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

Seattle-Tacoma · ECMWF AIFS Single · lead day 3

KSEA · aifs_single · lead 3

Target day = initialization date + 3 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
tmax00Zbilinear30d27 1 QC5.15 [3.59, 6.77]2.06-5.15 [-6.77, -3.59]5.83 [4.01, 7.47]7% [0%, 18%]11%22%+0.19+0.672026-08-04 → 2026-08-30
tmax00Zbilinear90d27 1 QC5.15 [3.43, 6.98]2.06-5.15 [-6.98, -3.43]5.83 [3.92, 7.60]7% [0%, 20%]11%22%+0.19+0.672026-08-04 → 2026-08-30
tmax00Zbilinear365d27 1 QC5.15 [3.48, 7.05]2.06-5.15 [-7.05, -3.48]5.83 [3.93, 7.66]7% [0%, 21%]11%22%+0.19+0.672026-08-04 → 2026-08-30
tmax00Zbilinearall27 1 QC5.15 [3.34, 7.01]2.06-5.15 [-7.01, -3.34]5.83 [3.84, 7.60]7% [0%, 22%]11%22%+0.19+0.672026-08-04 → 2026-08-30
tmax00Znearest30d27 1 QC4.82 [3.23, 6.47]2.11-4.80 [-6.46, -3.20]5.54 [3.69, 7.20]7% [0%, 18%]19%30%+0.24+0.672026-08-04 → 2026-08-30
tmax00Znearest90d27 1 QC4.82 [3.09, 6.69]2.11-4.80 [-6.69, -3.06]5.54 [3.60, 7.34]7% [0%, 20%]19%30%+0.24+0.672026-08-04 → 2026-08-30
tmax00Znearest365d27 1 QC4.82 [3.13, 6.75]2.11-4.80 [-6.75, -3.09]5.54 [3.63, 7.41]7% [0%, 21%]19%30%+0.24+0.672026-08-04 → 2026-08-30
tmax00Znearestall27 1 QC4.82 [3.00, 6.72]2.11-4.80 [-6.72, -2.95]5.54 [3.51, 7.35]7% [0%, 22%]19%30%+0.24+0.672026-08-04 → 2026-08-30
tmax12Zbilinear30d27 1 QC5.09 [3.72, 6.50]2.01-5.09 [-6.50, -3.72]5.69 [4.27, 7.01]7% [0%, 18%]11%22%+0.20+0.682026-08-04 → 2026-08-30
tmax12Zbilinear90d27 1 QC5.09 [3.53, 6.67]2.01-5.09 [-6.67, -3.53]5.69 [4.11, 7.12]7% [0%, 20%]11%22%+0.20+0.682026-08-04 → 2026-08-30
tmax12Zbilinear365d27 1 QC5.09 [3.59, 6.64]2.01-5.09 [-6.64, -3.59]5.69 [4.13, 7.17]7% [0%, 21%]11%22%+0.20+0.682026-08-04 → 2026-08-30
tmax12Zbilinearall27 1 QC5.09 [3.49, 6.69]2.01-5.09 [-6.69, -3.49]5.69 [4.04, 7.12]7% [0%, 22%]11%22%+0.20+0.682026-08-04 → 2026-08-30
tmax12Znearest30d27 1 QC4.76 [3.35, 6.22]2.06-4.76 [-6.22, -3.35]5.42 [3.95, 6.76]7% [0%, 18%]22%30%+0.25+0.682026-08-04 → 2026-08-30
tmax12Znearest90d27 1 QC4.76 [3.17, 6.40]2.06-4.76 [-6.40, -3.17]5.42 [3.80, 6.89]7% [0%, 20%]22%30%+0.25+0.682026-08-04 → 2026-08-30
tmax12Znearest365d27 1 QC4.76 [3.22, 6.37]2.06-4.76 [-6.37, -3.22]5.42 [3.81, 6.96]7% [0%, 21%]22%30%+0.25+0.682026-08-04 → 2026-08-30
tmax12Znearestall27 1 QC4.76 [3.11, 6.42]2.06-4.76 [-6.42, -3.11]5.42 [3.73, 6.90]7% [0%, 22%]22%30%+0.25+0.682026-08-04 → 2026-08-30
tmin00Zbilinear30d27 1 QC1.26 [1.04, 1.49]1.22-0.55 [-1.30, 0.17]1.53 [1.30, 1.75]37% [26%, 48%]78%96%+0.45+0.472026-08-04 → 2026-08-30
tmin00Zbilinear90d27 1 QC1.26 [1.02, 1.52]1.22-0.55 [-1.35, 0.17]1.53 [1.29, 1.80]37% [26%, 50%]78%96%+0.45+0.472026-08-04 → 2026-08-30
tmin00Zbilinear365d27 1 QC1.26 [1.03, 1.53]1.22-0.55 [-1.36, 0.23]1.53 [1.27, 1.78]37% [25%, 50%]78%96%+0.45+0.472026-08-04 → 2026-08-30
tmin00Zbilinearall27 1 QC1.26 [1.02, 1.56]1.22-0.55 [-1.48, 0.22]1.53 [1.28, 1.83]37% [25%, 50%]78%96%+0.45+0.472026-08-04 → 2026-08-30
tmin00Znearest30d27 1 QC1.31 [1.07, 1.56]1.29-0.49 [-1.28, 0.26]1.57 [1.33, 1.80]37% [26%, 48%]78%96%+0.43+0.442026-08-04 → 2026-08-30
tmin00Znearest90d27 1 QC1.31 [1.05, 1.60]1.29-0.49 [-1.39, 0.26]1.57 [1.32, 1.85]37% [26%, 50%]78%96%+0.43+0.442026-08-04 → 2026-08-30
tmin00Znearest365d27 1 QC1.31 [1.02, 1.62]1.29-0.49 [-1.36, 0.34]1.57 [1.29, 1.86]37% [25%, 50%]78%96%+0.43+0.442026-08-04 → 2026-08-30
tmin00Znearestall27 1 QC1.31 [1.06, 1.64]1.29-0.49 [-1.50, 0.31]1.57 [1.31, 1.88]37% [25%, 50%]78%96%+0.43+0.442026-08-04 → 2026-08-30
tmin12Zbilinear30d27 1 QC1.25 [1.00, 1.55]1.15-0.58 [-1.32, 0.10]1.56 [1.28, 1.84]41% [28%, 56%]78%93%+0.46+0.502026-08-04 → 2026-08-30
tmin12Zbilinear90d27 1 QC1.25 [0.97, 1.59]1.15-0.58 [-1.44, 0.09]1.56 [1.24, 1.89]41% [27%, 56%]78%93%+0.46+0.502026-08-04 → 2026-08-30
tmin12Zbilinear365d27 1 QC1.25 [0.96, 1.63]1.15-0.58 [-1.42, 0.16]1.56 [1.24, 1.88]41% [25%, 57%]78%93%+0.46+0.502026-08-04 → 2026-08-30
tmin12Zbilinearall27 1 QC1.25 [0.98, 1.66]1.15-0.58 [-1.55, 0.15]1.56 [1.25, 1.93]41% [25%, 57%]78%93%+0.46+0.502026-08-04 → 2026-08-30
tmin12Znearest30d27 1 QC1.32 [1.04, 1.65]1.22-0.54 [-1.35, 0.19]1.59 [1.31, 1.89]44% [30%, 59%]78%93%+0.43+0.472026-08-04 → 2026-08-30
tmin12Znearest90d27 1 QC1.32 [1.01, 1.69]1.22-0.54 [-1.47, 0.18]1.59 [1.24, 1.96]44% [29%, 60%]78%93%+0.43+0.472026-08-04 → 2026-08-30
tmin12Znearest365d27 1 QC1.32 [1.00, 1.69]1.22-0.54 [-1.47, 0.26]1.59 [1.25, 1.96]44% [26%, 60%]78%93%+0.43+0.472026-08-04 → 2026-08-30
tmin12Znearestall27 1 QC1.32 [1.03, 1.73]1.22-0.54 [-1.55, 0.23]1.59 [1.28, 1.99]44% [26%, 59%]78%93%+0.43+0.472026-08-04 → 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 3, 00Z bilinear tmax+20+100-10-202026-08-04: -0.85 °F2026-08-05: -2.88 °F2026-08-06: -3.33 °F2026-08-07: -4.43 °F2026-08-08: -6.71 °F2026-08-09: -4.12 °F2026-08-10: -0.01 °F2026-08-11: -4.75 °F2026-08-12: -5.25 °F2026-08-13: -5.69 °F2026-08-14: -5.66 °F2026-08-15: -1.47 °F2026-08-16: -2.22 °F2026-08-17: -6.42 °F2026-08-18: -9.41 °F2026-08-19: -11.03 °F2026-08-20: -9.47 °F2026-08-21: -10.3 °F2026-08-22: -7.96 °F2026-08-23: -5.37 °F2026-08-24: -5.74 °F2026-08-25: -4.99 °F2026-08-26: -3.3 °F2026-08-27: -4.57 °F2026-08-28: -5.19 °F2026-08-29: -5.7 °F2026-08-30: -2.1 °F2026-08-042026-08-30°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 (27 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-2.10
2026-08-29-5.70
2026-08-28-5.19
2026-08-27-4.57
2026-08-26-3.30
2026-08-25-4.99
2026-08-24-5.74
2026-08-23-5.37
2026-08-22-7.96
2026-08-21-10.30
2026-08-20-9.47
2026-08-19-11.03
2026-08-18-9.41
2026-08-17-6.42
2026-08-16-2.22
2026-08-15-1.47
2026-08-14-5.66
2026-08-13-5.69
2026-08-12-5.25
2026-08-11-4.75
2026-08-10-0.01
2026-08-09-4.12
2026-08-08-6.71
2026-08-07-4.43
2026-08-06-3.33
2026-08-05-2.88
2026-08-04-0.85

Error distribution

Distribution of the signed daily error in °F for ECMWF AIFS Single at KSEA, lead day 3-20 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: 2 days-10 to -8 °F: 2 days-8 to -6 °F: 3 days-6 to -4 °F: 12 days-4 to -2 °F: 5 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| 5.19 · P90 |e| 9.43 °F-200+20 °Fn = 27 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
-12.00-10.002
-10.00-8.002
-8.00-6.003
-6.00-4.0012
-4.00-2.005
-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
2026-08275.15 -5.15

Availability

ModelScored period DaysCoverage
ECMWF AIFS Single2026-08-04 → 2026-08-30 27
ECMWF AIFS Single2026-08-04 → 2026-08-30 27
ECMWF AIFS Single2026-08-04 → 2026-08-30 27
ECMWF AIFS Single2026-08-04 → 2026-08-30 27

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 27 +0.53 [-1.68, 3.10] no
GraphCast (IFS init) 25 +0.70 [-0.00, 1.22] no
ECMWF IFS HRES 22 +2.50 [0.06, 3.96] yes
Persistence (baseline) 27 -1.19 [-5.45, 1.55] no

Cite this page

ShortCastCheck, KSEA aifs_single lead 3, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KSEA/model/aifs_single/lead/3/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KSEA (Seattle-Tacoma), model aifs_single, lead day 3. 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/3/

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