891 Forecasting Precipitation Return Intervals: Rethinking How We Communicate High-Impact Precipitation Events

Tuesday, 24 January 2017
4E (Washington State Convention Center )
Tom Dang, NWS, Sacramento, CA

Handout (3.3 MB)

Forecasting and communicating precipitation forecasts is a multi-faceted challenge to the operational

forecaster. The age-old question “What does this forecast mean to me?” is especially applicable to

Quantitative Precipitation Forecasts (QPF), as the forecast units are a vague concept that don’t easily

relate to the user. Climatology adds another potential source for confusion, as an inch of rain can lead to

drastically different consequences depending location and precipitation duration.

NOAA’s Atlas 14 dataset can aid in forecasting and communicating high-impact precipitation events.

Atlas 14 is an extensive catalog of precipitation frequency estimates across much of the Continental

United States, and NOAA provides these datasets in Geographic Information System (GIS) format.

Combining QPF with precipitation frequency estimates yields a Return Interval Forecast, which

calibrates the traditional precipitation forecast based on precipitation duration and climatology. In this

presentation, we take a look at several examples of this experimental product, discuss the potential for

an Impacts Catalog based on Return Interval Forecasts, and share a few instances where the product has

helped clarify our forecast message with core partners.

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