Electrical Power for Valdez and the Copper River Basin-1981

snowfields and glacier areas on the southern slopes of these mountains.The lowest temperatures recorded at Valdez appear to be due to thedownslope flow of cold air, since the lowest temperatures on retord haveoccurred durinq periods with 1 ittle or no wind, providing ideal conditionsfor the cold air to flow down onto the flat glacial plain. Thenearby snow and icefields combine with the ocean areas to provide amoderating effect on summertime high temperatures which seldom reach themiddle 80's. The surrounding mountains tend to produce considerablevariations in practically all weather elements within relatively shortdistances.The continental region, whic~ covers Klutina and Tonsina Lakes andmost of their watersheds, has mean maximum summer temperatures in the midto upper 60's, and mean minimum winter temperatures around 20 below zero,Fahrenheit. The mean annual precipitation is between 10 and 20 inches,at least in lower elevations. Heavier amounts occur in the upperelevations. Surface winds are light compared to those found along thecoast.In the transition region, where the conditions are between those ofthe maritime and continental regions, temperature extremes most resembleth~ continental zone's, while precipitation amounts range from light toheavy enough to maintain glaciers. The Tsina River and Tiekel Riverdrainages are considered to be in the transitional zone. Surface windsin the transition region range between coastal and interior conditions,including some channeled winds through mountain valleys.While the climatic data from the Valdez weather station is fairlyrppresentative of the sea level conditions in the study area, lowertemperatures and greater precipitation will occur over most to the higherdrainage basins. Based on 7 years of streamflow records, which typifythe amount of precipitation in the areas being studied, the Solomon Gulchgage recorded an average annual discharge of 104,300 acre-feet for a19-square mile drainage basin, yielding a basin average of 103 inchesrunoff per year.Temperature:The four climatological stations in the area are located at CopperCenter, Glennallen, Valdez, and Cordova. The records for Glennallen andCopper (enter are incomplete and are not presented in this analysis. Asummary of the average monthly temperatures for Valdez and Cordova ispresented below.LA-2