U.S.-
Italy Research Workshop on the
Hydrometeorology, Impacts, and Management of Extreme
Floods
Perugia
(Italy), November 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.
Alberto Mugnai
Istituto di Fisica dell'Atmosfera,
Consiglio Nazionale delle Ricerche,
Via Galileo Galilei, 00044 Frascati, Italy
Gregory J. Tripoli
Department of Atmospheric and Ocean Sciences,
University of Wisconsin,
Madison, WI 53706, U.S.A.
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.