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<front>
<journal-meta>
<journal-id journal-id-type="publisher">EGUsphere</journal-id>
<journal-title-group>
<journal-title>EGUsphere</journal-title>
<abbrev-journal-title abbrev-type="publisher">EGUsphere</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">EGUsphere</abbrev-journal-title>
</journal-title-group>
<publisher><publisher-name>Copernicus Publications</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/egusphere-2026-5954</article-id>
<title-group>
<article-title>Seasonal Precipitation Predictability Based on Sea Surface Temperature Forecasts From a Cyclostationary Linear Inverse Model</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Breeden</surname>
<given-names>Melissa</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Hoell</surname>
<given-names>Andrew</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Vimont</surname>
<given-names>Daniel</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Toride</surname>
<given-names>Kinya</given-names>
<ext-link>https://orcid.org/0000-0002-5399-0103</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Anderson</surname>
<given-names>Weston</given-names>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Physical Sciences Laboratory, National Oceanic and Atmospheric Administration, Boulder CO, 80305, USA</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Department of Atmospheric and Oceanic Sciences, University of Wisconsin-Madison, Madison WI, 53716, USA</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder CO, 80309, USA</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Department of Geographical Sciences, University of Maryland, College Park MD, 20742, USA</addr-line>
</aff>
<pub-date pub-type="epub">
<day>28</day>
<month>10</month>
<year>2026</year>
</pub-date>
<volume>2026</volume>
<fpage>1</fpage>
<lpage>27</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Melissa Breeden et al.</copyright-statement>
<copyright-year>2026</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/4.0/">https://creativecommons.org/licenses/by/4.0/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-5954/">This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-5954/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-5954/egusphere-2026-5954.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-5954/egusphere-2026-5954.pdf</self-uri>
<abstract>
<p>Developing skillful seasonal precipitation forecasts remains a key challenge over many areas of the world. In this study, we test how much seasonal precipitation forecast skill can be derived from sea surface temperature (SST) forecasts from a cyclostationary linear inverse model (CSLIM) trained on observed estimates of seasonally varying predictable dynamics. Here we introduce a novel method that learns lead- and season-specific relationships between CSLIM SST forecasts and observed precipitation empirical orthogonal functions to generate precipitation forecasts up to one year in advance. Furthermore, we assess the precipitation forecast skill related to modes of SST variability, including the El Ni&amp;ntilde;o / Southern Oscillation (ENSO) and a long-term warming trend.&lt;/p&gt;
&lt;p&gt;Precipitation skill generated using CSLIM SST forecasts is better than climatology for many key rainy seasons worldwide, in many cases 6-12 months in advance. A single ENSO mode, which captures most but not all ENSO variability, is the leading source of precipitation skill for several seasons such as the October-December &amp;lsquo;short&amp;rsquo; rains in East Africa, the main Central America rainy season, and winter precipitation over the southeast and southwest United States. Conversely, a long-term trend accounts for most of the skill over the Sahel. West Pacific SST variability distinct from the ENSO mode contributes to skill in some cases such as the March&amp;ndash;May &amp;lsquo;long&amp;rsquo; rains in East Africa and the Middle East / Southwest Asia region. Some precipitation seasons, such as warm season southeast US precipitation, are not skillful from CSLIM SST forecasts, suggesting a limited or nonlinear relationship between SSTs and precipitation, and/or one that is hindered by seasonally unpredictable dynamics.</p>
</abstract>
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<funding-group>
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<funding-source>National Oceanic and Atmospheric Administration</funding-source>
<award-id>--</award-id>
</award-group>
</funding-group>
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