Observing and Monitoring Drought
Abstract

Abstract Author: John Janowiak

Abstract Title: A tool for monitoring and forecasting the initiation, longevity, and demise of droughts

Abstract: The Precipitation Anomaly Classification (PAC) is a published drought monitoring technique that was developed in the 1980s that classifies levels of drought based on precipitation over the previous three months as determined from monthly rain gauge information. Drought persists until specified criteria are met in succeeding months. The methodology has been updated to incorporate global pentad analyses of satellite-raingauge merged precipitation and numerical model precipitation forecasts. The addition of satellite information increases the utility of the technique by expanding it to regions where rain gauge data are sparse (nonexistent) and the pentad temporal resolution of these analyses means that updates are possible every five days instead of monthly. The use of model forecasts of precipitation yields a predictive aspect to the technique.