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high latitudes (from 35 degrees to 70 degrees North). Although Pacific-based indexes are more ‘intuitive’ for Colorado in that most of the ‘weather’ that effects arrives from areas of Pacific origin. It is important to examine large-scale variability in the Atlantic as weather in this region of the Northern Hemisphere can act to influence the storms that arrive from Pacific regions, especially if the departures are strong. Atlantic Multi-Decadal Oscillation (AMO): This index is similar in nature to that of the PDO in that it is a large-scale departure of SST across the northern and southern Atlantic Oceans. Recent research has touched upon large-scale departures of precipitation anomalies in various ‘phases’ of the AMO merged with the PDO. Thus, this is one variable that will be included. Preliminary Results The summary of the results will be focused on a basin-by-basin basis as outlined in the Introduction section. For each Water Division and in the applicable area, the District-level findings will first present the basin-average precipitation correlations for the various seasonal periods (December-March, April-June and July-September precipitation periods) the seasonal temperature correlations (performed on a Division- wise basis) and the correlations with seasonal (April-September) runoff followed by the multi-year (2-year) relationships. In the Colorado/Yampa-White River basins, the division of the basins was not done specifically at the District level but were ‘naturally’ divided by sub-basins according to geography and acted as a natural starting point for these analyses. The determination of which sub-basins would be analyzed was determined through a combination of coordination with professionals who are knowledgeable of water supply systems and operations in these areas. As noted in the section above, many of these computed relationships are available if only both the HCI and precipitation/streamflow data are available. Both sets of data are limited in terms of their time frame with the HCI variables limited to the 1950 and later thus limiting this analysis to ~55 years of data. In other sections of this report, naturalized streamflow was the limiting data factor as the computation of this variable is complex given the system of man-made inflow/outflows that are present. This limiting factor was most notable in the daily naturalized streamflow calculations which are quite cumbersome and the State should be commended for the current set of data that does exist. As the reader proceeds through the report one will find some range of variability in the HCI impacts through the various Divisions and even across District. Much attention has been given to the ENSO phenomenon and its impacts on climatic variability across the Western US and the world for that matter. ENSO does show up as a relevant variable on the water supply variables in the state however, there are other factors including those measured in the Atlantic that offer insight to the season and multi- 6