Fix a bug in the GeoJSON handling when there are no active polygons

internal/normalizers/spc/convective_outlook.go

@@ -87,6 +87,17 @@ func buildConvectiveOutlook(bundle spcprovider.RawConvectiveOutlookBundle, fallb
 		}
 
 		for i, feature := range collection.Features {
+			if spcprovider.IsEmptyGeometryCollection(feature.Geometry) {
+				issuedAt, err := parseRequiredSPCTime(feature.Properties.IssueISO, fmt.Sprintf("product %s feature %d.ISSUE_ISO", product.Key, i))
+				if err != nil {
+					return model.WeatherOutlookRun{}, time.Time{}, err
+				}
+				if latestIssue.IsZero() || issuedAt.After(latestIssue) {
+					latestIssue = issuedAt
+				}
+				continue
+			}
+
 			outlook, err := mapFeature(product, feature, i, point, discussion)
 			if err != nil {
 				return model.WeatherOutlookRun{}, time.Time{}, err

internal/normalizers/spc/convective_outlook_test.go

@@ -167,6 +167,39 @@ func TestConvectiveOutlookNormalizerMapsProbabilisticOutlookTypes(t *testing.T)
 	}
 }
 
+func TestConvectiveOutlookNormalizerSkipsEmptyGeometryCollectionPlaceholder(t *testing.T) {
+	bundle := spcBundle(t, 0, 0)
+	replaced := false
+	for i := range bundle.Products {
+		if bundle.Products[i].Day == 2 && bundle.Products[i].OutlookType == spcprovider.OutlookTypeTornado {
+			bundle.Products[i].Body = json.RawMessage(emptyGeometryCollectionGeoJSON())
+			replaced = true
+		}
+	}
+	if !replaced {
+		t.Fatalf("test setup did not find day 2 tornado product")
+	}
+
+	out, err := (ConvectiveOutlookNormalizer{}).Normalize(nil, spcRawEvent(t, bundle))
+	if err != nil {
+		t.Fatalf("Normalize() error = %v", err)
+	}
+	run := out.Payload.(model.WeatherOutlookRun)
+	if len(run.Outlooks) != 8 {
+		t.Fatalf("Outlooks length = %d, want 8", len(run.Outlooks))
+	}
+	if got := findOutlook(run.Outlooks, 2, spcprovider.OutlookTypeTornado); got != nil {
+		t.Fatalf("day 2 tornado outlook = %+v, want nil placeholder skipped", *got)
+	}
+	wantAsOf := time.Date(2026, 6, 12, 10, 0, 0, 0, time.UTC)
+	if !run.AsOf.Equal(wantAsOf) {
+		t.Fatalf("AsOf = %s, want placeholder ISSUE_ISO %s", run.AsOf, wantAsOf)
+	}
+	if out.EffectiveAt == nil || !out.EffectiveAt.Equal(wantAsOf) {
+		t.Fatalf("EffectiveAt = %v, want placeholder ISSUE_ISO %s", out.EffectiveAt, wantAsOf)
+	}
+}
+
 func TestConvectiveOutlookNormalizerContainsLocationFalseOutsidePolygon(t *testing.T) {
 	out, err := (ConvectiveOutlookNormalizer{}).Normalize(nil, spcRawEvent(t, spcBundle(t, 0, 0)))
 	if err != nil {
@@ -280,6 +313,30 @@ func TestConvectiveOutlookNormalizerOutputJSONShape(t *testing.T) {
 	}
 }
 
+func emptyGeometryCollectionGeoJSON() []byte {
+	return []byte(`{
+  "type": "FeatureCollection",
+  "features": [
+    {
+      "type": "Feature",
+      "properties": {
+        "VALID_ISO": "2026-06-12T12:00:00Z",
+        "EXPIRE_ISO": "2026-06-13T12:00:00Z",
+        "ISSUE_ISO": "2026-06-12T10:00:00Z",
+        "FORECASTER": "DOE",
+        "LABEL": "Less Than 2% All Areas",
+        "LABEL2": "",
+        "DN": 0
+      },
+      "geometry": {
+        "type": "GeometryCollection",
+        "geometries": []
+      }
+    }
+  ]
+}`)
+}
+
 func spcRawEvent(t *testing.T, bundle spcprovider.RawConvectiveOutlookBundle) event.Event {
 	t.Helper()
 	raw, err := json.Marshal(bundle)

internal/providers/spc/geojson.go

@@ -33,6 +33,11 @@ type GeoJSONProperties struct {
 	DN         *int   `json:"DN"`
 }
 
+type geometryMetadata struct {
+	Type       string            `json:"type"`
+	Geometries []json.RawMessage `json:"geometries"`
+}
+
 // DecodeGeoJSON decodes an SPC GeoJSON outlook product and compacts feature
 // geometry JSON for stable downstream storage.
 func DecodeGeoJSON(raw []byte) (GeoJSONFeatureCollection, error) {
@@ -50,6 +55,16 @@ func DecodeGeoJSON(raw []byte) (GeoJSONFeatureCollection, error) {
 	return collection, nil
 }
 
+// IsEmptyGeometryCollection reports whether raw is SPC's no-polygon placeholder
+// geometry shape: a GeometryCollection with no child geometries.
+func IsEmptyGeometryCollection(raw json.RawMessage) bool {
+	var meta geometryMetadata
+	if err := json.Unmarshal(raw, &meta); err != nil {
+		return false
+	}
+	return meta.Type == "GeometryCollection" && len(meta.Geometries) == 0
+}
+
 func (p *GeoJSONProperties) UnmarshalJSON(raw []byte) error {
 	type alias GeoJSONProperties
 	var aux struct {

internal/providers/spc/geojson_test.go

@@ -66,6 +66,43 @@ func TestDecodeGeoJSONParsesSeverityRankString(t *testing.T) {
 	}
 }
 
+func TestIsEmptyGeometryCollection(t *testing.T) {
+	tests := []struct {
+		name string
+		raw  string
+		want bool
+	}{
+		{
+			name: "empty geometry collection",
+			raw:  `{"type":"GeometryCollection","geometries":[]}`,
+			want: true,
+		},
+		{
+			name: "non-empty geometry collection",
+			raw:  `{"type":"GeometryCollection","geometries":[{"type":"Polygon","coordinates":[]} ]}`,
+			want: false,
+		},
+		{
+			name: "polygon",
+			raw:  `{"type":"Polygon","coordinates":[]}`,
+			want: false,
+		},
+		{
+			name: "invalid json",
+			raw:  `{`,
+			want: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := IsEmptyGeometryCollection([]byte(tt.raw)); got != tt.want {
+				t.Fatalf("IsEmptyGeometryCollection() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
 func TestParseISOTimestampTrimsAndReturnsUTC(t *testing.T) {
 	got, err := ParseISOTimestamp(" 2026-06-11T12:34:56Z ")
 	if err != nil {