Standardized precipitation index forecast May - July 2012 (based on COLA 7-mo weather forecast)
Dataset Identification:
Resource Abstract:
<br /> 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. <br /> <br /> SPI is derived solely from monthly precipitation and can
be compared across regions with different climates. <br /> <br /> 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). <br /> <br /> 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 title. Negative (i.e., dry) values of the 12-month SPI are closely associated with a high
potential for wildland fire. <br /> <br /> SPI was calculated from the long-term precipitation record up to the last observed
month and from projected monthly precipitation values provided by the weather model identified in the dataset title. <br />
<br /> Future climate forecasts are available through cooperation with the International Research Institute for Climate Prediction
(IRI) of Columbia University which provides monthly updates of 7-month future climate forecasts from five different general
circulation models (GCMs) of the global atmosphere. GCM results come from the University of Maryland (COLA), the University
of Hamburg (ECHAM4.5), the National Weather Services Climate Prediction Center (NCEP), NASAs Goddard Institute of Space Studies
(NSIPP), and the Scripps Oceanographic Institute (ECPC). <br /> <br /> <br />
Citation
Title Standardized precipitation index forecast May - July 2012 (based on COLA 7-mo weather forecast)