Southeastern Pacific blocking episodes are studied using 17 years of reanal
yzed daily data from the National Centers for Environmental Prediction (NCE
P). The anomalous sea level pressure (SLP) within the area bounded by the l
ongitudes of 130 degrees W and 100 degrees W and the latitudes of 50 degree
s S and 70 degrees S is used as the base variable to determine periods with
7 or more sequential days with positive anomalies in this domain. Using th
ese periods, composites are calculated for the SLP and its anomalies, 500-h
Pa geopotential height anomalies and the 250-hPa and 925-hPa wind vectors i
n the western southern hemisphere (SH). Composites for austral winter and s
ummer exhibit atmospheric circulation features quite similar to those assoc
iated with the blocking episodes in the southeastern Pacific. The correspon
ding composite patterns of the precipitable water (Pw) and 925-hPa temperat
ure anomalies for the South American sector are also discussed. For both se
asons blocking episodes in the southeastern Pacific change the distribution
s of these thermodynamic variables over South America, in particular in its
southern and southeastern regions by reducing (increasing) the Pw and low-
level temperature in the southern South America (the central part of the co
ntinent). Therefore, monitoring the southeastern Pacific circulation patter
ns may lead to improved weather forecast for the South American sector.