Precipitation Analyses

Isopluvial Maps of Washington State were recently completed, under a contract with WSDOT.  Gridded datasets and shape files are available for the entire state for durations of 2-hours and 24-hours for a full range of annual exceedance probabilities.

(Analysis was performed cooperatively with Oregon Climate Service and Jim Wallis of Yale University)

The links below are high resolution images of the precipitation maps.


Mean Annual 24-hr 6-month
2-hr 2-yr 24-hr 2-year
2-hr 10-yr 24-hr 10-year
2-hr 25-yr 24-hr 25-year
2-hr 50-yr 24-hr 50-year
2-hr 100-yr 24-hr 100-year

MGS Engineering Consultants Specializes in statistical, magnitude-frequency, and spatial analyses of storms for use in Engineering Applications

Extended Precipitation and Evaporation Timeseries for Continuous Hydrologic Models


Using precipitation input that is representative of the site under consideration is critical for the accurate computation of runoff and the design of stormwater facilities.  Precipitation and evaporation timeseries have been assembled for most areas of western Washington and are stored in a database file accessed by MGSFlood or in an HSPF WDM file



Extended Precipitation Time Series Report, Pierce County, WA


Extended Precipitation Time Series Report, Western WA