAbstract
The extratropical transition (ET) of tropical cyclones often has an important impact on the nature and predictability
of the midlatitude flow. This review synthesizes the current understanding of the dynamical and physical
processes that govern this impact and highlights the relationship of downstream development during ET to highimpact
weather, with a focus on downstreamregions. It updates a previous review from2003 and identifies new and
emerging challenges and future research needs. First, the mechanisms through which the transitioning cyclone impacts
the midlatitude flow in its immediate vicinity are discussed. This ‘‘direct impact’’manifests in the formation of a
jet streak and the amplification of a ridge directly downstream of the cyclone. This initial flow modification triggers or
amplifies amidlatitude Rossby wave packet,which disperses the impact ofETinto downstream regions (downstream
impact) and may contribute to the formation of high-impact weather. Details are provided concerning the impact of
ET on forecast uncertainty in downstream regions and on the impact of observations on forecast skill. The sources
and characteristics of the following key features and processes thatmay determine the manifestation of the impact of
ET on the midlatitude flow are discussed: the upper-tropospheric divergent outflow, mainly associated with latent
heat release in the troposphere below, and the phasing between the transitioning cyclone and the midlatitude wave
pattern. Improving the representation of diabatic processes during ET in models and a climatological assessment of
the ET’s impact on downstream high-impact weather are examples for future research directions.
Description
The article of record as published may be found at http://dx.doi.org/10.1175/MWR-D-17-0329.1
This review was partly initiated at the
World Meteorological Organization’s Eighth International
Workshop on Tropical Cyclones in 2014.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.Collections
Related items
Showing items related by title, author, creator and subject.
-
Downstream Development Associated with the Extratropical Transition of Tropical Cyclones over the Western North Pacific
Harr, Patrick A.; Dea, Jonathon M. (2009);The movement of a tropical cyclone into the midlatitudes involves interactions among many complex physical processes over a variety of space and time scales. Furthermore, the extratropical transition (ET) of a tropical ... -
An eddy kinetic energy view of physical and dynamical processes in distinct forecast scenarios for the extratropical transition of two tropical cyclones
Keller, Julia H.; Jones, Sarah C.; Harr, Patrick A. (American Meteorological Society, 2014-08);The extratropical transition (ET) of Hurricane Hanna (2008) and Typhoon Choi-Wan (2009) caused a variety of forecast scenarios in the European Centre for Medium-Range Weather Forecasts (ECMWF) Ensemble Prediction System ... -
Sensitivity experiments for ensemble forecasts of the extratropical transition of typhoon Tokage (2004)
Anwender, Doris; Jones, Sarah C.; Leutbecher, Martin; Harr, Patrick A. (2010-01);The extratropical transition (ET) of tropical cyclones often has a detrimental impact on predictability in the vicinity of the event and downstream. Ensemble forecasts provide an appropriatemeans by which to investigate ...