fix(wind): restore model rendering and show valid time

server/providers/wind/catalog.js

@@ -14,3 +14,16 @@ export function selectLatestGfsCycle(nowMs, { availabilityLagMs = 5 * 3600_000 }
   date.setUTCHours(hour);
   return { date: date.toISOString().slice(0, 10).replaceAll('-', ''), hour };
 }
+
+/**
+ * Round a time offset to the nearest published GFS forecast step so the field
+ * shown is the one valid closest to now, not always the analysis (f000).
+ * GFS 0.25° is hourly through f120, then every 3 h through f384.
+ * @param {number} hours - Hours elapsed since the cycle run time.
+ * @returns {number} A valid forecast step.
+ */
+export function nearestGfsStep(hours) {
+  const value = Math.max(0, Number.isFinite(hours) ? hours : 0);
+  const step = value <= 120 ? Math.round(value) : Math.round(value / 3) * 3;
+  return Math.max(0, Math.min(384, step));
+}

server/providers/wind/gfs.js

@@ -88,14 +88,24 @@ export async function fetchRange({
   return buffer;
 }
 
-import { GFS_BUCKET, gfsObjectKey, selectLatestGfsCycle } from './catalog.js';
+import { GFS_BUCKET, gfsObjectKey, selectLatestGfsCycle, nearestGfsStep } from './catalog.js';
 import { decodeWindGribMessage } from './decode.js';
 import { resampleWindGrid } from './grid.js';
 
-/** Fetch and decode the latest GFS 10 m wind field. */
+/** Fetch and decode the GFS 10 m wind field valid closest to now. */
 export async function fetchGfsWind({ fetchImpl = fetch, now = () => Date.now(), targetDx = 1, decodeImpl = decodeWindGribMessage } = {}) {
-  const cycle = selectLatestGfsCycle(now());
-  const base = `https://${GFS_BUCKET}.s3.amazonaws.com/${gfsObjectKey(cycle)}`;
+  const nowMs = now();
+  const cycle = selectLatestGfsCycle(nowMs);
+  const runMs = Date.UTC(
+    Number(cycle.date.slice(0, 4)),
+    Number(cycle.date.slice(4, 6)) - 1,
+    Number(cycle.date.slice(6, 8)),
+    cycle.hour,
+  );
+  // Pick the forecast step whose valid time is closest to now, so the layer
+  // shows the freshest field the cycle offers instead of the analysis.
+  const forecastHour = nearestGfsStep((nowMs - runMs) / 3600_000);
+  const base = `https://${GFS_BUCKET}.s3.amazonaws.com/${gfsObjectKey({ ...cycle, forecastHour })}`;
   const index = await fetchText({ url: `${base}.idx`, fetchImpl });
   const ranges = windMessageRanges(parseGfsIdx(index.toString()));
   const [uBuffer, vBuffer] = await Promise.all([
@@ -104,5 +114,7 @@ export async function fetchGfsWind({ fetchImpl = fetch, now = () => Date.now(),
   ]);
   const [u, v] = await Promise.all([decodeImpl(uBuffer), decodeImpl(vBuffer)]);
   const grid = resampleWindGrid({ u: u.values, v: v.values, ni: u.ni, nj: u.nj, lo1: u.lo1, la1: u.la1, di: u.di, dj: u.dj, dx: targetDx, dy: targetDx });
-  return { cycle: { ...cycle, forecastHour: 0, runIso: `${cycle.date.slice(0, 4)}-${cycle.date.slice(4, 6)}-${cycle.date.slice(6)}T${String(cycle.hour).padStart(2, '0')}:00:00.000Z` }, level: '10 m above ground', units: 'm/s', grid };
+  const runIso = new Date(runMs).toISOString();
+  const validIso = new Date(runMs + forecastHour * 3600_000).toISOString();
+  return { cycle: { ...cycle, forecastHour, runIso, validIso }, level: '10 m above ground', units: 'm/s', grid };
 }

server/providers/wind/ifs.js

@@ -80,7 +80,20 @@ export function ifsWindRanges(entries) {
 }
 
 /**
- * Fetch and decode the latest IFS 10 m wind field.
+ * Round a time offset to the nearest published IFS forecast step. IFS 0.25°
+ * oper is 3-hourly through f144 (00/12z) or f90 (06/18z).
+ * @param {number} hours - Hours elapsed since the cycle run time.
+ * @param {number} cycleHour - The cycle hour (0, 6, 12 or 18).
+ * @returns {number} A valid forecast step.
+ */
+export function nearestIfsStep(hours, cycleHour) {
+  const max = cycleHour === 6 || cycleHour === 18 ? 90 : 144;
+  const value = Math.max(0, Number.isFinite(hours) ? hours : 0);
+  return Math.max(0, Math.min(max, Math.round(value / 3) * 3));
+}
+
+/**
+ * Fetch and decode the IFS 10 m wind field valid closest to now.
  * @param {{fetchImpl?: Function, now?: Function, targetDx?: number,
  *   decodeImpl?: Function}} [options]
  * @returns {Promise<{cycle: object, level: string, units: string, grid: object}>}
@@ -91,8 +104,17 @@ export async function fetchIfsWind({
   targetDx = 1,
   decodeImpl = decodeWindGribMessage,
 } = {}) {
-  const cycle = selectLatestIfsCycle(now());
-  const urls = ifsObjectUrls(cycle);
+  const nowMs = now();
+  const cycle = selectLatestIfsCycle(nowMs);
+  const runMs = Date.UTC(
+    Number(cycle.date.slice(0, 4)),
+    Number(cycle.date.slice(4, 6)) - 1,
+    Number(cycle.date.slice(6, 8)),
+    cycle.hour,
+  );
+  // Show the field valid closest to now rather than always the analysis.
+  const forecastHour = nearestIfsStep((nowMs - runMs) / 3600_000, cycle.hour);
+  const urls = ifsObjectUrls({ ...cycle, step: forecastHour });
   const index = await fetchText({ url: urls.index, fetchImpl });
   const ranges = ifsWindRanges(parseIfsIndex(index.toString()));
   const [uBuffer, vBuffer] = await Promise.all([
@@ -112,9 +134,10 @@ export async function fetchIfsWind({
     dx: targetDx,
     dy: targetDx,
   });
-  const runIso = `${cycle.date.slice(0, 4)}-${cycle.date.slice(4, 6)}-${cycle.date.slice(6)}T${String(cycle.hour).padStart(2, '0')}:00:00.000Z`;
+  const runIso = new Date(runMs).toISOString();
+  const validIso = new Date(runMs + forecastHour * 3600_000).toISOString();
   return {
-    cycle: { ...cycle, forecastHour: 0, runIso },
+    cycle: { ...cycle, forecastHour, runIso, validIso },
     level: '10 m above ground',
     units: 'm/s',
     grid,