{"title":"Evaluating predictability limits of North American winter precipitation","authors":"Joseph P. Clark, Nathaniel C. Johnson","doi":"10.1038/s41612-025-01132-7","DOIUrl":null,"url":null,"abstract":"<p>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.</p>","PeriodicalId":19438,"journal":{"name":"npj Climate and Atmospheric Science","volume":"9 1","pages":""},"PeriodicalIF":8.5000,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"npj Climate and Atmospheric Science","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1038/s41612-025-01132-7","RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"METEOROLOGY & ATMOSPHERIC SCIENCES","Score":null,"Total":0}
引用次数: 0
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.
期刊介绍:
npj Climate and Atmospheric Science is an open-access journal encompassing the relevant physical, chemical, and biological aspects of atmospheric and climate science. The journal places particular emphasis on regional studies that unveil new insights into specific localities, including examinations of local atmospheric composition, such as aerosols.
The range of topics covered by the journal includes climate dynamics, climate variability, weather and climate prediction, climate change, ocean dynamics, weather extremes, air pollution, atmospheric chemistry (including aerosols), the hydrological cycle, and atmosphere–ocean and atmosphere–land interactions. The journal welcomes studies employing a diverse array of methods, including numerical and statistical modeling, the development and application of in situ observational techniques, remote sensing, and the development or evaluation of new reanalyses.