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

Seattle-Tacoma · ECMWF AIFS Single · lead day 6

KSEA · aifs_single · lead 6

Target day = initialization date + 6 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
tmax00Zbilinear30d24 1 QC5.48 [3.55, 7.53]3.46-4.86 [-7.47, -2.25]6.56 [4.08, 8.66]0% [0%, 0%]25%33%-0.06+0.332026-08-07 → 2026-08-30
tmax00Zbilinear90d24 1 QC5.48 [3.32, 7.75]3.46-4.86 [-7.60, -1.92]6.56 [3.77, 8.79]0% [0%, 0%]25%33%-0.06+0.332026-08-07 → 2026-08-30
tmax00Zbilinear365d24 1 QC5.48 [3.19, 8.14]3.46-4.86 [-7.95, -1.75]6.56 [3.70, 9.08]0% [0%, 0%]25%33%-0.06+0.332026-08-07 → 2026-08-30
tmax00Zbilinearall24 1 QC5.48 [3.25, 7.83]3.46-4.86 [-7.83, -1.79]6.56 [3.70, 8.89]0% [0%, 0%]25%33%-0.06+0.332026-08-07 → 2026-08-30
tmax00Znearest30d24 1 QC5.24 [3.33, 7.23]3.50-4.54 [-7.17, -1.91]6.36 [3.91, 8.43]0% [0%, 0%]21%38%-0.01+0.322026-08-07 → 2026-08-30
tmax00Znearest90d24 1 QC5.24 [3.13, 7.48]3.50-4.54 [-7.31, -1.55]6.36 [3.60, 8.53]0% [0%, 0%]21%38%-0.01+0.322026-08-07 → 2026-08-30
tmax00Znearest365d24 1 QC5.24 [3.03, 7.85]3.50-4.54 [-7.64, -1.45]6.36 [3.53, 8.86]0% [0%, 0%]21%38%-0.01+0.322026-08-07 → 2026-08-30
tmax00Znearestall24 1 QC5.24 [3.04, 7.52]3.50-4.54 [-7.52, -1.46]6.36 [3.53, 8.65]0% [0%, 0%]21%38%-0.01+0.322026-08-07 → 2026-08-30
tmax12Zbilinear30d24 1 QC4.90 [2.81, 7.00]2.98-4.65 [-6.97, -2.23]5.89 [3.48, 7.70]12% [0%, 36%]25%33%+0.05+0.422026-08-07 → 2026-08-30
tmax12Zbilinear90d24 1 QC4.90 [2.63, 7.24]2.98-4.65 [-7.21, -1.90]5.89 [3.28, 7.96]12% [0%, 43%]25%33%+0.05+0.422026-08-07 → 2026-08-30
tmax12Zbilinear365d24 1 QC4.90 [2.60, 7.64]2.98-4.65 [-7.64, -1.79]5.89 [3.27, 8.18]12% [0%, 43%]25%33%+0.05+0.422026-08-07 → 2026-08-30
tmax12Zbilinearall24 1 QC4.90 [2.59, 7.44]2.98-4.65 [-7.43, -1.89]5.89 [3.26, 8.03]12% [0%, 50%]25%33%+0.05+0.422026-08-07 → 2026-08-30
tmax12Znearest30d24 1 QC4.66 [2.64, 6.73]3.04-4.35 [-6.69, -1.91]5.68 [3.30, 7.47]12% [3%, 29%]21%33%+0.10+0.412026-08-07 → 2026-08-30
tmax12Znearest90d24 1 QC4.66 [2.45, 7.00]3.04-4.35 [-6.93, -1.56]5.68 [3.12, 7.74]12% [0%, 33%]21%33%+0.10+0.412026-08-07 → 2026-08-30
tmax12Znearest365d24 1 QC4.66 [2.46, 7.36]3.04-4.35 [-7.36, -1.48]5.68 [3.12, 7.98]12% [0%, 33%]21%33%+0.10+0.412026-08-07 → 2026-08-30
tmax12Znearestall24 1 QC4.66 [2.45, 7.17]3.04-4.35 [-7.17, -1.55]5.68 [3.08, 7.80]12% [0%, 40%]21%33%+0.10+0.412026-08-07 → 2026-08-30
tmin00Zbilinear30d24 1 QC1.43 [0.96, 1.78]1.45+0.34 [-0.49, 1.10]1.77 [1.34, 2.12]38% [20%, 62%]75%92%+0.34+0.332026-08-07 → 2026-08-30
tmin00Zbilinear90d24 1 QC1.43 [0.84, 1.82]1.45+0.34 [-0.67, 1.17]1.77 [1.24, 2.15]38% [17%, 73%]75%92%+0.34+0.332026-08-07 → 2026-08-30
tmin00Zbilinear365d24 1 QC1.43 [0.86, 1.84]1.45+0.34 [-0.72, 1.21]1.77 [1.19, 2.18]38% [17%, 73%]75%92%+0.34+0.332026-08-07 → 2026-08-30
tmin00Zbilinearall24 1 QC1.43 [0.78, 1.84]1.45+0.34 [-0.70, 1.17]1.77 [1.15, 2.16]38% [16%, 78%]75%92%+0.34+0.332026-08-07 → 2026-08-30
tmin00Znearest30d24 1 QC1.47 [1.02, 1.77]1.47+0.41 [-0.37, 1.11]1.78 [1.36, 2.08]33% [17%, 62%]67%96%+0.32+0.322026-08-07 → 2026-08-30
tmin00Znearest90d24 1 QC1.47 [0.86, 1.81]1.47+0.41 [-0.52, 1.16]1.78 [1.23, 2.11]33% [14%, 73%]67%96%+0.32+0.322026-08-07 → 2026-08-30
tmin00Znearest365d24 1 QC1.47 [0.85, 1.82]1.47+0.41 [-0.56, 1.20]1.78 [1.19, 2.10]33% [14%, 73%]67%96%+0.32+0.322026-08-07 → 2026-08-30
tmin00Znearestall24 1 QC1.47 [0.82, 1.83]1.47+0.41 [-0.57, 1.20]1.78 [1.08, 2.12]33% [14%, 78%]67%96%+0.32+0.322026-08-07 → 2026-08-30
tmin12Zbilinear30d24 1 QC1.34 [1.15, 1.50]1.35+0.25 [-0.55, 1.02]1.53 [1.28, 1.71]33% [17%, 47%]83%100%+0.38+0.382026-08-07 → 2026-08-30
tmin12Zbilinear90d24 1 QC1.34 [1.15, 1.52]1.35+0.25 [-0.72, 1.17]1.53 [1.25, 1.73]33% [14%, 48%]83%100%+0.38+0.382026-08-07 → 2026-08-30
tmin12Zbilinear365d24 1 QC1.34 [1.13, 1.51]1.35+0.25 [-0.77, 1.13]1.53 [1.17, 1.73]33% [14%, 50%]83%100%+0.38+0.382026-08-07 → 2026-08-30
tmin12Zbilinearall24 1 QC1.34 [1.11, 1.52]1.35+0.25 [-0.76, 1.16]1.53 [1.16, 1.73]33% [14%, 48%]83%100%+0.38+0.382026-08-07 → 2026-08-30
tmin12Znearest30d24 1 QC1.33 [1.15, 1.48]1.34+0.30 [-0.46, 1.01]1.53 [1.30, 1.71]42% [32%, 56%]79%96%+0.39+0.382026-08-07 → 2026-08-30
tmin12Znearest90d24 1 QC1.33 [1.13, 1.49]1.34+0.30 [-0.57, 1.10]1.53 [1.27, 1.72]42% [32%, 58%]79%96%+0.39+0.382026-08-07 → 2026-08-30
tmin12Znearest365d24 1 QC1.33 [1.12, 1.49]1.34+0.30 [-0.59, 1.10]1.53 [1.24, 1.72]42% [32%, 58%]79%96%+0.39+0.382026-08-07 → 2026-08-30
tmin12Znearestall24 1 QC1.33 [1.09, 1.49]1.34+0.30 [-0.62, 1.10]1.53 [1.20, 1.73]42% [32%, 61%]79%96%+0.39+0.382026-08-07 → 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 6, 00Z bilinear tmax+20+100-10-202026-08-07: -3.83 °F2026-08-08: -6.48 °F2026-08-09: -1.93 °F2026-08-10: +5.95 °F2026-08-11: -2.48 °F2026-08-12: -6.42 °F2026-08-13: -1.84 °F2026-08-14: +1.54 °F2026-08-15: -1.86 °F2026-08-16: -1.38 °F2026-08-17: -7.36 °F2026-08-18: -10.39 °F2026-08-19: -14.37 °F2026-08-20: -13.34 °F2026-08-21: -3.02 °F2026-08-22: -8.53 °F2026-08-23: -6.66 °F2026-08-24: -7.42 °F2026-08-25: -9.08 °F2026-08-26: -4.02 °F2026-08-27: -4.87 °F2026-08-28: -4.27 °F2026-08-29: -2.95 °F2026-08-30: -1.52 °F2026-08-072026-08-30°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 (24 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-1.52
2026-08-29-2.95
2026-08-28-4.27
2026-08-27-4.87
2026-08-26-4.02
2026-08-25-9.08
2026-08-24-7.42
2026-08-23-6.66
2026-08-22-8.53
2026-08-21-3.02
2026-08-20-13.34
2026-08-19-14.37
2026-08-18-10.39
2026-08-17-7.36
2026-08-16-1.38
2026-08-15-1.86
2026-08-14+1.54
2026-08-13-1.84
2026-08-12-6.42
2026-08-11-2.48
2026-08-10+5.95
2026-08-09-1.93
2026-08-08-6.48
2026-08-07-3.83

Error distribution

Distribution of the signed daily error in °F for ECMWF AIFS Single at KSEA, lead day 6-20 to -18 °F: 0 days-18 to -16 °F: 0 days-16 to -14 °F: 1 day-14 to -12 °F: 1 day-12 to -10 °F: 1 day-10 to -8 °F: 2 days-8 to -6 °F: 5 days-6 to -4 °F: 3 days-4 to -2 °F: 4 days-2 to 0 °F: 5 days0 to 2 °F: 1 day2 to 4 °F: 0 days4 to 6 °F: 1 day6 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| 4.57 · P90 |e| 10 °F-200+20 °Fn = 24 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
-16.00-14.001
-14.00-12.001
-12.00-10.001
-10.00-8.002
-8.00-6.005
-6.00-4.003
-4.00-2.004
-2.00+0.005
+0.00+2.001
+2.00+4.000
+4.00+6.001
+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
2026-08245.48 -4.86

Availability

ModelScored period DaysCoverage
ECMWF AIFS Single2026-08-07 → 2026-08-30 24
ECMWF AIFS Single2026-08-07 → 2026-08-30 24
ECMWF AIFS Single2026-08-07 → 2026-08-30 24
ECMWF AIFS Single2026-08-07 → 2026-08-30 24

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 24 +0.63 [-2.80, 3.65] no
GraphCast (IFS init) 24 -1.20 [-2.59, -0.43] yes
ECMWF IFS HRES 19 +0.95 [-2.30, 2.34] no
Persistence (baseline) 24 +0.31 [-4.45, 3.87] no

Cite this page

ShortCastCheck, KSEA aifs_single lead 6, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KSEA/model/aifs_single/lead/6/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KSEA (Seattle-Tacoma), model aifs_single, lead day 6. 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/6/

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