U.S.-ITALY Research Workshop on the
Hydrometeorology, Impacts,and Management of Extreme Flood
Perugia; Italy, Nov. 13-17, 1995
Meteorological and Climatic Factors Affecting Extreme Floods: Prospects for Mesoscale Model Prediction and Satellite Precipitation Monitoring of Terrain-forced Events
Eric A. SMITH
Department of Meteorology,
Florida State University,
Tallahassee, FL 32306,U.S.A.
Phone: +904-644.4253 - Fax: +904-644.9639
Alberto MUGNAI
Istituto di Fisica dell'Atmosfera,
Consiglio Nazionale delle Ricerche,
Via Galileo Galilei, 00044 Frascati, Italy
Phone: +39-6-941.86215 - Fax: +39-6-941.86266
Gregory J. TRIPOLI
Department of Atmospheric and Ocean Sciences,
University of Wisconsin,
Madison, WI 53706, U.S.A.
Phone: +608-262.3700 - Fax: +608-262.0166
This study examines various meteorological and climatic factors leading
up to various major damaging floods that have occurred in the continental
United States in the last few decades, with a view toward explaining why
a combination of mesoscale modeling and satellite-based precipitation monitoring
may be the only realistic approach in obtaining timely inputs to a hydrological
flood forecast model. The premise of this study is that a flood producing
storm is a complex but understandable meteorological extreme, whose genesis
conditions are only predictable with a mesoscale model because of the intricate
synoptic scale-mesoscale interactions, but whose specific location, precipitation
efficiency, and total rain production are best left to a real-time, geosynchronous
satellite-based infrared rainfall monitoring algorithm, periodically calibrated
by a passive microwave-based rain-profile algorithm. The study focuses
on arguments concerning why such an approach is warranted, particularly
in the context of the mountain areas of northern Italy, where terrain features
serve to organize and focus storm development as an outgrowth from synoptic
scale conditions favorable to storm occurrence. An example of applying
a mesoscale model and satellite rainfall analysis to an extreme flood event
that took place in the Genova area in late September, 1992, is presented.
The pursuant analysis is designed to help develop the main themes of our
argument that the main features of a flood producing storm occurring in
mountain terrain can be predicted with such a model, while the specific
precipitation features are identifiable and quantifiable from a combination
of time-sequenced infrared and less frequent SSM/I images obtained from
METEOSAT and DMSP satellites, respectively.