Snowpack summary data are contained in files named swe_kpbs_YYYY.txt, where YYYY represents the 4-digit water year. The water year here in CA starts on Oct 1 and end on the following Sep 30. For example, water year 2016 starts on Oct 1, 2015 and ends on Sep 30, 2016. These files only contain data from Oct 1 to May 31. The snow data is the Snow Water Equivalent (SWE) and is the amount of liquid water if the snow was melted. There are summary data for 4 regions: Northern, Central, and Southern Sierra and the Upper Colorado River Basin. The data presented are multi-station averages. The individual stations used for each region are taken from the California Department of Water Resources (DWR) for the Sierra regions and from the National Resources Conservation Service (NRCS) for the Upper Colorado. The data contain 2 variables that can be used to see how the year is shaping up with respect to a "normal" year. First there is the PON, which is the amount of SWE compared to the normal amount of SWE for that day. For instance if the PON on Nov 30 was 30%, then the amount of SWE was 30% of what was usually measured on November 30. A note of caution on PON: early and late in the water year a small amount of snowfall can yield a relatively large value of PON. This is because the normal amount of SWE at these times is rather low. The other value is PON_APR1 which compares the SWE on a given day to what is normally observed on April 1. April 1 is traditionally used in California to measure the snow pack as it is approximately the time when the snow level reaches a maximum value. Using PON_APR1 can give some idea of how close the region is to receiving its total snow amount for the season. Each file contains 15 columns: Column 1 = year Column 2 = month Column 3 = day Columns 4-6: Northern Sierra Region Column 4 = SWE (in inches) Column 5 = % of normal for this day (PON) Column 6 = % of the normal April 1 value (PON_APR1) Columns 7-9: Central Sierra Region Column 7 = SWE (in inches) Column 8 = % of normal for this day (PON) Column 9 = % of the normal April 1 value (PON_APR1) Columns 10-12: Southern Sierra Region Column 10 = SWE (in inches) Column 11 = % of normal for this day (PON) Column 12 = % of the normal April 1 value (PON_APR1) Columns 13-15: Upper Colorada River Region Column 13 = SWE (in inches) Column 14 = % of normal for this day (PON) Column 15 = % of the normal April 1 value (PON_APR1) The data file for the current water year will be updated on a daily basis at approximately 9am PST.