Linkage between regional weather systems and hydrologic cycles over Central America

Central America is a narrow section of land that connect North America and South America and divide Pacific Ocean form Atlantic Ocean. This characteristic makes the climatology over Central America complex. One of this complex situation can be observed on the bimodal precipitation pattern that develops annually on Central America. This phenomena is known as mid-summer drought (MSD), it is the reduction of the precipitation amount during the rainy season (May to November). This study concentrated on the correlation that large scale climate phenomena (El Niño Southeastern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), Atlantic Multidecadal Oscillation (AMO) and North Atlantic Oscillation (NAO)), tropical cyclones (TC), extra tropical cyclones (ExTC) and other weather systems, have on the interannual precipitation variability over Central America. Results shows a strong negative correlation coefficient between the precipitation attributed to tropical cyclones, total rain and CP index (around 0.6), on the correlation between PDO index and rain attributed to others and total rain; we found a strong negative correlation (around 0.65); both of this maximum correlation coefficient were obtained with a Lag of five to six months, index leading (advancing), precipitation lagging (delaying), on the Pacific side of Central America. In others words, a high (low) PDO or CP now, might cause the decrease of the precipitation attributed to tropical cyclones and total precipitation to decrease (increase) five to six months from now, mostly along the Pacific side of Central America.