Advancements have been made in identifying teleconnection between various climate phenomena and regional hydrometeorology. This knowledge can be systematically applied to predict regional hydrometeorology to gain lead time for resource and risk management decision making. Adaptations for droughts, floods, and cold and warm weather conditions are necessary for optimal food production and, in many cases, for survival. The El Niño Southern Oscillation (ENSO) climatic phenomenon has been linked to seasonal weather of many regions mainly through rainfall and temperature. The development of El Niño or La Niña has usually opposing regional effects. Its effects are manifested in regional droughts and crop yield reduction, loss of livestock feed, water supply shortage or floods and flood damages, insect population and pathogens, wildfires, etc. A new method has been used to track ENSO development using cumulative sea surface temperature (SST) anomaly and cumulative Southern Oscillation Index (SOI) from freely available data. The relationships of ENSO indices and the Blue Nile hydrology have been shown using an index that tracks cumulative SST anomaly. It has been shown that the Upper Blue Nile basin rainfall and flows have teleconnection to ENSO. Dry years are likely to occur during El Niño years at a confidence level of 90∈% and La Niña years favor wetter condition. The results of this study can be applied to resource management decision making to mitigate drought or flood impacts with a lead time of at least few months. ENSO tracking and forecasting helps prediction of approaching hydrologic conditions to make early water management decisions. A case study with organizational structure and decision making process is presented where ENSO conditions are tracked weekly and results are applied for water management decision making.
