Skip to main content
USGS - science for a changing world

Standardized precipitation index forecast September - November 2012 (based on COLA 7-mo weather forecast)


Original Data Basin Creation Date
2012-10-11 15:28:25
Original Data Basin Modified Date
2012-10-11 15:28:25


The Standardized Precipitation Index (SPI) is a probability index that can be calculated for different time periods to indicate periods of abnormal wetness or dryness. SPI is derived solely from monthly precipitation and can be compared across regions with different climates. The SPI is an index based on the probability of recording a given amount of precipitation, and the probabilities are standardized so that an index of zero indicates the median precipitation amount (half of the historical precipitation amounts are below the median, and half are above the median). This dataset shows the average 12-month SPI (in classes ranging from extremely wet to extremely dry) for the three-month forecast period indentified in the dataset [...]


Preview Image



  • Data Basin



Data source
United States Forest Service, MAPSS team--Raymond Drapek<br />
Harvested on Fri May 23 09:36:51 MDT 2014 from Data Basin Service

Additional Information


Type Scheme Key
UniqueKey Data Basin f0367e9bb1c74602a5856de06eb7fa4b

Item Actions

View Item as ...

Save Item as ...