From 66ea77237f665332a9210633f54fd4d0547dd45e Mon Sep 17 00:00:00 2001
From: Rudy Celekli <rudy@gradiahq.com>
Date: Sat, 24 Oct 2026 00:17:38 -0400
Subject: [PATCH 1/2] fix(cyclones): label NHC classification codes by their
 published meanings

---
 src/i18n/locales/es.json           | 1 +
 src/i18n/locales/ru.json           | 1 +
 src/i18n/locales/zh-CN.json        | 1 +
 src/layers/cyclones/index.js       | 9 ++++++---
 src/layers/cyclones/index.test.mjs | 7 ++++---
 5 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/i18n/locales/es.json b/src/i18n/locales/es.json
index fd55b2e25..4fe130f23 100644
--- a/src/i18n/locales/es.json
+++ b/src/i18n/locales/es.json
@@ -1153,6 +1153,7 @@
   "OpenStreetMap · community mapped": "OpenStreetMap · mapeado por la comunidad",
   "Atlantic and eastern/central North Pacific; not worldwide cyclone coverage.": "Atlántico y Pacífico Norte oriental/central; no es una cobertura mundial de ciclones.",
   "Potential tropical cyclone": "Posible ciclón tropical",
+  "Post-tropical cyclone": "Ciclón postropical",
   "Hurricane": "Huracán",
   "Tropical storm": "Tormenta tropical",
   "Tropical depression": "Depresión tropical",
diff --git a/src/i18n/locales/ru.json b/src/i18n/locales/ru.json
index 442312de2..978640951 100644
--- a/src/i18n/locales/ru.json
+++ b/src/i18n/locales/ru.json
@@ -1169,6 +1169,7 @@
   "OpenStreetMap · community mapped": "OpenStreetMap · данные сообщества",
   "Atlantic and eastern/central North Pacific; not worldwide cyclone coverage.": "Атлантика и восточная/центральная часть северного Тихого океана; покрытие циклонов не глобальное.",
   "Potential tropical cyclone": "Потенциальный тропический циклон",
+  "Post-tropical cyclone": "Посттропический циклон",
   "Hurricane": "Ураган",
   "Tropical storm": "Тропический шторм",
   "Tropical depression": "Тропическая депрессия",
diff --git a/src/i18n/locales/zh-CN.json b/src/i18n/locales/zh-CN.json
index fa08cca1f..01c495a27 100644
--- a/src/i18n/locales/zh-CN.json
+++ b/src/i18n/locales/zh-CN.json
@@ -530,6 +530,7 @@
   "Cyclone advisories unavailable": "气旋公告不可用",
   "Cyclone data unavailable": "气旋数据不可用",
   "Potential tropical cyclone": "潜在热带气旋",
+  "Post-tropical cyclone": "后热带气旋",
   "Hurricane": "飓风",
   "Tropical storm": "热带风暴",
   "Tropical depression": "热带低压",
diff --git a/src/layers/cyclones/index.js b/src/layers/cyclones/index.js
index bcd66923a..2ef663b15 100644
--- a/src/layers/cyclones/index.js
+++ b/src/layers/cyclones/index.js
@@ -41,13 +41,16 @@ const ADVISORIES_UNAVAILABLE = msg('Cyclone advisories unavailable');
 const SERVER_REASONS = new Set([msg('Cyclone data unavailable')]);
 const errorText = (error) =>
   error && (SERVER_REASONS.has(error) ? t(error) : translateKnown(error));
+// NHC's Tropical Cyclone Status JSON reference: PTC is post-tropical, PC is a
+// potential tropical cyclone, and subtropical systems are STS and STD.
 const CLASSIFICATION_NAMES = Object.freeze({
-  PTC: msg('Potential tropical cyclone'),
+  PC: msg('Potential tropical cyclone'),
+  PTC: msg('Post-tropical cyclone'),
   HU: msg('Hurricane'),
   TS: msg('Tropical storm'),
   TD: msg('Tropical depression'),
-  SS: msg('Subtropical storm'),
-  SD: msg('Subtropical depression'),
+  STS: msg('Subtropical storm'),
+  STD: msg('Subtropical depression'),
 });
 const classificationName = (code) =>
   Object.hasOwn(CLASSIFICATION_NAMES, code)
diff --git a/src/layers/cyclones/index.test.mjs b/src/layers/cyclones/index.test.mjs
index 3a7fbdfc7..aff654659 100644
--- a/src/layers/cyclones/index.test.mjs
+++ b/src/layers/cyclones/index.test.mjs
@@ -513,12 +513,13 @@ test('only the latest queued focus runs and an unchanged selection survives refr
 });
 test('classification display expands known codes without altering the source or guessing unknown meanings', async () => {
   for (const [code, label] of [
-    ['PTC', 'Potential tropical cyclone'],
+    ['PC', 'Potential tropical cyclone'],
+    ['PTC', 'Post-tropical cyclone'],
     ['HU', 'Hurricane'],
     ['TS', 'Tropical storm'],
     ['TD', 'Tropical depression'],
-    ['SS', 'Subtropical storm'],
-    ['SD', 'Subtropical depression'],
+    ['STS', 'Subtropical storm'],
+    ['STD', 'Subtropical depression'],
     ['EX', 'EX'],
     ['UNKNOWN', 'UNKNOWN'],
   ]) {

From 7276e300ebace8e4626612c1deb679331307c4a1 Mon Sep 17 00:00:00 2001
From: Rudy Celekli <rudy@gradiahq.com>
Date: Sat, 24 Oct 2026 00:18:37 -0400
Subject: [PATCH 2/2] docs(changelog): add cyclone classification fragment

---
 changelog.d/1349-cyclone-classification-codes.md | 3 +++
 1 file changed, 3 insertions(+)
 create mode 100644 changelog.d/1349-cyclone-classification-codes.md

diff --git a/changelog.d/1349-cyclone-classification-codes.md b/changelog.d/1349-cyclone-classification-codes.md
new file mode 100644
index 000000000..c22debfa1
--- /dev/null
+++ b/changelog.d/1349-cyclone-classification-codes.md
@@ -0,0 +1,3 @@
+- Label NHC cyclone classifications by their published meanings: `PTC` is a
+  post-tropical cyclone, `PC` a potential tropical cyclone, and subtropical
+  systems arrive as `STS` and `STD` (rudycelekli, #1349).