A new approach in the study of Cut-off lows (COLs) in South America

MARIA G. NICORA; RENE GARREAUD; ELIAN WOLFRAM; RODRIGO E. BÜRGESSER; ELDO E AVILA

Santiago de Chile

Conferencia; International Conference on Souther Hemisphere Meteorology and Oceography; 1015

facultad de ciencias fisicas y matematicas

Cut-off lows (COLs) are upper-level, low pressure centers that segregate from the main westerly flow at midlatitudes and subsequently moves over the subtropics. Over South America, several studies have documented the potential of COLs to produce significant weather, including heavy snowfall ,rainfall and strong winds. In this work we use a new approach to study of COLs in South America, based on their attending lighting activity, and the possibility of use that data as a proxy of the COL severe weather. On the basis three years (2013-1015) of stroke data from the Word Wide Lightning Location Network, we describe the lightning activity associated with selected COLs in our target region. The activity often begin in the first stage of the COL formation, associated with the core of the cold air on the western side of the continent, and several times this activity continues as the COL enters in its mature phase as it moves over the continent. Because the lightning activity in a thunderstorm is related to the kinetic energy of the thunderstorm updraft, the study of this activity may shed light on the environment of the COL that can be conducive to mixed-phase microphysical processes, associated charge transfer microphysics and cloud-scale separation of charge centers.We also noted that some COLs produce little precipitation and yet they are accompanied by significant lightning activity. Such combination may lead to forest fires over the Patagonian Andean Forests, especially during the dry, summer season. Thus, identification of COLs and lightning in the first stages could be used like as a possible indicator to the ignition potential.