Evaluating predictability limits of North American winter precipitation

Abstract Given that seasonal precipitation predictions over North America are not particularly skillful, assessing whether forecast system refinements can enhance skill and societal usefulness of seasonal forecasts is important. We investigate by using average predictability time (APT) analysis to f...

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Main Authors: Joseph P. Clark, Nathaniel C. Johnson
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:npj Climate and Atmospheric Science
Online Access:https://doi.org/10.1038/s41612-025-01132-7
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author Joseph P. Clark
Nathaniel C. Johnson
author_facet Joseph P. Clark
Nathaniel C. Johnson
author_sort Joseph P. Clark
collection DOAJ
description Abstract Given that seasonal precipitation predictions over North America are not particularly skillful, assessing whether forecast system refinements can enhance skill and societal usefulness of seasonal forecasts is important. We investigate by using average predictability time (APT) analysis to filter wintertime, seasonal precipitation hindcasts provided by the Seamless System for Prediction and Earth System Research. Using this method, which decomposes forecasts into predictable modes, we find limited potential to improve seasonal precipitation forecasts over North America owing to the subseasonal predictability timescales of most APT modes. Nevertheless, more skillful forecasts of APT mode 2, which is tied to equatorial Pacific convection and has a predictability timescale of about 220 days, may improve seasonal precipitation forecasts over North America. We demonstrate that predictions for the winters of 2015–2016 and 2021–2022, which featured notable forecast errors over western North America, may have been improved with better predictions of this second APT mode.
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spelling doaj-art-76bf0c31533e4dccb2e0cf41ef8b29292025-08-20T03:03:27ZengNature Portfolionpj Climate and Atmospheric Science2397-37222025-07-018111210.1038/s41612-025-01132-7Evaluating predictability limits of North American winter precipitationJoseph P. Clark0Nathaniel C. Johnson1Program in Atmospheric and Oceanic Sciences, Princeton UniversityNational Oceanic and Atmospheric Administration/Geophysical Fluid Dynamics LaboratoryAbstract Given that seasonal precipitation predictions over North America are not particularly skillful, assessing whether forecast system refinements can enhance skill and societal usefulness of seasonal forecasts is important. We investigate by using average predictability time (APT) analysis to filter wintertime, seasonal precipitation hindcasts provided by the Seamless System for Prediction and Earth System Research. Using this method, which decomposes forecasts into predictable modes, we find limited potential to improve seasonal precipitation forecasts over North America owing to the subseasonal predictability timescales of most APT modes. Nevertheless, more skillful forecasts of APT mode 2, which is tied to equatorial Pacific convection and has a predictability timescale of about 220 days, may improve seasonal precipitation forecasts over North America. We demonstrate that predictions for the winters of 2015–2016 and 2021–2022, which featured notable forecast errors over western North America, may have been improved with better predictions of this second APT mode.https://doi.org/10.1038/s41612-025-01132-7
spellingShingle Joseph P. Clark
Nathaniel C. Johnson
Evaluating predictability limits of North American winter precipitation
npj Climate and Atmospheric Science
title Evaluating predictability limits of North American winter precipitation
title_full Evaluating predictability limits of North American winter precipitation
title_fullStr Evaluating predictability limits of North American winter precipitation
title_full_unstemmed Evaluating predictability limits of North American winter precipitation
title_short Evaluating predictability limits of North American winter precipitation
title_sort evaluating predictability limits of north american winter precipitation
url https://doi.org/10.1038/s41612-025-01132-7
work_keys_str_mv AT josephpclark evaluatingpredictabilitylimitsofnorthamericanwinterprecipitation
AT nathanielcjohnson evaluatingpredictabilitylimitsofnorthamericanwinterprecipitation