EPS Products Reference Guide

The EPS Products Reference Guide is intended to improve forecasters' understanding of EPS products so they can provide probabilistic and uncertainty forecast information to customers. The Guide provides information about commonly used ensemble products. Each has a description, tips for interpreting and using it effectively, a list of its strengths and weaknesses, and practice exercises. The products are introduced via conceptual examples while the exercises use actual products from various national hydrometeorology services.

Note that the Introduction to EPS Theory lesson should be taken before accessing the Guide since it presents the basic information needed to understand the products. The Guide is designed to serve as reference material so the products can be accessed in any order, as needed. It does not have a quiz.

The products are grouped as follows:

• Generalized View of Distribution: These products provide a general statistical representation of the ensemble distribution. They offer a quick view of common statistical measures, including mean, median, quantiles and spread, or standard deviation. Some products are displayed spatially in plan-view while others are temporal charts for a single location.
• Individual Members: These products provide a view of all individual ensemble members so you can interpret the shape of the distribution and presence of member clustering. Some products are displayed spatially in plan-view while others are temporal charts for a single location.
• Criteria-Based Probabilities: These plan-view products provide a criteria-based view of the ensemble forecast to help with the issuance of watches, warnings, and advisory criteria and to communicate about industry-based thresholds to end users.
• Climatology Enhanced Products: These plan-view products compare ensemble forecasts to climatological data (model climate, reanalysis climatology, or observed climatology) to help you identify unusual or extreme forecast conditions. They are especially useful for those unfamiliar with an area's climatology.