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

Chicago O'Hare · ECMWF IFS HRES · lead day 8

KORD · ifs_hres · 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, 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
tmax00Zbilinear30d17 1 QC5.13 [3.35, 6.10]4.13-2.53 [-4.72, 0.05]6.25 [4.24, 7.40]6% [0%, 33%]18%29%-0.36-0.082026-08-09 → 2026-08-30
tmax00Zbilinear90d17 1 QC5.13 [1.53, 6.16]4.13-2.53 [-4.74, 0.21]6.25 [2.15, 7.44]6% [0%, 53%]18%29%-0.36-0.082026-08-09 → 2026-08-30
tmax00Zbilinear365d17 1 QC5.13 [1.47, 6.24]4.13-2.53 [-4.76, 0.21]6.25 [1.98, 7.47]6% [0%, 50%]18%29%-0.36-0.082026-08-09 → 2026-08-30
tmax00Zbilinearall17 1 QC5.13 [1.66, 6.20]4.13-2.53 [-4.80, 0.21]6.25 [2.40, 7.45]6% [0%, 50%]18%29%-0.36-0.082026-08-09 → 2026-08-30
tmax00Znearest30d17 1 QC4.85 [3.00, 5.77]3.96-2.16 [-4.24, 0.25]5.94 [3.90, 7.11]6% [0%, 33%]12%35%-0.29-0.032026-08-09 → 2026-08-30
tmax00Znearest90d17 1 QC4.85 [1.24, 5.80]3.96-2.16 [-4.28, 0.26]5.94 [1.98, 7.13]6% [0%, 53%]12%35%-0.29-0.032026-08-09 → 2026-08-30
tmax00Znearest365d17 1 QC4.85 [1.23, 5.91]3.96-2.16 [-4.23, 0.29]5.94 [1.70, 7.18]6% [0%, 50%]12%35%-0.29-0.032026-08-09 → 2026-08-30
tmax00Znearestall17 1 QC4.85 [1.52, 5.90]3.96-2.16 [-4.32, 0.23]5.94 [2.28, 7.16]6% [0%, 50%]12%35%-0.29-0.032026-08-09 → 2026-08-30
tmax12Zbilinear30d17 1 QC4.82 [3.29, 6.64]3.77-3.95 [-6.27, -0.97]5.84 [4.28, 7.26]12% [0%, 26%]24%41%-0.28+0.022026-08-09 → 2026-08-30
tmax12Zbilinear90d17 1 QC4.82 [3.22, 6.82]3.77-3.95 [-6.61, 2.38]5.84 [3.86, 7.39]12% [0%, 28%]24%41%-0.28+0.022026-08-09 → 2026-08-30
tmax12Zbilinear365d17 1 QC4.82 [3.21, 6.77]3.77-3.95 [-6.60, 2.38]5.84 [3.86, 7.37]12% [0%, 27%]24%41%-0.28+0.022026-08-09 → 2026-08-30
tmax12Zbilinearall17 1 QC4.82 [3.33, 6.77]3.77-3.95 [-6.74, 1.52]5.84 [3.86, 7.38]12% [0%, 29%]24%41%-0.28+0.022026-08-09 → 2026-08-30
tmax12Znearest30d17 1 QC4.69 [3.21, 6.47]3.69-3.78 [-6.08, -0.76]5.65 [4.01, 7.16]6% [0%, 13%]24%47%-0.25+0.042026-08-09 → 2026-08-30
tmax12Znearest90d17 1 QC4.69 [3.16, 6.59]3.69-3.78 [-6.41, 2.58]5.65 [3.75, 7.21]6% [0%, 14%]24%47%-0.25+0.042026-08-09 → 2026-08-30
tmax12Znearest365d17 1 QC4.69 [3.12, 6.61]3.69-3.78 [-6.41, 2.58]5.65 [3.75, 7.21]6% [0%, 14%]24%47%-0.25+0.042026-08-09 → 2026-08-30
tmax12Znearestall17 1 QC4.69 [3.23, 6.60]3.69-3.78 [-6.49, 1.66]5.65 [3.75, 7.21]6% [0%, 14%]24%47%-0.25+0.042026-08-09 → 2026-08-30
tmin00Zbilinear30d17 1 QC3.66 [2.30, 5.34]3.72+0.98 [-0.97, 3.09]4.91 [2.87, 6.50]18% [0%, 44%]41%53%+0.24+0.252026-08-09 → 2026-08-30
tmin00Zbilinear90d17 1 QC3.66 [2.21, 5.70]3.72+0.98 [-1.42, 4.12]4.91 [2.70, 6.72]18% [0%, 45%]41%53%+0.24+0.252026-08-09 → 2026-08-30
tmin00Zbilinear365d17 1 QC3.66 [2.29, 5.93]3.72+0.98 [-1.35, 3.97]4.91 [2.74, 6.69]18% [0%, 46%]41%53%+0.24+0.252026-08-09 → 2026-08-30
tmin00Zbilinearall17 1 QC3.66 [2.09, 5.68]3.72+0.98 [-1.69, 3.94]4.91 [2.68, 6.69]18% [0%, 50%]41%53%+0.24+0.252026-08-09 → 2026-08-30
tmin00Znearest30d17 1 QC3.55 [2.40, 4.92]3.60+0.32 [-1.60, 2.42]4.75 [2.89, 6.21]18% [8%, 29%]35%59%+0.26+0.272026-08-09 → 2026-08-30
tmin00Znearest90d17 1 QC3.55 [2.32, 5.16]3.60+0.32 [-2.08, 3.30]4.75 [2.79, 6.26]18% [0%, 30%]35%59%+0.26+0.272026-08-09 → 2026-08-30
tmin00Znearest365d17 1 QC3.55 [2.36, 5.32]3.60+0.32 [-1.99, 3.23]4.75 [2.80, 6.28]18% [0%, 30%]35%59%+0.26+0.272026-08-09 → 2026-08-30
tmin00Znearestall17 1 QC3.55 [2.22, 5.12]3.60+0.32 [-2.30, 3.17]4.75 [2.62, 6.28]18% [0%, 31%]35%59%+0.26+0.272026-08-09 → 2026-08-30
tmin12Zbilinear30d17 1 QC3.50 [2.62, 5.20]3.54+0.42 [-1.53, 3.20]4.25 [3.13, 6.11]18% [0%, 35%]24%53%+0.27+0.292026-08-09 → 2026-08-30
tmin12Zbilinear90d17 1 QC3.50 [2.57, 6.44]3.54+0.42 [-1.81, 4.67]4.25 [3.01, 7.22]18% [0%, 33%]24%53%+0.27+0.292026-08-09 → 2026-08-30
tmin12Zbilinear365d17 1 QC3.50 [2.49, 6.34]3.54+0.42 [-1.74, 4.47]4.25 [3.00, 7.09]18% [0%, 38%]24%53%+0.27+0.292026-08-09 → 2026-08-30
tmin12Zbilinearall17 1 QC3.50 [2.31, 6.34]3.54+0.42 [-2.03, 4.46]4.25 [2.59, 7.09]18% [0%, 36%]24%53%+0.27+0.292026-08-09 → 2026-08-30
tmin12Znearest30d17 1 QC3.76 [3.03, 5.34]3.72-0.21 [-2.26, 2.69]4.47 [3.56, 6.21]12% [0%, 22%]24%41%+0.22+0.252026-08-09 → 2026-08-30
tmin12Znearest90d17 1 QC3.76 [3.02, 6.68]3.72-0.21 [-2.58, 4.17]4.47 [3.45, 7.25]12% [0%, 22%]24%41%+0.22+0.252026-08-09 → 2026-08-30
tmin12Znearest365d17 1 QC3.76 [2.94, 6.60]3.72-0.21 [-2.56, 4.03]4.47 [3.34, 7.14]12% [0%, 25%]24%41%+0.22+0.252026-08-09 → 2026-08-30
tmin12Znearestall17 1 QC3.76 [2.81, 6.60]3.72-0.21 [-2.84, 4.05]4.47 [3.25, 7.14]12% [0%, 22%]24%41%+0.22+0.252026-08-09 → 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 IFS HRES at KORD, lead day 8, 00Z bilinear tmax+20+100-10-202026-08-09: +0.21 °F2026-08-15: +4.26 °F2026-08-16: -11.08 °F2026-08-17: -5.05 °F2026-08-18: -3.44 °F2026-08-19: +1.53 °F2026-08-20: +14.36 °F2026-08-21: -3.44 °F2026-08-22: -8.09 °F2026-08-23: +1.73 °F2026-08-24: -2.89 °F2026-08-25: -3.93 °F2026-08-26: -7.19 °F2026-08-27: -8.47 °F2026-08-28: -5.6 °F2026-08-29: -3.78 °F2026-08-30: -2.12 °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
2026-08-30-2.12
2026-08-29-3.78
2026-08-28-5.60
2026-08-27-8.47
2026-08-26-7.19
2026-08-25-3.93
2026-08-24-2.89
2026-08-23+1.73
2026-08-22-8.09
2026-08-21-3.44
2026-08-20+14.36
2026-08-19+1.53
2026-08-18-3.44
2026-08-17-5.05
2026-08-16-11.08
2026-08-15+4.26
2026-08-14—
2026-08-13—
2026-08-12—
2026-08-11—
2026-08-10—
2026-08-09+0.21

Error distribution

Distribution of the signed daily error in °F for ECMWF IFS HRES at KORD, lead day 8-20 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: 1 day-10 to -8 °F: 2 days-8 to -6 °F: 1 day-6 to -4 °F: 2 days-4 to -2 °F: 6 days-2 to 0 °F: 0 days0 to 2 °F: 3 days2 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: 1 day16 to 18 °F: 0 days18 to 20 °F: 0 daysdashed: P50 |e| 3.93 · P90 |e| 9.52 °F-200+20 °Fn = 17 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
-12.00-10.001
-10.00-8.002
-8.00-6.001
-6.00-4.002
-4.00-2.006
-2.00+0.000
+0.00+2.003
+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+16.001
+16.00+18.000
+18.00+20.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08175.13 -2.53

Availability

ModelScored period DaysCoverage
ECMWF IFS HRES2026-08-09 → 2026-08-30 17
ECMWF IFS HRES2026-08-09 → 2026-08-30 17
ECMWF IFS HRES2026-08-09 → 2026-08-30 17
ECMWF IFS HRES2026-08-09 → 2026-08-30 17

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 17 -0.52 [-2.58, 1.52] no
NCEP GFS 17 +0.96 [-1.50, 2.95] no
GraphCast (IFS init) 17 +0.74 [-3.17, 2.63] no
Persistence (baseline) 17 +1.36 [-7.26, 2.90] no

Cite this page

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

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