An Extreme Annual Precipitation Anomaly in the Preradiosonde Era

Abstract

he wettest year, by a huge margin, in the instrumental history for the state of New Mexico was 1941. The authors describe the extraordinary magnitude and persistence of above-average precipitation across the seasonal cycle during this year and consider possible climatic causes of this exceptional annual anomaly through examination of a wide variety of historical records and modern analysis tools. Indices of the Pacific decadal oscillation and the El Niño?Southern Oscillation were both extremely positive in 1941, consistent with the historical tendency for above-average precipitation across the southern United States under such conditions. However, the largest precipitation anomalies occurred in transition season months that do not fit the typical seasonality associated with strong ENSO- or PDO-related continental climate anomalies in the more recent historical record. The difficulty in attributing this extreme annual anomaly to any specific climatic cause is a reminder that the radiosonde era provides only a limited sample of natural climatic variability. The number and quality of data sources available for preradiosonde years allows for surprisingly in-depth observational analysis of early twentieth-century climatic anomalies.