WPC ERO: drop the Day 3 Excessive Rainfall Outlook check

CHANGELOG.md

@@ -3,6 +3,12 @@
 Notable changes to NwsAlertBot, most recent first. For setup and usage, see
 [README.md](README.md); for architecture and internals, see [docs/TECHNICAL.md](docs/TECHNICAL.md).
 
+- **WPC ERO: dropped the Day 3 Excessive Rainfall Outlook check.** `WpcEroService` now only
+  checks Day 1 and Day 2 against WPC's categorical risk feeds — Day 3's outlook is low-confidence
+  enough that it was producing noisy, low-value alerts. `WPC Day 3 Excessive Rainfall Outlook`
+  will no longer be posted. See docs/TECHNICAL.md "WPC Excessive Rainfall Outlook (ERO) — How It
+  Works".
+
 - **HWO: skip posting all-clear issuances.** New `Hwo.SkipIfNoHazards` setting (default `true`)
   suppresses a Hazardous Weather Outlook issuance when both its `.DAY ONE...` and
   `.DAYS TWO THROUGH SEVEN...` sections report "No hazardous weather is expected at this time" —

Config/AppSettings.cs

@@ -668,16 +668,16 @@ public class EroSettings
 {
     /// <summary>
     /// Whether to monitor the WPC (Weather Prediction Center) Excessive Rainfall Outlook (ERO)
-    /// Day 1/2/3 categorical risk for the locations derived from Location.Zones (or
+    /// Day 1/2 categorical risk for the locations derived from Location.Zones (or
     /// Location.Counties if Zones is empty). Alerts when a monitored location is in any
-    /// non-"None" categorical risk (Marginal or higher) on any of the three days. Note: despite
+    /// non-"None" categorical risk (Marginal or higher) on either day. Note: despite
     /// the "Spc"-prefixed sibling settings (Spc, SpcMcd), ERO is issued by WPC, not SPC.
     /// </summary>
     public bool Enabled { get; set; } = false;
 
     /// <summary>
     /// Minimum seconds between checks against the WPC ERO GeoJSON feeds. WPC re-issues Day 1
-    /// several times a day and Day 2/3 less often, so polling more than every few minutes has
+    /// several times a day and Day 2 less often, so polling more than every few minutes has
     /// no benefit. Default 1800 (30 min) — matches Spc.CheckIntervalSeconds.
     /// </summary>
     public int CheckIntervalSeconds { get; set; } = 1800;

README.md

@@ -592,7 +592,7 @@ and per-platform severity-mapping tables for each are in docs/TECHNICAL.md, link
 | **SPC Convective Outlook** | Day 1/2 severe thunderstorm risk (tornado/wind/hail %) for your area | `"Spc": { "Enabled": true, "CheckIntervalSeconds": 1800 }` | [docs/TECHNICAL.md](docs/TECHNICAL.md#spc-convective-outlook-monitoring--how-it-works) |
 | **SPC Mesoscale Discussion (MCD)** | Short-fuse (1–3h) severe weather potential, ahead of/alongside active watches | `"SpcMcd": { "Enabled": true, "CheckIntervalSeconds": 300 }` | [docs/TECHNICAL.md](docs/TECHNICAL.md#spc-mesoscale-discussion-monitoring--how-it-works) |
 | **Hazardous Weather Outlook (HWO)** | Plain-text 7-day hazard summary from your local NWS office | `"Hwo": { "Enabled": true, "CheckIntervalSeconds": 300 }` | [docs/TECHNICAL.md](docs/TECHNICAL.md#hazardous-weather-outlook-hwo--how-it-works) |
-| **WPC Excessive Rainfall Outlook (ERO)** | Day 1/2/3 flash-flood-guidance-exceedance risk | `"Ero": { "Enabled": true, "CheckIntervalSeconds": 1800 }` | [docs/TECHNICAL.md](docs/TECHNICAL.md#wpc-excessive-rainfall-outlook-ero--how-it-works) |
+| **WPC Excessive Rainfall Outlook (ERO)** | Day 1/2 flash-flood-guidance-exceedance risk | `"Ero": { "Enabled": true, "CheckIntervalSeconds": 1800 }` | [docs/TECHNICAL.md](docs/TECHNICAL.md#wpc-excessive-rainfall-outlook-ero--how-it-works) |
 
 HWO is long-form text (no map image) intended primarily for personal use — its per-platform flag,
 `IncludeHwo`, defaults to `false` (opt-in) rather than `true` like the other three. A common setup

Services/WpcEroService.cs

@@ -7,7 +7,7 @@
 namespace NwsAlertBot.Services;
 
 /// <summary>
-/// Polls the WPC (Weather Prediction Center) Excessive Rainfall Outlook (ERO) Day 1/2/3 GeoJSON
+/// Polls the WPC (Weather Prediction Center) Excessive Rainfall Outlook (ERO) Day 1/2 GeoJSON
 /// feeds and checks each monitored location (derived from Location.Zones/Location.Counties)
 /// against the categorical risk polygons (Marginal/Slight/Moderate/High). Produces one synthetic
 /// NwsAlert per day that is in any non-"None" categorical risk, with a categorical outlook map
@@ -64,7 +64,7 @@ private static TimeZoneInfo ResolveTimeZone(string id, ILogger logger)
 
     /// <summary>
     /// Returns synthetic alerts for every monitored location currently in a non-"None"
-    /// categorical ERO risk on Day 1, 2, or 3. Returns an empty list (no HTTP calls) if
+    /// categorical ERO risk on Day 1 or 2. Returns an empty list (no HTTP calls) if
     /// called before CheckIntervalSeconds has elapsed since the last check.
     /// </summary>
     public async Task<List<NwsAlert>> GetEroAlertsAsync()
@@ -83,7 +83,7 @@ public async Task<List<NwsAlert>> GetEroAlertsAsync()
         }
 
         var results = new List<NwsAlert>();
-        foreach (var day in new[] { 1, 2, 3 })
+        foreach (var day in new[] { 1, 2 })
         {
             var alert = await CheckDayAsync(day, locations);
             if (alert != null) results.Add(alert);

docs/TECHNICAL.md

@@ -430,7 +430,7 @@ Per-platform delivery is controlled by the separate `IncludeHwo` flag, which def
 
 | Field | Description | Default |
 |---|---|---|
-| `Enabled` | Whether to monitor the WPC Excessive Rainfall Outlook Day 1/2/3 categorical risk | `false` |
+| `Enabled` | Whether to monitor the WPC Excessive Rainfall Outlook Day 1/2 categorical risk | `false` |
 | `CheckIntervalSeconds` | Minimum seconds between ERO checks | `1800` |
 
 Per-platform delivery is controlled by the separate `IncludeEro` flag (default `true`).
@@ -594,17 +594,18 @@ The event name for `EventTypes` filtering is `Hazardous Weather Outlook`.
 ## WPC Excessive Rainfall Outlook (ERO) — How It Works
 
 The bot can also monitor the [WPC (Weather Prediction Center) Excessive Rainfall Outlook](https://www.wpc.ncep.noaa.gov/qpf/excessive_rainfall_outlook_ero.php)
-(ERO) — Day 1, 2, and 3 forecasts of the probability that rainfall will exceed flash flood
+(ERO) — Day 1 and 2 forecasts of the probability that rainfall will exceed flash flood
 guidance near a point, categorized into four risk levels: Marginal (≥5%), Slight (≥15%),
 Moderate (≥40%), and High (≥70%). Note: despite living alongside the SPC-issued feeds in this
-bot, ERO is a **WPC** product, not SPC.
+bot, ERO is a **WPC** product, not SPC. Day 3 is intentionally not checked — WPC's Day 3
+outlook is low-confidence enough that it produced noisy, low-value alerts in practice.
 
 - **Locations monitored** reuse the same `Location.Zones`/`Location.Counties` centroids as
   SPC Outlook/MCD — resolved once at startup and cached for the life of the process.
 - **Categorical risk** (`Marginal` / `Slight` / `Moderate` / `High`) is checked independently
-  for Day 1, 2, and 3 against WPC's GeoJSON feeds
-  (`https://www.wpc.ncep.noaa.gov/exper/eromap/geojson/Day{1,2,3}_Latest.geojson`). A location
-  with no categorical match ("None"/sub-5%) never triggers an alert, on any day.
+  for Day 1 and 2 against WPC's GeoJSON feeds
+  (`https://www.wpc.ncep.noaa.gov/exper/eromap/geojson/Day{1,2}_Latest.geojson`). A location
+  with no categorical match ("None"/sub-5%) never triggers an alert, on either day.
 - **Checked every `Ero.CheckIntervalSeconds`** (default 1800s = 30 min) — independent of
   `Polling.PollIntervalSeconds`.
 - **Re-alerts on every new WPC issuance**, not only on a category change, the same as SPC
@@ -626,8 +627,7 @@ bot, ERO is a **WPC** product, not SPC.
 ERO alerts flow through each platform's existing `MinSeverity`/`EventTypes` dials — no new
 filter fields were added beyond `IncludeEro` (see [Configuration Reference](#configuration-reference)):
 
-- **Event names** — `WPC Day 1 Excessive Rainfall Outlook`, `WPC Day 2 Excessive Rainfall Outlook`,
-  and `WPC Day 3 Excessive Rainfall Outlook`.
+- **Event names** — `WPC Day 1 Excessive Rainfall Outlook` and `WPC Day 2 Excessive Rainfall Outlook`.
 - **Severity mapping** — WPC's own category names don't line up 1:1 in name with this bot's
   Severity scale, only in rank order: