The Extreme Precipitation Group (EPG) consists of nationally-recognized experts in precipitation analyses, development of Probable Maximum Precipitation (PMP) estimates, regional precipitation-frequencies, Probabilistic Flood Hazard Analysis (PFHA) using stochastic flood modeling, and storm analyses using geographic information systems.  Members of the team have served on Independent Review Boards for site-specific PMP studies and for Probable Maximum Flood studies for national and international projects.  The team has been formed to conduct precipitation analyses for a variety of engineering applications.


The EPG team consists of:

              ——- Atmospheric Sciences Consulting Ed Tomlinson
Applied Climate Services George Taylor
mgs_small MGS Engineering Mel Schaefer, Bruce Barker
MetStat, Inc. Tye Parzybok, Jason Caldwell

Overview of EPG Capabilities by Discipline

Site-Specific and Regional Probable Maximum Precipitation (PMP) Studies

EPG has extensive experience in conducting analyses of extreme precipitation events and developing site-specific estimates of PMP and generalized estimates of PMP for regional areas. This includes numerous studies in the United States as well as international studies. Members of the team are responsible for the majority of new methodologies and advancements that have been made over the past decade.

Analysis of Extreme Precipitation Events

EPG personnel have evaluated the spatial and temporal precipitation characteristics of hundreds of extreme storms to support a variety of meteorological engineering applications. Our team is led by storm analysis experts who use MetStorm®, the Storm Precipitation Analysis System (SPAS) and other hydrometeorological tools and techniques for analyzing storm precipitation. Measured rain gauge, NEXRAD radar, climatological and satellite-estimated precipitation data are used to develop storm analytics to support the development of PMP estimates. Detailed storm analysis results are also used in developing spatial and temporal storm templates for use in stochastic flood modeling for probabilistic flood hazard analysis.

Regional Precipitation-Frequency Analysis

Regional L-moment analysis methods are used in conducting precipitation-frequency studies for watersheds and for large regional areas. Numerous large area and watershed-specific regional analyses have been conducted by team members for locations across the United States and in Alberta and British Columbia. The team is led by the developers of L-RAP, commercial software that was specifically designed for conducting large area regional precipitation-frequency analyses.  Other team members have contributed to the development of NOAA Atlas 14, Precipitation-Frequency Estimates for the U.S. (NOAA’s National Weather Service).

Watershed Precipitation-Frequency Relationships for Flood Modeling

Watershed precipitation-frequency relationships are used in conducting stochastic flood modeling for development of Hydrologic Hazard Curves used in risk assessments. The effort includes the use of L-moment regional precipitation-frequency analysis and the spatial and temporal analysis of historical storms. The team is led by the developers of the current technology in the U.S. for developing watershed precipitation-frequency relationships including an analysis of uncertainties. Precipitation-frequency relationships developed from these analyses are one of the principal inputs to the Stochastic Event Flood Model (SEFM) which is used to develop hydrologic hazard curves for risk assessments.

Click here for a list of publications by EPG members:   EPG_Publications


Probabilistic Estimates of Probable Maximum Precipitation


Site-Specific Springtime Maximum Rainfall with Storm Maximization and Transposition


Application of SEFM to the Campbell River System in British Columbia


Uncertainty Analysis for Probable Maximum Precipitation Estimates


Basin-Average Precipitation Frequency Relationships