An ALARMS climatology of Gulf of California moisture surges and the associated precipitation, 1993-2004

This study applies the ALARMS (Assessing Low-level AtmospheRic Moisture using Soundings) method to 12 years of data from Phoenix, Arizona; Tucson, Arizona; Yuma, Arizona; and Empalme, Mexico, in order to establish a climatology of low-level moisture surges from the Gulf of California and their effects on precipitation. There are 64 events detected using the available data, and data inventories are used to estimate the actual number of events that occurred at each station for every year. Surge totals are consistent with previous research. Interseasonal variability cannot be significantly related to ENSO, but intraseasonal variability appears to be related to certain phases of the MJO. Composite soundings illustrate the atmospheric profile of typical surges, and it is clear that surface moisture values at Yuma, Arizona, are not consistent with moisture content in the low levels above the surface. Precipitation analyses show that increased low-level moisture significantly increases the amount of rainfall at each gauge as well as the number of stations receiving measurable precipitation. Also, rainfall is more likely on days with higher dewpoints, and gulf surges appear to significantly increase precipitation across the study area.