New Mexico Geological Society Annual Spring Meeting — Abstracts

We develop an objective index to indicate the start of the monsoon season in central New Mexico using data from several measuring stations around Albuquerque. The weather variables being considered include dew point, daily precipitation, relative humidity, and wind. With these data we are attempting to define and quantify noticeable changes that mark the onset of a prolonged summer rainy season. We find that there appears to be dew point threshold (analogous to monsoon onset indices developed for sites in Arizona) that may indicate the start of the monsoon, consistent with the onset of persistent precipitation that nearly matches the accepted historic start date of July 7th.

At this time we are refining the monsoon onset criterion based on precipitation and dew point, to take into account "false starts" that may be associated with transient mid-latitude weather systems but are not associated with a large-scale monsoon circulation. We will develop a time series of onset dates to examine the relationships between monsoon onset, total seasonal precipitation, and possible antecedent predictors of the monsoon, and to consider whether the onset date has been changing during the past several decades.