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

Chicago O'Hare · ECMWF IFS HRES · lead day 4

KORD · ifs_hres · 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, 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
tmax00Zbilinear30d20 1 QC2.51 [1.91, 3.06]1.80-1.98 [-2.82, -0.93]2.91 [2.31, 3.37]25% [7%, 44%]40%60%+0.18+0.422026-08-05 → 2026-08-30
tmax00Zbilinear90d20 1 QC2.51 [1.89, 3.08]1.80-1.98 [-2.81, -0.52]2.91 [2.15, 3.36]25% [0%, 43%]40%60%+0.18+0.422026-08-05 → 2026-08-30
tmax00Zbilinear365d20 1 QC2.51 [1.81, 3.09]1.80-1.98 [-2.90, -0.52]2.91 [2.08, 3.39]25% [0%, 45%]40%60%+0.18+0.422026-08-05 → 2026-08-30
tmax00Zbilinearall20 1 QC2.51 [1.85, 3.08]1.80-1.98 [-2.94, -0.41]2.91 [2.09, 3.37]25% [0%, 43%]40%60%+0.18+0.422026-08-05 → 2026-08-30
tmax00Znearest30d20 1 QC2.41 [1.86, 2.88]1.71-1.83 [-2.66, -0.89]2.77 [2.22, 3.19]15% [0%, 33%]35%80%+0.21+0.452026-08-05 → 2026-08-30
tmax00Znearest90d20 1 QC2.41 [1.87, 2.94]1.71-1.83 [-2.94, -0.51]2.77 [2.21, 3.20]15% [0%, 35%]35%80%+0.21+0.452026-08-05 → 2026-08-30
tmax00Znearest365d20 1 QC2.41 [1.80, 2.94]1.71-1.83 [-2.94, -0.44]2.77 [2.14, 3.24]15% [0%, 38%]35%80%+0.21+0.452026-08-05 → 2026-08-30
tmax00Znearestall20 1 QC2.41 [1.87, 2.94]1.71-1.83 [-2.94, -0.40]2.77 [2.24, 3.24]15% [0%, 33%]35%80%+0.21+0.452026-08-05 → 2026-08-30
tmax12Zbilinear30d21 1 QC2.50 [1.94, 3.06]1.70-1.95 [-2.91, -0.97]2.94 [2.21, 3.51]24% [9%, 36%]33%62%+0.17+0.452026-08-05 → 2026-08-30
tmax12Zbilinear90d21 1 QC2.50 [1.87, 3.10]1.70-1.95 [-2.99, -0.84]2.94 [2.12, 3.55]24% [0%, 38%]33%62%+0.17+0.452026-08-05 → 2026-08-30
tmax12Zbilinear365d21 1 QC2.50 [1.82, 3.14]1.70-1.95 [-3.03, -0.63]2.94 [2.06, 3.57]24% [0%, 38%]33%62%+0.17+0.452026-08-05 → 2026-08-30
tmax12Zbilinearall21 1 QC2.50 [1.85, 3.16]1.70-1.95 [-3.15, -0.73]2.94 [2.04, 3.61]24% [0%, 37%]33%62%+0.17+0.452026-08-05 → 2026-08-30
tmax12Znearest30d21 1 QC2.25 [1.71, 2.84]1.62-1.72 [-2.66, -0.74]2.73 [2.03, 3.31]33% [21%, 44%]52%67%+0.25+0.472026-08-05 → 2026-08-30
tmax12Znearest90d21 1 QC2.25 [1.63, 3.08]1.62-1.72 [-3.06, -0.66]2.73 [1.95, 3.33]33% [20%, 45%]52%67%+0.25+0.472026-08-05 → 2026-08-30
tmax12Znearest365d21 1 QC2.25 [1.57, 3.09]1.62-1.72 [-3.09, -0.50]2.73 [1.82, 3.45]33% [20%, 45%]52%67%+0.25+0.472026-08-05 → 2026-08-30
tmax12Znearestall21 1 QC2.25 [1.63, 3.09]1.62-1.72 [-3.09, -0.58]2.73 [1.87, 3.47]33% [17%, 45%]52%67%+0.25+0.472026-08-05 → 2026-08-30
tmin00Zbilinear30d20 1 QC2.29 [1.33, 3.01]2.16+0.82 [-0.93, 2.52]3.27 [1.84, 4.02]35% [18%, 55%]75%75%+0.36+0.392026-08-05 → 2026-08-30
tmin00Zbilinear90d20 1 QC2.29 [1.13, 3.04]2.16+0.82 [-1.16, 2.49]3.27 [1.25, 3.98]35% [13%, 56%]75%75%+0.36+0.392026-08-05 → 2026-08-30
tmin00Zbilinear365d20 1 QC2.29 [1.10, 3.05]2.16+0.82 [-1.18, 2.67]3.27 [1.21, 4.00]35% [14%, 59%]75%75%+0.36+0.392026-08-05 → 2026-08-30
tmin00Zbilinearall20 1 QC2.29 [1.20, 2.97]2.16+0.82 [-1.17, 2.43]3.27 [1.29, 3.97]35% [12%, 58%]75%75%+0.36+0.392026-08-05 → 2026-08-30
tmin00Znearest30d20 1 QC2.08 [1.24, 2.75]2.03+0.42 [-1.29, 2.11]3.09 [1.54, 3.83]45% [24%, 71%]75%75%+0.42+0.432026-08-05 → 2026-08-30
tmin00Znearest90d20 1 QC2.08 [1.06, 2.75]2.03+0.42 [-1.53, 2.10]3.09 [1.28, 3.74]45% [20%, 71%]75%75%+0.42+0.432026-08-05 → 2026-08-30
tmin00Znearest365d20 1 QC2.08 [1.06, 2.79]2.03+0.42 [-1.56, 2.30]3.09 [1.24, 3.76]45% [19%, 75%]75%75%+0.42+0.432026-08-05 → 2026-08-30
tmin00Znearestall20 1 QC2.08 [1.11, 2.72]2.03+0.42 [-1.56, 2.06]3.09 [1.34, 3.78]45% [17%, 75%]75%75%+0.42+0.432026-08-05 → 2026-08-30
tmin12Zbilinear30d21 1 QC2.07 [1.20, 2.70]1.98+0.56 [-1.04, 1.77]2.85 [1.73, 3.44]38% [13%, 67%]57%76%+0.43+0.452026-08-05 → 2026-08-30
tmin12Zbilinear90d21 1 QC2.07 [0.85, 2.66]1.98+0.56 [-1.15, 1.88]2.85 [1.05, 3.39]38% [13%, 73%]57%76%+0.43+0.452026-08-05 → 2026-08-30
tmin12Zbilinear365d21 1 QC2.07 [0.76, 2.70]1.98+0.56 [-1.18, 1.88]2.85 [0.89, 3.40]38% [10%, 75%]57%76%+0.43+0.452026-08-05 → 2026-08-30
tmin12Zbilinearall21 1 QC2.07 [0.36, 2.74]1.98+0.56 [-1.12, 1.79]2.85 [0.38, 3.41]38% [10%, 100%]57%76%+0.43+0.452026-08-05 → 2026-08-30
tmin12Znearest30d21 1 QC1.84 [0.94, 2.48]1.84+0.02 [-1.38, 1.12]2.73 [1.39, 3.33]52% [27%, 79%]67%76%+0.49+0.492026-08-05 → 2026-08-30
tmin12Znearest90d21 1 QC1.84 [0.68, 2.41]1.84+0.02 [-1.48, 1.21]2.73 [0.92, 3.28]52% [28%, 86%]67%76%+0.49+0.492026-08-05 → 2026-08-30
tmin12Znearest365d21 1 QC1.84 [0.65, 2.46]1.84+0.02 [-1.53, 1.20]2.73 [0.91, 3.27]52% [25%, 100%]67%76%+0.49+0.492026-08-05 → 2026-08-30
tmin12Znearestall21 1 QC1.84 [0.36, 2.48]1.84+0.02 [-1.46, 1.16]2.73 [0.36, 3.29]52% [25%, 100%]67%76%+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 IFS HRES at KORD, lead day 4, 00Z bilinear tmax+5+2.50-2.5-52026-08-05: -1.89 °F2026-08-11: -2.69 °F2026-08-12: -1.09 °F2026-08-13: -4.62 °F2026-08-14: +0.24 °F2026-08-16: +0.73 °F2026-08-17: -3.46 °F2026-08-18: -0.6 °F2026-08-19: -3.45 °F2026-08-20: -0.58 °F2026-08-21: -2.01 °F2026-08-22: -4.72 °F2026-08-23: -2.4 °F2026-08-24: -3.13 °F2026-08-25: -4.98 °F2026-08-26: -4.17 °F2026-08-27: -0.98 °F2026-08-28: -4.08 °F2026-08-29: +1.82 °F2026-08-30: +2.5 °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+2.50
2026-08-29+1.82
2026-08-28-4.08
2026-08-27-0.98
2026-08-26-4.17
2026-08-25-4.98
2026-08-24-3.13
2026-08-23-2.40
2026-08-22-4.72
2026-08-21-2.01
2026-08-20-0.58
2026-08-19-3.45
2026-08-18-0.60
2026-08-17-3.46
2026-08-16+0.73
2026-08-15—
2026-08-14+0.24
2026-08-13-4.62
2026-08-12-1.09
2026-08-11-2.69
2026-08-10—
2026-08-09—
2026-08-08—
2026-08-07—
2026-08-06—
2026-08-05-1.89

Error distribution

Distribution of the signed daily error in °F for ECMWF IFS HRES at KORD, lead day 4-5 to -4.5 °F: 3 days-4.5 to -4 °F: 2 days-4 to -3.5 °F: 0 days-3.5 to -3 °F: 3 days-3 to -2.5 °F: 1 day-2.5 to -2 °F: 2 days-2 to -1.5 °F: 1 day-1.5 to -1 °F: 1 day-1 to -0.5 °F: 3 days-0.5 to 0 °F: 0 days0 to 0.5 °F: 1 day0.5 to 1 °F: 1 day1 to 1.5 °F: 0 days1.5 to 2 °F: 1 day2 to 2.5 °F: 0 days2.5 to 3 °F: 1 day3 to 3.5 °F: 0 days3.5 to 4 °F: 0 days4 to 4.5 °F: 0 days4.5 to 5 °F: 0 daysdashed: P50 |e| 2.45 · P90 |e| 4.63 °F-50+5 °Fn = 20 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
-5.00-4.503
-4.50-4.002
-4.00-3.500
-3.50-3.003
-3.00-2.501
-2.50-2.002
-2.00-1.501
-1.50-1.001
-1.00-0.503
-0.50+0.000
+0.00+0.501
+0.50+1.001
+1.00+1.500
+1.50+2.001
+2.00+2.500
+2.50+3.001
+3.00+3.500
+3.50+4.000
+4.00+4.500
+4.50+5.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08202.51 -1.98

Availability

ModelScored period DaysCoverage
ECMWF IFS HRES2026-08-05 → 2026-08-30 20
ECMWF IFS HRES2026-08-05 → 2026-08-30 20
ECMWF IFS HRES2026-08-05 → 2026-08-30 21
ECMWF IFS HRES2026-08-05 → 2026-08-30 21

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 20 -0.68 [-1.61, -0.08] yes
NCEP GFS 20 -0.12 [-2.19, 1.64] no
GraphCast (IFS init) 19 -1.24 [-2.17, -0.29] yes
Persistence (baseline) 20 -0.54 [-3.57, 0.70] no

Cite this page

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

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KORD (Chicago O'Hare), model ifs_hres, 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/KORD/model/ifs_hres/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