WeatherBlend

Multi-model forecast blending for Sennen, Cornwall

Rain models

Per-station P(wet ≥ 0.1 mm/h) — 3a (lean) + 3c (rich), Brier, lower better. Plus per-station rainfall amount (mm/h) — 3f distributional, CRPS, lower better. Δ vs best single NWP — negative = blend wins.

Precipitation — Trengwainton

Phase 3c · v2026-08-02_153656_phase3c Δ -0.004 vs prev train

Rich P(wet) classifier, 101 features — rich surface (humidity/dew-depression/cloud/EA persistence) + the multi-level pressure (upper-air) block (850/700/500 hPa temps, heights, winds, RH850 across 4 exact NWPs, lead-matched by a leak-free backward ASOF). UA added in-place 2026-06-02 (−3.7%→−6.8% Brier across 24→72h). Trained 2026-08-02. Metric: Test Brier.

Lead Blend Best single Δ vs best
+24h 0.058 precip_mf (0.087) -33.5%
+48h 0.061 precip_ukmo (0.147) -58.2%
+72h 0.065 precip_ukmo (0.166) -61.0%
+96h 0.070 precip_ukmo (0.181) -61.4%
+120h 0.075 precip_gfs (0.128) -41.1%
Verify history (3 runs)

Mon + Thu rolling Brier. Per-lead cells turn red when the rolling metric breaches the lead-specific drift threshold; check the verify report for the per-cell breakdown. Version column names the trained model — a fresh champion takes ~5-9d to show.

Run (UTC) Version N +12h+24h+48h+72h+96h+120h
v2026-06-10_180531_phase3c
v2026-06-14_153521_phase3c
v2026-06-15_170358_phase3c		 304 0.176
gem: 0.200		0.218
gfs: 0.250		0.231
mf: 0.400		0.245
jma: 0.200		0.095
gem: 0.105		0.151
mf: 0.153
v2026-06-07_145406_phase3c
v2026-06-10_180531_phase3c		 304 0.078
ecmwf: 0.092		0.073
ecmwf: 0.096		0.082
ecmwf: 0.095		0.102
gfs: 0.100		0.089
gem: 0.119		0.071
gfs: 0.091
v2026-06-07_145406_phase3c
v2026-06-10_180531_phase3c		 192 0.330
mf: 0.300		0.157
ecmwf: 0.245		0.223
ukmo: 0.295		0.402
jma: 0.300		——

Phase 3a · v2026-08-02_153533 Δ -0.005 vs prev train

Lean P(wet) classifier, 27 features. Trained 2026-08-02. Metric: Test Brier.

Lead Blend Best single Δ vs best
+24h 0.058 precip_mf (0.087) -32.5%
+48h 0.061 precip_icon (0.121) -49.3%
+72h 0.065 precip_icon (0.126) -48.8%
+96h 0.071 precip_icon (0.159) -55.7%
+120h 0.075 precip_gfs (0.128) -40.9%
Verify history (3 runs)

Mon + Thu rolling Brier. Per-lead cells turn red when the rolling metric breaches the lead-specific drift threshold; check the verify report for the per-cell breakdown. Version column names the trained model — a fresh champion takes ~5-9d to show.

Run (UTC) Version N +24h+48h+72h+96h+120h
v2026-06-07_145307
v2026-06-14_153405		 664 0.152
mf: 0.188		0.214
gem: 0.313		0.230
jma: 0.200		0.070
gem: 0.083		0.072
gem: 0.085
v2026-06-07_145307 566 0.113
ecmwf: 0.163		0.115
gem: 0.173		0.109
mf: 0.140		0.095
gem: 0.119		0.075
gfs: 0.091
v2026-06-07_145307 192 0.157
ecmwf: 0.245		0.221
gem: 0.318		0.402
jma: 0.300		——

Precipitation — Lands End

Phase 3c · v2026-08-02_153713_phase3c Δ -0.002 vs prev train

Rich P(wet) classifier, 101 features — rich surface (humidity/dew-depression/cloud/EA persistence) + the multi-level pressure (upper-air) block (850/700/500 hPa temps, heights, winds, RH850 across 4 exact NWPs, lead-matched by a leak-free backward ASOF). UA added in-place 2026-06-02 (−3.7%→−6.8% Brier across 24→72h). Trained 2026-08-02. Metric: Test Brier.

Lead Blend Best single Δ vs best
+24h 0.060 precip_mf (0.098) -38.2%
+48h 0.064 precip_ukmo (0.213) -70.0%
+72h 0.070 precip_ukmo (0.232) -69.8%
+96h 0.075 precip_ukmo (0.281) -73.2%
+120h 0.076 precip_ukmo (0.314) -75.7%
Verify history (no runs yet)

No verify rows yet for phase 3c. Next cycle: Mon/Thu 09:30 UTC, then 5d ERA5 latency.

Phase 3a · v2026-08-02_153604 Δ -0.003 vs prev train

Lean P(wet) classifier, 27 features. Trained 2026-08-02. Metric: Test Brier.

Lead Blend Best single Δ vs best
+24h 0.060 precip_mf (0.098) -38.3%
+48h 0.065 precip_icon (0.167) -60.9%
+72h 0.070 precip_icon (0.164) -57.7%
+96h 0.074 precip_icon (0.202) -63.4%
+120h 0.076 precip_gfs (0.153) -50.5%
Verify history (no runs yet)

No verify rows yet for phase 3a. Next cycle: Mon/Thu 09:30 UTC, then 5d ERA5 latency.