Nevadas en el Sudeste Bonaerense: climatología sinóptica y un caso de estudio

this paper presents a statistic of the frequency of snow-fall occurred over the southeast of buenos aires province over a 35 year period (1960-2004). considering present weather information 32 events were found and only 7 events show snow over more than one synoptic station. a synoptic climatology of the cold air incursions that are responsible for snow-fall in the study region is shown in order to understand the circulation patterns. atmospheric circulation patterns are characterized by extreme anomalies linked to the trough associated to cold front and the ridge in post-frontal areas that denote the intensity of these systems,. the anomalies field of geopotencial height shows a negative extreme over the frontal trough in the cases of generalized snow duplicate the intensity in cases with isolated snow. the intense cyclonic regime favors the convergence at low levels and the strong cooling, evident in the anomalies of temperature at mid-levels, indicating the instability generated in the air mass that is lead towards the northern patagonian coast and the argentinean sea. a case study of a generalized snow-fall related to a strong cold air incursion occurred on 10 july 2004 over the southeast coast of the buenos aires province. the synoptic situation is analyzed in relation to the long period sample and the polar air mass evolution is characterized using rams model in a diagnostic mode. the snow-fall is related to a persistent destabilization favored by heating and moisturizing in a prevalently maritime trajectory and by convergence in a cyclonic regime.