Number of Extreme Precipitation Days

The number of extreme precipitation days is calculated using precipitation data sourced from the North American Land Data Assimilation System (NLDAS) (https://ldas.gsfc.nasa.gov/nldas/v2/forcing). This data is initially correlated with U.S. Census blocks and subsequently compiled into larger Census tracts and county-level aggregations, with adjustments made according to population distributions. Each day's precipitation is then evaluated against the 90th percentile value specific to the county, established from historical data. Days with precipitation exceeding this 90th percentile threshold are classified as extreme and tallied to provide a count of extreme precipitation days for each county. This calculation method is provided by the CDC National Environmental Public Health Tracking (https://ephtracking.cdc.gov/indicatorPages )