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

Seattle-Tacoma · ECMWF AIFS Single · lead day 8

KSEA · aifs_single · lead 8

Target day = initialization date + 8 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
tmax00Zbilinear30d22 1 QC6.39 [3.08, 9.01]4.49-6.25 [-9.01, -2.65]8.19 [4.20, 10.68]5% [0%, 19%]27%27%-0.16+0.182026-08-09 → 2026-08-30
tmax00Zbilinear90d22 1 QC6.39 [2.14, 9.16]4.49-6.25 [-9.06, -1.86]8.19 [2.75, 10.76]5% [0%, 22%]27%27%-0.16+0.182026-08-09 → 2026-08-30
tmax00Zbilinear365d22 1 QC6.39 [2.13, 9.70]4.49-6.25 [-9.70, -1.86]8.19 [2.70, 11.21]5% [0%, 22%]27%27%-0.16+0.182026-08-09 → 2026-08-30
tmax00Zbilinearall22 1 QC6.39 [1.86, 9.28]4.49-6.25 [-9.28, -1.86]8.19 [2.36, 10.94]5% [0%, 26%]27%27%-0.16+0.182026-08-09 → 2026-08-30
tmax00Znearest30d22 1 QC6.11 [2.83, 8.69]4.50-5.94 [-8.69, -2.37]7.98 [4.02, 10.46]14% [0%, 32%]27%27%-0.11+0.182026-08-09 → 2026-08-30
tmax00Znearest90d22 1 QC6.11 [1.92, 8.85]4.50-5.94 [-8.78, -1.60]7.98 [2.56, 10.53]14% [0%, 40%]27%27%-0.11+0.182026-08-09 → 2026-08-30
tmax00Znearest365d22 1 QC6.11 [1.90, 9.38]4.50-5.94 [-9.38, -1.60]7.98 [2.52, 10.96]14% [0%, 38%]27%27%-0.11+0.182026-08-09 → 2026-08-30
tmax00Znearestall22 1 QC6.11 [1.66, 8.98]4.50-5.94 [-8.98, -1.60]7.98 [2.16, 10.69]14% [0%, 44%]27%27%-0.11+0.182026-08-09 → 2026-08-30
tmax12Zbilinear30d22 1 QC5.56 [2.80, 7.32]4.24-4.93 [-6.97, -2.37]7.04 [4.06, 8.68]18% [0%, 50%]23%36%-0.01+0.232026-08-09 → 2026-08-30
tmax12Zbilinear90d22 1 QC5.56 [1.66, 7.39]4.24-4.93 [-7.10, -1.60]7.04 [2.87, 8.80]18% [0%, 62%]23%36%-0.01+0.232026-08-09 → 2026-08-30
tmax12Zbilinear365d22 1 QC5.56 [1.77, 7.72]4.24-4.93 [-7.48, -1.63]7.04 [2.57, 9.05]18% [0%, 62%]23%36%-0.01+0.232026-08-09 → 2026-08-30
tmax12Zbilinearall22 1 QC5.56 [1.30, 7.56]4.24-4.93 [-7.01, -1.21]7.04 [1.81, 8.86]18% [0%, 67%]23%36%-0.01+0.232026-08-09 → 2026-08-30
tmax12Znearest30d22 1 QC5.42 [2.73, 7.14]4.27-4.62 [-6.66, -2.04]6.86 [3.91, 8.47]18% [0%, 50%]27%45%+0.01+0.222026-08-09 → 2026-08-30
tmax12Znearest90d22 1 QC5.42 [1.77, 7.21]4.27-4.62 [-6.79, -1.33]6.86 [2.67, 8.59]18% [0%, 62%]27%45%+0.01+0.222026-08-09 → 2026-08-30
tmax12Znearest365d22 1 QC5.42 [1.71, 7.44]4.27-4.62 [-7.18, -1.34]6.86 [2.35, 8.80]18% [0%, 62%]27%45%+0.01+0.222026-08-09 → 2026-08-30
tmax12Znearestall22 1 QC5.42 [1.30, 7.34]4.27-4.62 [-6.71, -0.96]6.86 [1.65, 8.63]18% [0%, 67%]27%45%+0.01+0.222026-08-09 → 2026-08-30
tmin00Zbilinear30d22 1 QC2.04 [1.63, 2.62]1.97+0.41 [-1.53, 1.84]2.49 [2.01, 3.03]32% [11%, 53%]55%77%+0.08+0.122026-08-09 → 2026-08-30
tmin00Zbilinear90d22 1 QC2.04 [1.58, 2.64]1.97+0.41 [-1.90, 1.99]2.49 [1.95, 3.06]32% [0%, 56%]55%77%+0.08+0.122026-08-09 → 2026-08-30
tmin00Zbilinear365d22 1 QC2.04 [1.59, 2.68]1.97+0.41 [-2.03, 2.03]2.49 [1.92, 3.09]32% [0%, 57%]55%77%+0.08+0.122026-08-09 → 2026-08-30
tmin00Zbilinearall22 1 QC2.04 [1.53, 2.67]1.97+0.41 [-1.88, 1.99]2.49 [1.95, 3.05]32% [4%, 59%]55%77%+0.08+0.122026-08-09 → 2026-08-30
tmin00Znearest30d22 1 QC2.08 [1.68, 2.61]1.96+0.53 [-1.40, 1.96]2.53 [2.05, 3.03]27% [9%, 48%]55%73%+0.06+0.122026-08-09 → 2026-08-30
tmin00Znearest90d22 1 QC2.08 [1.61, 2.61]1.96+0.53 [-1.80, 2.07]2.53 [2.00, 3.04]27% [0%, 50%]55%73%+0.06+0.122026-08-09 → 2026-08-30
tmin00Znearest365d22 1 QC2.08 [1.61, 2.65]1.96+0.53 [-1.94, 2.11]2.53 [1.96, 3.11]27% [0%, 50%]55%73%+0.06+0.122026-08-09 → 2026-08-30
tmin00Znearestall22 1 QC2.08 [1.57, 2.62]1.96+0.53 [-1.78, 2.08]2.53 [2.02, 3.02]27% [3%, 56%]55%73%+0.06+0.122026-08-09 → 2026-08-30
tmin12Zbilinear30d22 1 QC1.89 [1.41, 2.34]1.86+0.29 [-1.47, 1.62]2.53 [1.82, 3.09]36% [24%, 50%]68%77%+0.15+0.172026-08-09 → 2026-08-30
tmin12Zbilinear90d22 1 QC1.89 [1.39, 2.34]1.86+0.29 [-1.75, 1.68]2.53 [1.67, 3.03]36% [22%, 52%]68%77%+0.15+0.172026-08-09 → 2026-08-30
tmin12Zbilinear365d22 1 QC1.89 [1.34, 2.33]1.86+0.29 [-1.83, 1.74]2.53 [1.65, 3.05]36% [22%, 56%]68%77%+0.15+0.172026-08-09 → 2026-08-30
tmin12Zbilinearall22 1 QC1.89 [1.24, 2.34]1.86+0.29 [-1.79, 1.74]2.53 [1.48, 3.04]36% [22%, 56%]68%77%+0.15+0.172026-08-09 → 2026-08-30
tmin12Znearest30d22 1 QC1.96 [1.48, 2.40]1.90+0.35 [-1.48, 1.72]2.59 [1.87, 3.16]36% [18%, 57%]68%73%+0.12+0.152026-08-09 → 2026-08-30
tmin12Znearest90d22 1 QC1.96 [1.47, 2.40]1.90+0.35 [-1.74, 1.77]2.59 [1.78, 3.11]36% [14%, 58%]68%73%+0.12+0.152026-08-09 → 2026-08-30
tmin12Znearest365d22 1 QC1.96 [1.41, 2.41]1.90+0.35 [-1.82, 1.84]2.59 [1.71, 3.13]36% [14%, 60%]68%73%+0.12+0.152026-08-09 → 2026-08-30
tmin12Znearestall22 1 QC1.96 [1.27, 2.41]1.90+0.35 [-1.80, 1.83]2.59 [1.52, 3.12]36% [14%, 67%]68%73%+0.12+0.152026-08-09 → 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 8, 00Z bilinear tmax+20+100-10-202026-08-09: -1.38 °F2026-08-10: +1.56 °F2026-08-11: -1.9 °F2026-08-12: -7.37 °F2026-08-13: -10.91 °F2026-08-14: -3.57 °F2026-08-15: -1.31 °F2026-08-16: -3.48 °F2026-08-17: -9.73 °F2026-08-18: -12.02 °F2026-08-19: -19.92 °F2026-08-20: -13.5 °F2026-08-21: -6.8 °F2026-08-22: -3.73 °F2026-08-23: -3.76 °F2026-08-24: -12.59 °F2026-08-25: -12.75 °F2026-08-26: -3.7 °F2026-08-27: -4.97 °F2026-08-28: -1.29 °F2026-08-29: -3.86 °F2026-08-30: -0.41 °F2026-08-092026-08-30°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 (22 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-0.41
2026-08-29-3.86
2026-08-28-1.29
2026-08-27-4.97
2026-08-26-3.70
2026-08-25-12.75
2026-08-24-12.59
2026-08-23-3.76
2026-08-22-3.73
2026-08-21-6.80
2026-08-20-13.50
2026-08-19-19.92
2026-08-18-12.02
2026-08-17-9.73
2026-08-16-3.48
2026-08-15-1.31
2026-08-14-3.57
2026-08-13-10.91
2026-08-12-7.37
2026-08-11-1.90
2026-08-10+1.56
2026-08-09-1.38

Error distribution

Distribution of the signed daily error in °F for ECMWF AIFS Single at KSEA, lead day 8-20 to -18 °F: 1 day-18 to -16 °F: 0 days-16 to -14 °F: 0 days-14 to -12 °F: 4 days-12 to -10 °F: 1 day-10 to -8 °F: 1 day-8 to -6 °F: 2 days-6 to -4 °F: 1 day-4 to -2 °F: 6 days-2 to 0 °F: 5 days0 to 2 °F: 1 day2 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| 3.81 · P90 |e| 12.74 °F-200+20 °Fn = 22 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
-20.00-18.001
-18.00-16.000
-16.00-14.000
-14.00-12.004
-12.00-10.001
-10.00-8.001
-8.00-6.002
-6.00-4.001
-4.00-2.006
-2.00+0.005
+0.00+2.001
+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
2026-08226.39 -6.25

Availability

ModelScored period DaysCoverage
ECMWF AIFS Single2026-08-09 → 2026-08-30 22
ECMWF AIFS Single2026-08-09 → 2026-08-30 22
ECMWF AIFS Single2026-08-09 → 2026-08-30 22
ECMWF AIFS Single2026-08-09 → 2026-08-30 22

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 22 -0.90 [-3.79, 1.99] no
GraphCast (IFS init) 22 -0.18 [-1.84, 1.92] no
ECMWF IFS HRES 17 +0.64 [-3.30, 2.52] no
Persistence (baseline) 22 +0.89 [-4.71, 4.99] no

Cite this page

ShortCastCheck, KSEA aifs_single lead 8, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KSEA/model/aifs_single/lead/8/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KSEA (Seattle-Tacoma), model aifs_single, lead day 8. 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/8/

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