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CastCheck methodology v0.2 · data through 2026-08-30

Seattle-Tacoma · ECMWF AIFS Single · lead day 4

KSEA · aifs_single · lead 4

Target day = initialization date + 4 days. This page is a permanent link: the numbers change as history accumulates, the address and the methodology version do not.

Scores use the latest model version segment, aifs-single-gpid5, starting 2026-08-01 — days before that ran a different version of the model and are excluded rather than silently pooled. Of the scored days, 1 carry a QC flag on the observation.

JSON for this page CSV of the daily errors Cite this page

Every number for this combination

All four windows × both initializations × both interpolations × both variables. Errors are computed in °C and shown in °F; CI is a 95 % moving-block bootstrap interval. MAE debiased and skill, debiased remove the constant offset of the window first, so a station that the model always reads a degree too warm is not scored as if it had no skill — compare the two skill columns to see how much of the error is a fixed offset. n QC next to n counts days whose observation carries a QC flag.

VariableInitMethod Windown MAE °F MAE debiased Bias °F RMSE °F ±1 °F±2 °F±3 °F Skill Skill, debiased Period
tmax00Zbilinear30d26 1 QC4.75 [3.35, 6.27]2.03-4.75 [-6.27, -3.35]5.39 [3.78, 6.90]8% [0%, 18%]12%23%+0.26+0.682026-08-05 → 2026-08-30
tmax00Zbilinear90d26 1 QC4.75 [3.29, 6.40]2.03-4.75 [-6.40, -3.29]5.39 [3.71, 6.98]8% [0%, 22%]12%23%+0.26+0.682026-08-05 → 2026-08-30
tmax00Zbilinear365d26 1 QC4.75 [3.23, 6.56]2.03-4.75 [-6.56, -3.23]5.39 [3.67, 7.14]8% [0%, 22%]12%23%+0.26+0.682026-08-05 → 2026-08-30
tmax00Zbilinearall26 1 QC4.75 [3.20, 6.47]2.03-4.75 [-6.47, -3.20]5.39 [3.60, 7.07]8% [0%, 22%]12%23%+0.26+0.682026-08-05 → 2026-08-30
tmax00Znearest30d26 1 QC4.42 [2.99, 5.99]2.04-4.42 [-5.99, -2.99]5.12 [3.45, 6.69]8% [0%, 18%]12%35%+0.32+0.682026-08-05 → 2026-08-30
tmax00Znearest90d26 1 QC4.42 [2.93, 6.11]2.04-4.42 [-6.11, -2.93]5.12 [3.39, 6.77]8% [0%, 22%]12%35%+0.32+0.682026-08-05 → 2026-08-30
tmax00Znearest365d26 1 QC4.42 [2.90, 6.27]2.04-4.42 [-6.27, -2.90]5.12 [3.36, 6.91]8% [0%, 22%]12%35%+0.32+0.682026-08-05 → 2026-08-30
tmax00Znearestall26 1 QC4.42 [2.86, 6.16]2.04-4.42 [-6.16, -2.86]5.12 [3.31, 6.83]8% [0%, 22%]12%35%+0.32+0.682026-08-05 → 2026-08-30
tmax12Zbilinear30d26 1 QC4.97 [3.66, 6.37]2.03-4.97 [-6.37, -3.66]5.55 [4.03, 6.93]4% [0%, 11%]8%23%+0.23+0.682026-08-05 → 2026-08-30
tmax12Zbilinear90d26 1 QC4.97 [3.58, 6.46]2.03-4.97 [-6.46, -3.58]5.55 [3.93, 7.02]4% [0%, 12%]8%23%+0.23+0.682026-08-05 → 2026-08-30
tmax12Zbilinear365d26 1 QC4.97 [3.57, 6.60]2.03-4.97 [-6.60, -3.57]5.55 [3.88, 7.16]4% [0%, 11%]8%23%+0.23+0.682026-08-05 → 2026-08-30
tmax12Zbilinearall26 1 QC4.97 [3.51, 6.55]2.03-4.97 [-6.55, -3.51]5.55 [3.82, 7.04]4% [0%, 12%]8%23%+0.23+0.682026-08-05 → 2026-08-30
tmax12Znearest30d26 1 QC4.64 [3.31, 6.09]2.04-4.64 [-6.09, -3.31]5.27 [3.70, 6.69]8% [0%, 17%]15%31%+0.28+0.682026-08-05 → 2026-08-30
tmax12Znearest90d26 1 QC4.64 [3.23, 6.19]2.04-4.64 [-6.19, -3.23]5.27 [3.62, 6.78]8% [0%, 17%]15%31%+0.28+0.682026-08-05 → 2026-08-30
tmax12Znearest365d26 1 QC4.64 [3.23, 6.31]2.04-4.64 [-6.31, -3.23]5.27 [3.57, 6.91]8% [0%, 18%]15%31%+0.28+0.682026-08-05 → 2026-08-30
tmax12Znearestall26 1 QC4.64 [3.18, 6.27]2.04-4.64 [-6.27, -3.18]5.27 [3.51, 6.80]8% [0%, 17%]15%31%+0.28+0.682026-08-05 → 2026-08-30
tmin00Zbilinear30d26 1 QC1.11 [0.96, 1.29]1.11-0.21 [-0.81, 0.37]1.30 [1.14, 1.45]50% [35%, 64%]85%100%+0.48+0.482026-08-05 → 2026-08-30
tmin00Zbilinear90d26 1 QC1.11 [0.96, 1.29]1.11-0.21 [-0.89, 0.41]1.30 [1.15, 1.48]50% [33%, 64%]85%100%+0.48+0.482026-08-05 → 2026-08-30
tmin00Zbilinear365d26 1 QC1.11 [0.96, 1.30]1.11-0.21 [-0.93, 0.44]1.30 [1.15, 1.48]50% [33%, 64%]85%100%+0.48+0.482026-08-05 → 2026-08-30
tmin00Zbilinearall26 1 QC1.11 [0.97, 1.33]1.11-0.21 [-1.01, 0.45]1.30 [1.15, 1.50]50% [31%, 64%]85%100%+0.48+0.482026-08-05 → 2026-08-30
tmin00Znearest30d26 1 QC1.13 [0.96, 1.31]1.13-0.15 [-0.76, 0.45]1.34 [1.17, 1.49]46% [35%, 57%]88%100%+0.47+0.472026-08-05 → 2026-08-30
tmin00Znearest90d26 1 QC1.13 [0.96, 1.33]1.13-0.15 [-0.84, 0.49]1.34 [1.18, 1.51]46% [33%, 58%]88%100%+0.47+0.472026-08-05 → 2026-08-30
tmin00Znearest365d26 1 QC1.13 [0.96, 1.34]1.13-0.15 [-0.85, 0.50]1.34 [1.17, 1.51]46% [33%, 58%]88%100%+0.47+0.472026-08-05 → 2026-08-30
tmin00Znearestall26 1 QC1.13 [0.96, 1.36]1.13-0.15 [-0.99, 0.52]1.34 [1.18, 1.53]46% [31%, 57%]88%100%+0.47+0.472026-08-05 → 2026-08-30
tmin12Zbilinear30d26 1 QC1.05 [0.92, 1.23]1.06-0.26 [-0.81, 0.25]1.23 [1.08, 1.43]54% [36%, 70%]96%100%+0.50+0.502026-08-05 → 2026-08-30
tmin12Zbilinear90d26 1 QC1.05 [0.91, 1.25]1.06-0.26 [-0.97, 0.30]1.23 [1.06, 1.45]54% [31%, 71%]96%100%+0.50+0.502026-08-05 → 2026-08-30
tmin12Zbilinear365d26 1 QC1.05 [0.91, 1.23]1.06-0.26 [-0.93, 0.32]1.23 [1.06, 1.43]54% [33%, 71%]96%100%+0.50+0.502026-08-05 → 2026-08-30
tmin12Zbilinearall26 1 QC1.05 [0.91, 1.29]1.06-0.26 [-1.02, 0.30]1.23 [1.06, 1.48]54% [31%, 71%]96%100%+0.50+0.502026-08-05 → 2026-08-30
tmin12Znearest30d26 1 QC1.08 [0.93, 1.24]1.09-0.20 [-0.76, 0.33]1.25 [1.08, 1.45]38% [23%, 57%]92%100%+0.49+0.492026-08-05 → 2026-08-30
tmin12Znearest90d26 1 QC1.08 [0.93, 1.26]1.09-0.20 [-0.87, 0.36]1.25 [1.04, 1.49]38% [23%, 58%]92%100%+0.49+0.492026-08-05 → 2026-08-30
tmin12Znearest365d26 1 QC1.08 [0.92, 1.25]1.09-0.20 [-0.84, 0.38]1.25 [1.03, 1.47]38% [22%, 57%]92%100%+0.49+0.492026-08-05 → 2026-08-30
tmin12Znearestall26 1 QC1.08 [0.94, 1.27]1.09-0.20 [-0.98, 0.37]1.25 [1.04, 1.49]38% [20%, 57%]92%100%+0.49+0.492026-08-05 → 2026-08-30

+ model too warm · − model too cold · bias interval includes zero · ★ lowest MAE · = not distinguishable from the leader · ▼ significantly worse · n < 30 greyed and unranked · CI is a 95 % moving-block bootstrap interval.

Daily error, last 90 days

Daily forecast minus observed error in °F for ECMWF AIFS Single at KSEA, lead day 4, 00Z bilinear tmax+20+100-10-202026-08-05: -3.45 °F2026-08-06: -2.42 °F2026-08-07: -6.08 °F2026-08-08: -3.27 °F2026-08-09: -1.86 °F2026-08-10: -0.55 °F2026-08-11: -4.47 °F2026-08-12: -4.25 °F2026-08-13: -5.36 °F2026-08-14: -5.78 °F2026-08-15: -2.85 °F2026-08-16: -3.19 °F2026-08-17: -4.81 °F2026-08-18: -7.81 °F2026-08-19: -11.24 °F2026-08-20: -9.37 °F2026-08-21: -7.61 °F2026-08-22: -8.18 °F2026-08-23: -3.47 °F2026-08-24: -5.81 °F2026-08-25: -4.82 °F2026-08-26: -3.08 °F2026-08-27: -2.7 °F2026-08-28: -6.55 °F2026-08-29: -3.86 °F2026-08-30: -0.76 °F2026-08-052026-08-30°F, forecast − observed
Forecast − observed, °F, 00Z bilinear daily maximum. The dashed line is zero; the thick line is a centred 7-day mean, drawn only where the whole window is present. Gaps are days with no score, never interpolation. Hover a point for its date and value.
The same series as a table (26 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-0.76
2026-08-29-3.86
2026-08-28-6.55
2026-08-27-2.70
2026-08-26-3.08
2026-08-25-4.82
2026-08-24-5.81
2026-08-23-3.47
2026-08-22-8.18
2026-08-21-7.61
2026-08-20-9.37
2026-08-19-11.24
2026-08-18-7.81
2026-08-17-4.81
2026-08-16-3.19
2026-08-15-2.85
2026-08-14-5.78
2026-08-13-5.36
2026-08-12-4.25
2026-08-11-4.47
2026-08-10-0.55
2026-08-09-1.86
2026-08-08-3.27
2026-08-07-6.08
2026-08-06-2.42
2026-08-05-3.45

Error distribution

Distribution of the signed daily error in °F for ECMWF AIFS Single at KSEA, lead day 4-20 to -18 °F: 0 days-18 to -16 °F: 0 days-16 to -14 °F: 0 days-14 to -12 °F: 0 days-12 to -10 °F: 1 day-10 to -8 °F: 2 days-8 to -6 °F: 4 days-6 to -4 °F: 7 days-4 to -2 °F: 9 days-2 to 0 °F: 3 days0 to 2 °F: 0 days2 to 4 °F: 0 days4 to 6 °F: 0 days6 to 8 °F: 0 days8 to 10 °F: 0 days10 to 12 °F: 0 days12 to 14 °F: 0 days14 to 16 °F: 0 days16 to 18 °F: 0 days18 to 20 °F: 0 daysdashed: P50 |e| 4.36 · P90 |e| 8 °F-200+20 °Fn = 26 days
All scored days for 00Z bilinear daily maximum, 20 equal bins. The dashed marks are the 50th and 90th percentiles of the absolute error, mirrored on both sides. Hover a bar for its bin and count.
Bin counts as a table
From °FTo °FDays
-20.00-18.000
-18.00-16.000
-16.00-14.000
-14.00-12.000
-12.00-10.001
-10.00-8.002
-8.00-6.004
-6.00-4.007
-4.00-2.009
-2.00+0.003
+0.00+2.000
+2.00+4.000
+4.00+6.000
+6.00+8.000
+8.00+10.000
+10.00+12.000
+12.00+14.000
+14.00+16.000
+16.00+18.000
+18.00+20.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08264.75 -4.75

Availability

ModelScored period DaysCoverage
ECMWF AIFS Single2026-08-05 → 2026-08-30 26
ECMWF AIFS Single2026-08-05 → 2026-08-30 26
ECMWF AIFS Single2026-08-05 → 2026-08-30 26
ECMWF AIFS Single2026-08-05 → 2026-08-30 26

Compared with other models

Paired bootstrap on the days both models cover (90d, 00Z, bilinear, daily maximum). Negative means ECMWF AIFS Single has the lower MAE. "Distinguishable" means the 95 % interval excludes zero.

Other modelCommon days MAE difference °FDistinguishable
NCEP GFS 26 +0.32 [-2.18, 3.18] no
GraphCast (IFS init) 25 -0.21 [-0.79, 0.44] no
ECMWF IFS HRES 20 +2.54 [1.76, 3.40] yes
Persistence (baseline) 26 -1.71 [-7.56, 1.50] no

Cite this page

ShortCastCheck, KSEA aifs_single lead 4, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KSEA/model/aifs_single/lead/4/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KSEA (Seattle-Tacoma), model aifs_single, lead day 4. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KSEA/model/aifs_single/lead/4/

Accessed2026-08-31 (data through 2026-08-30; page built 2026-08-31T03:52:06+00:00)

JSON CSV all scores methodology v0.2 licence