Merge pull request #741 from bilawalsidhu/fix/cyclone-advisory-time

fix(cyclones): accept advisories NHC publishes before their nominal time

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Changelog
 
+- Cyclone advisories no longer go dark while NHC publishes an advisory ahead
+  of its nominal time: advisory and position times up to 90 minutes ahead of
+  the server clock are accepted (previously 5 minutes), so the whole feed is
+  not rejected for about half an hour each advisory cycle.
+
 - Flights age out vanished aircraft again. OpenSky's routine position-less rows
   no longer mark every snapshot partial, which had kept vanished and landed
   aircraft at full opacity for up to five minutes; those rows retain only their

docs/CURRENT-STATE.md

@@ -339,7 +339,12 @@ Cyclones combine fixed NHC/CPHC status and summary GIS endpoints through a bound
 same-origin provider. The status endpoint lacks browser CORS; each installation
 fetches keyless public sources at runtime, with no centralized ingestion service.
 The five-minute snapshot covers Atlantic and eastern/central North Pacific only.
-Current positions, advisory issue time and position time stay distinct. Tracks,
+Current positions, advisory issue time and position time stay distinct. NHC may
+release an advisory before its nominal time (routinely up to about 30 minutes,
+rarely about an hour), so advisory issue and position times up to and including
+90 minutes ahead of the server clock are accepted; 90 minutes is this app's
+tolerance, not an NHC limit. Later, non-canonical, or more than 12-hour-old
+times still reject the status snapshot. Tracks,
 forecast lead-hour points and cones render only when all source parts match the
 status advisory; a newer status shows its position with geometry pending rather
 than relabeling older geometry. The cone represents forecast center uncertainty,

server/providers/cyclones.js

@@ -41,6 +41,9 @@ function number(value, min, max) {
   const n = Number(value);
   return Number.isFinite(n) && n >= min && n <= max ? n : null;
 }
+// NHC stamps an advisory with its nominal time (e.g. 03:00Z) and publishes it
+// up to about half an hour before; allow that, but not a clock far ahead.
+const EARLY_ADVISORY_MS = 90 * 60_000;
 function iso(value, now) {
   if (
     typeof value !== 'string' ||
@@ -50,7 +53,7 @@ function iso(value, now) {
   const n = Date.parse(value);
   if (
     !Number.isFinite(n) ||
-    n > now + 5 * 60_000 ||
+    n > now + EARLY_ADVISORY_MS ||
     now - n > 12 * HOUR ||
     new Date(n).toISOString().replace('.000Z', 'Z') !==
       value.replace('.000Z', 'Z')

src/data/cyclonesProxy.test.mjs

@@ -162,6 +162,44 @@ test('malformed, duplicate, oversized, future and expired status is rejected rat
   assert.deepEqual(parseCycloneStatus({ activeStorms: [] }, NOW), []);
 });
 
+test('advisories published before their nominal time are accepted, far-future ones are not', () => {
+  // NHC wrote the 03:00Z advisory at 02:34Z.
+  const early = Date.UTC(2026, 8, 16, 2, 34);
+  assert.equal(parseCycloneStatus(status(), early)[0].issuedAt, TIME);
+  assert.throws(
+    () => parseCycloneStatus(status(), Date.UTC(2026, 8, 16, 1, 25)),
+    /invalid_cyclone_data/,
+  );
+});
+
+test('advisory and position times are bounded at 90 minutes ahead and 12 hours old', () => {
+  const MINUTE = 60_000;
+  const at = (offsetMs) => new Date(NOW + offsetMs).toISOString();
+  const fields = {
+    issuedAt: (value) =>
+      status({
+        forecastAdvisory: {
+          advNum: '010',
+          issuance: value,
+          url: 'https://www.nhc.noaa.gov/text/MIATCMEP5.shtml',
+        },
+      }),
+    positionAt: (value) => status({ lastUpdate: value }),
+  };
+  for (const [field, payload] of Object.entries(fields)) {
+    for (const offset of [90 * MINUTE, -12 * 60 * MINUTE]) {
+      const [storm] = parseCycloneStatus(payload(at(offset)), NOW);
+      assert.equal(storm[field], at(offset), `${field} ${offset}`);
+    }
+    for (const offset of [90 * MINUTE + 1, -12 * 60 * MINUTE - 1])
+      assert.throws(
+        () => parseCycloneStatus(payload(at(offset)), NOW),
+        /invalid_cyclone_data/,
+        `${field} ${offset}`,
+      );
+  }
+});
+
 test('coherent geometry is retained with holes/dateline while older advisory geometry is omitted', () => {
   const storms = parseCycloneStatus(status(), NOW);
   const parts = collections();