{"id":43520,"date":"2026-01-09T11:15:06","date_gmt":"2026-01-09T05:45:06","guid":{"rendered":"https:\/\/www.gujaratweather.com\/?p=43520"},"modified":"2026-01-09T11:15:06","modified_gmt":"2026-01-09T05:45:06","slug":"double-dip-la-nina-expected-to-continue-into-2023-%e0%aa%a1%e0%aa%ac%e0%aa%b2-%e0%aa%a1%e0%aa%bf%e0%aa%aa-%e0%aa%b2%e0%aa%be-%e0%aa%a8%e0%ab%80%e0%aa%a8%e0%aa%be-2023-%e0%aa%ae%e0%aa%be%e0%aa%82-2-22","status":"publish","type":"post","link":"https:\/\/www.gujaratweather.com\/?p=43520","title":{"rendered":"A Historical El Ni\u00f1o (2019-2020) Created By Climatology Update"},"content":{"rendered":"

A Historical El Ni\u00f1o (2019-2020) Created by a Climatology Update<\/h3>\n

9 January 2026<\/strong><\/p>\n

Important Note on ONI Revisions<\/h4>\n

The CPC has implemented its latest climatological base-period update, shifting the reference climatology to 1996\u20132025<\/strong> as part of its routine five-year revision cycle. Adopted in January 2026, this change has materially altered the historical ENSO record<\/strong>\u2014not by changing the ocean, but by changing how anomalies are defined.<\/p>\n

The Oceanic Ni\u00f1o Index (ONI) is calculated as sea-surface temperature anomalies in the Ni\u00f1o-3.4 region relative to a rolling 30-year \u201cnormal.\u201d Each forward shift of this baseline redefines what constitutes normal<\/em> conditions. While such updates often result in a warmer baseline, the latest revision has cooled the Ni\u00f1o-3.4 climatological mean<\/strong>, as clearly reflected in the historical SST climatology.<\/p>\n

As a direct consequence, the period October\u2013December 2019 through February\u2013April 2020<\/strong>, previously classified as ENSO-neutral under the 1991\u20132020<\/strong> baseline, now satisfies the formal threshold for a weak El Ni\u00f1o<\/strong>. This reclassification effectively creates a historical El Ni\u00f1o (2019-2020) event that was never identified in real time<\/strong>.<\/p>\n

Crucially, the underlying oceanic conditions have not changed<\/strong>. What has changed is the statistical reference against which those conditions are measured. This episode demonstrates that ENSO classifications are not absolute physical truths; they are diagnostic constructs<\/strong> that depend explicitly on the chosen climatological baseline.<\/p>\n

For researchers, forecasters, and communicators, this serves as a clear caution: ENSO \u201chistory\u201d is not immutable. When the yardstick is recalibrated, past classifications can\u2014and do\u2014change.\u00a0\"\"<\/a><\/p>\n

\n
\n
\n
\"\"<\/a>
\nThe above CPC ONI Table shows the ENSO Neutral conditions for OND 2019 to FMA 2020
\n<\/strong><\/h5>\n
<\/h5>\n

 <\/p>\n

\"\"<\/a>
\nThe above CPC ONI Table shows a weak El Ni\u00f1o for OND 2019 to FMA 2020<\/strong><\/h5>\n<\/figure>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

A Historical El Ni\u00f1o (2019-2020) Created by a Climatology Update 9 January 2026 Important Note on ONI Revisions The CPC has implemented its latest climatological base-period update, shifting the reference climatology to 1996\u20132025 as part of its routine five-year revision Read More …<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1,7],"tags":[],"class_list":["post-43520","post","type-post","status-publish","format-standard","hentry","category-enso","category-ashok-patel-weather"],"_links":{"self":[{"href":"https:\/\/www.gujaratweather.com\/index.php?rest_route=\/wp\/v2\/posts\/43520","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.gujaratweather.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.gujaratweather.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.gujaratweather.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.gujaratweather.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=43520"}],"version-history":[{"count":5,"href":"https:\/\/www.gujaratweather.com\/index.php?rest_route=\/wp\/v2\/posts\/43520\/revisions"}],"predecessor-version":[{"id":43527,"href":"https:\/\/www.gujaratweather.com\/index.php?rest_route=\/wp\/v2\/posts\/43520\/revisions\/43527"}],"wp:attachment":[{"href":"https:\/\/www.gujaratweather.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=43520"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.gujaratweather.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=43520"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.gujaratweather.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=43520"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}