Entries show station weight (percent), station latitude (degrees N), station longitude (degrees E), and station name for each of the stations in the index.
1 13.65 36.072 -115.163 LAS VEGAS AP 2 16.42 36.551 -114.458 OVERTON 3 16.70 36.279 -116.003 PAHRUMP 4 19.92 36.438 -115.360 DESERT NWR 5 33.31 35.466 -114.922 SEARCHLIGHT
The station weight is based on the average annual precipitation at that station, so that a wet station contributes more to the final index that does a dry station. The final weight is normalized so that the sum of all the weights adds up to 100%.
Stations are selected based on two criteria. 1) They must have a relatively long (50 year or more) record with few interruptions. 2) They must be updated nearly every day by the California Nevada River Forecast Center.