Precipitation Totals and Departures from Normal Product Details
Most of the NERFC precipitation total and departure products are updated daily. The graphics for monthly totals and the accompanying text product are created in the late afternoon on the second of each month for the previous month.
Data Description: The precipitation totals used in these graphics and the accompanying text products are from the 6-hourly County Mean Areal Precipitation (MAP) calculated for use in the Northeast River Forecast Center's Community Hydrologic Prediction System (CHPS.)
Precipitation totals are calculated for the most recently completed Hydrologic Day. For example, the products generated on July 8, 2015 will include data through 12Z on July 8, 2015. The monthly totals and departures are calculated from the first day of the month at 12Z through 12Z on the first day of the next month.
Normals: The "normal" precipitation is derived from PRISM climate data, created at Oregon State University. The 30 year PRISM normals from 1981-2010 are used on products created on or after October 22, 2015. Values from 1971-2000 were used for these graphics and the accompanying text products prior to that date. For more information about PRISM go to https://www.prism.oregonstate.edu/
Acknowledgment: The Precipitation Totals for the counties of Broome, Chemung, Chenango, Cortland, Delaware, Otsego, Steuben, Sullivan and Tioga in New York State are provided by the Middle Atlantic River Forecast Center.
Known Errors: An error was found with the departures from normal for Chemung County New York prior to December 29, 2010. Products created after that date will have the correct values.