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

Chicago O'Hare · ECMWF IFS HRES · lead day 9

KORD · ifs_hres · lead 9

Target day = initialization date + 9 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, ifs-gpid161, 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
tmax00Zbilinear30d16 1 QC5.73 [4.60, 7.24]4.85-2.56 [-6.78, 0.77]7.03 [5.56, 8.50]6% [0%, 17%]12%38%-0.48-0.252026-08-10 → 2026-08-30
tmax00Zbilinear90d16 1 QC5.73 [4.60, 7.17]4.85-2.56 [-6.71, 0.76]7.03 [5.15, 8.47]6% [0%, 16%]12%38%-0.48-0.252026-08-10 → 2026-08-30
tmax00Zbilinear365d16 1 QC5.73 [4.62, 7.27]4.85-2.56 [-6.99, 1.04]7.03 [5.15, 8.58]6% [0%, 17%]12%38%-0.48-0.252026-08-10 → 2026-08-30
tmax00Zbilinearall16 1 QC5.73 [4.55, 7.40]4.85-2.56 [-7.14, 1.35]7.03 [5.15, 8.74]6% [0%, 17%]12%38%-0.48-0.252026-08-10 → 2026-08-30
tmax00Znearest30d16 1 QC5.51 [4.56, 6.88]4.68-2.31 [-6.42, 0.89]6.65 [5.26, 8.02]6% [0%, 17%]12%31%-0.42-0.212026-08-10 → 2026-08-30
tmax00Znearest90d16 1 QC5.51 [4.48, 6.85]4.68-2.31 [-6.39, 0.91]6.65 [5.19, 8.01]6% [0%, 16%]12%31%-0.42-0.212026-08-10 → 2026-08-30
tmax00Znearest365d16 1 QC5.51 [4.48, 6.95]4.68-2.31 [-6.56, 1.11]6.65 [5.20, 8.12]6% [0%, 17%]12%31%-0.42-0.212026-08-10 → 2026-08-30
tmax00Znearestall16 1 QC5.51 [4.49, 7.01]4.68-2.31 [-6.68, 1.45]6.65 [5.20, 8.16]6% [0%, 17%]12%31%-0.42-0.212026-08-10 → 2026-08-30
tmax12Zbilinear30d15 1 QC4.51 [2.82, 6.45]3.06-4.03 [-6.45, -1.79]5.59 [3.45, 7.46]20% [10%, 36%]27%33%-0.17+0.212026-08-10 → 2026-08-30
tmax12Zbilinear90d15 1 QC4.51 [2.76, 6.85]3.06-4.03 [-6.85, -1.76]5.59 [3.34, 7.76]20% [0%, 33%]27%33%-0.17+0.212026-08-10 → 2026-08-30
tmax12Zbilinear365d15 1 QC4.51 [2.75, 6.85]3.06-4.03 [-6.85, -1.55]5.59 [3.30, 7.72]20% [0%, 40%]27%33%-0.17+0.212026-08-10 → 2026-08-30
tmax12Zbilinearall15 1 QC4.51 [2.65, 6.85]3.06-4.03 [-6.85, -1.59]5.59 [3.16, 7.70]20% [0%, 40%]27%33%-0.17+0.212026-08-10 → 2026-08-30
tmax12Znearest30d15 1 QC4.13 [2.65, 5.85]2.84-3.64 [-5.83, -1.60]5.17 [3.22, 6.91]27% [11%, 44%]27%33%-0.07+0.272026-08-10 → 2026-08-30
tmax12Znearest90d15 1 QC4.13 [2.61, 6.19]2.84-3.64 [-6.19, -1.57]5.17 [3.18, 7.16]27% [0%, 47%]27%33%-0.07+0.272026-08-10 → 2026-08-30
tmax12Znearest365d15 1 QC4.13 [2.61, 6.19]2.84-3.64 [-6.19, -1.40]5.17 [3.14, 7.16]27% [0%, 50%]27%33%-0.07+0.272026-08-10 → 2026-08-30
tmax12Znearestall15 1 QC4.13 [2.52, 6.19]2.84-3.64 [-6.19, -1.45]5.17 [3.02, 7.12]27% [0%, 50%]27%33%-0.07+0.272026-08-10 → 2026-08-30
tmin00Zbilinear30d16 1 QC4.30 [2.21, 5.86]4.37+1.27 [-2.74, 4.26]5.90 [2.72, 7.69]19% [0%, 33%]31%50%+0.21+0.182026-08-10 → 2026-08-30
tmin00Zbilinear90d16 1 QC4.30 [1.47, 5.95]4.37+1.27 [-2.82, 4.20]5.90 [1.72, 7.83]19% [0%, 36%]31%50%+0.21+0.182026-08-10 → 2026-08-30
tmin00Zbilinear365d16 1 QC4.30 [1.66, 5.94]4.37+1.27 [-3.14, 4.40]5.90 [2.07, 7.89]19% [0%, 34%]31%50%+0.21+0.182026-08-10 → 2026-08-30
tmin00Zbilinearall16 1 QC4.30 [1.84, 6.12]4.37+1.27 [-3.26, 4.87]5.90 [2.18, 7.82]19% [0%, 33%]31%50%+0.21+0.182026-08-10 → 2026-08-30
tmin00Znearest30d16 1 QC4.48 [2.47, 6.02]4.62+0.66 [-3.63, 3.85]6.02 [3.12, 7.69]19% [0%, 33%]31%31%+0.18+0.132026-08-10 → 2026-08-30
tmin00Znearest90d16 1 QC4.48 [1.77, 6.08]4.62+0.66 [-3.73, 3.80]6.02 [2.09, 7.83]19% [0%, 36%]31%31%+0.18+0.132026-08-10 → 2026-08-30
tmin00Znearest365d16 1 QC4.48 [1.87, 6.19]4.62+0.66 [-4.17, 3.96]6.02 [2.35, 7.90]19% [0%, 34%]31%31%+0.18+0.132026-08-10 → 2026-08-30
tmin00Znearestall16 1 QC4.48 [1.98, 6.09]4.62+0.66 [-4.15, 4.53]6.02 [2.56, 7.76]19% [0%, 33%]31%31%+0.18+0.132026-08-10 → 2026-08-30
tmin12Zbilinear30d15 1 QC3.13 [1.82, 4.18]2.96-1.13 [-3.63, 0.75]3.88 [2.27, 5.09]13% [0%, 43%]33%47%+0.40+0.432026-08-10 → 2026-08-30
tmin12Zbilinear90d15 1 QC3.13 [0.62, 4.44]2.96-1.13 [-4.04, 0.82]3.88 [0.92, 5.22]13% [0%, 83%]33%47%+0.40+0.432026-08-10 → 2026-08-30
tmin12Zbilinear365d15 1 QC3.13 [0.80, 4.30]2.96-1.13 [-4.01, 0.80]3.88 [1.25, 5.19]13% [0%, 75%]33%47%+0.40+0.432026-08-10 → 2026-08-30
tmin12Zbilinearall15 1 QC3.13 [0.91, 4.32]2.96-1.13 [-3.99, 0.88]3.88 [1.34, 5.12]13% [0%, 75%]33%47%+0.40+0.432026-08-10 → 2026-08-30
tmin12Znearest30d15 1 QC3.41 [1.96, 4.67]3.12-1.84 [-4.36, 0.02]4.28 [2.48, 5.73]27% [6%, 55%]40%47%+0.34+0.402026-08-10 → 2026-08-30
tmin12Znearest90d15 1 QC3.41 [0.84, 5.05]3.12-1.84 [-4.78, 0.16]4.28 [1.19, 5.92]27% [0%, 83%]40%47%+0.34+0.402026-08-10 → 2026-08-30
tmin12Znearest365d15 1 QC3.41 [1.03, 4.92]3.12-1.84 [-4.75, 0.11]4.28 [1.39, 5.83]27% [0%, 82%]40%47%+0.34+0.402026-08-10 → 2026-08-30
tmin12Znearestall15 1 QC3.41 [1.16, 5.00]3.12-1.84 [-4.70, 0.23]4.28 [1.71, 5.78]27% [0%, 75%]40%47%+0.34+0.402026-08-10 → 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 IFS HRES at KORD, lead day 9, 00Z bilinear tmax+20+100-10-202026-08-10: -5.15 °F2026-08-16: -13.27 °F2026-08-17: -2.08 °F2026-08-18: -7.45 °F2026-08-19: +0.37 °F2026-08-20: +8.5 °F2026-08-21: +12.96 °F2026-08-22: -6.27 °F2026-08-23: +1.26 °F2026-08-24: +2.22 °F2026-08-25: -2.41 °F2026-08-26: -3.19 °F2026-08-27: -7.57 °F2026-08-28: -12.05 °F2026-08-29: -4.01 °F2026-08-30: -2.9 °F2026-08-102026-08-30°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 (21 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-2.90
2026-08-29-4.01
2026-08-28-12.05
2026-08-27-7.57
2026-08-26-3.19
2026-08-25-2.41
2026-08-24+2.22
2026-08-23+1.26
2026-08-22-6.27
2026-08-21+12.96
2026-08-20+8.50
2026-08-19+0.37
2026-08-18-7.45
2026-08-17-2.08
2026-08-16-13.27
2026-08-15—
2026-08-14—
2026-08-13—
2026-08-12—
2026-08-11—
2026-08-10-5.15

Error distribution

Distribution of the signed daily error in °F for ECMWF IFS HRES at KORD, lead day 9-20 to -18 °F: 0 days-18 to -16 °F: 0 days-16 to -14 °F: 0 days-14 to -12 °F: 2 days-12 to -10 °F: 0 days-10 to -8 °F: 0 days-8 to -6 °F: 3 days-6 to -4 °F: 2 days-4 to -2 °F: 4 days-2 to 0 °F: 0 days0 to 2 °F: 2 days2 to 4 °F: 1 day4 to 6 °F: 0 days6 to 8 °F: 0 days8 to 10 °F: 1 day10 to 12 °F: 0 days12 to 14 °F: 1 day14 to 16 °F: 0 days16 to 18 °F: 0 days18 to 20 °F: 0 daysdashed: P50 |e| 4.58 · P90 |e| 12.5 °F-200+20 °Fn = 16 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
-14.00-12.002
-12.00-10.000
-10.00-8.000
-8.00-6.003
-6.00-4.002
-4.00-2.004
-2.00+0.000
+0.00+2.002
+2.00+4.001
+4.00+6.000
+6.00+8.000
+8.00+10.001
+10.00+12.000
+12.00+14.001
+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
2026-08165.73 -2.56

Availability

ModelScored period DaysCoverage
ECMWF IFS HRES2026-08-10 → 2026-08-30 16
ECMWF IFS HRES2026-08-10 → 2026-08-30 16
ECMWF IFS HRES2026-08-10 → 2026-08-30 15
ECMWF IFS HRES2026-08-10 → 2026-08-30 15

Compared with other models

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

Other modelCommon days MAE difference °FDistinguishable
ECMWF AIFS Single 16 +0.43 [-2.15, 1.79] no
NCEP GFS 16 -1.22 [-2.95, 1.24] no
GraphCast (IFS init) 16 +0.49 [-4.11, 2.20] no
Persistence (baseline) 16 +1.85 [-6.65, 3.65] no

Cite this page

ShortCastCheck, KORD ifs_hres lead 9, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KORD/model/ifs_hres/lead/9/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KORD (Chicago O'Hare), model ifs_hres, lead day 9. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KORD/model/ifs_hres/lead/9/

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