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

Chicago O'Hare · ECMWF AIFS Single · lead day 1

KORD · aifs_single · lead 1

Target day = initialization date + 1 day. 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
tmax00Zbilinear30d29 1 QC3.29 [2.72, 3.85]1.01-3.29 [-3.85, -2.72]3.56 [2.89, 4.12]3% [0%, 10%]17%52%-0.12+0.652026-08-02 → 2026-08-30
tmax00Zbilinear90d29 1 QC3.29 [2.71, 3.95]1.01-3.29 [-3.95, -2.71]3.56 [2.84, 4.22]3% [0%, 10%]17%52%-0.12+0.652026-08-02 → 2026-08-30
tmax00Zbilinear365d29 1 QC3.29 [2.69, 3.91]1.01-3.29 [-3.91, -2.69]3.56 [2.82, 4.21]3% [0%, 11%]17%52%-0.12+0.652026-08-02 → 2026-08-30
tmax00Zbilinearall29 1 QC3.29 [2.68, 3.92]1.01-3.29 [-3.92, -2.68]3.56 [2.77, 4.25]3% [0%, 10%]17%52%-0.12+0.652026-08-02 → 2026-08-30
tmax00Znearest30d29 1 QC2.83 [2.23, 3.43]1.05-2.83 [-3.43, -2.23]3.18 [2.40, 3.81]3% [0%, 10%]24%72%+0.03+0.642026-08-02 → 2026-08-30
tmax00Znearest90d29 1 QC2.83 [2.21, 3.49]1.05-2.83 [-3.49, -2.21]3.18 [2.36, 3.88]3% [0%, 10%]24%72%+0.03+0.642026-08-02 → 2026-08-30
tmax00Znearest365d29 1 QC2.83 [2.22, 3.48]1.05-2.83 [-3.48, -2.22]3.18 [2.37, 3.93]3% [0%, 11%]24%72%+0.03+0.642026-08-02 → 2026-08-30
tmax00Znearestall29 1 QC2.83 [2.20, 3.50]1.05-2.83 [-3.50, -2.20]3.18 [2.33, 3.93]3% [0%, 10%]24%72%+0.03+0.642026-08-02 → 2026-08-30
tmax12Zbilinear30d29 1 QC3.30 [2.66, 3.94]1.15-3.30 [-3.94, -2.66]3.58 [2.85, 4.21]3% [0%, 10%]10%52%-0.12+0.602026-08-02 → 2026-08-30
tmax12Zbilinear90d29 1 QC3.30 [2.59, 4.09]1.15-3.30 [-4.09, -2.59]3.58 [2.76, 4.35]3% [0%, 10%]10%52%-0.12+0.602026-08-02 → 2026-08-30
tmax12Zbilinear365d29 1 QC3.30 [2.59, 4.08]1.15-3.30 [-4.08, -2.59]3.58 [2.76, 4.31]3% [0%, 11%]10%52%-0.12+0.602026-08-02 → 2026-08-30
tmax12Zbilinearall29 1 QC3.30 [2.57, 4.08]1.15-3.30 [-4.08, -2.57]3.58 [2.71, 4.35]3% [0%, 10%]10%52%-0.12+0.602026-08-02 → 2026-08-30
tmax12Znearest30d29 1 QC2.80 [2.12, 3.48]1.22-2.80 [-3.48, -2.12]3.16 [2.34, 3.83]3% [0%, 10%]34%59%+0.04+0.582026-08-02 → 2026-08-30
tmax12Znearest90d29 1 QC2.80 [2.05, 3.59]1.22-2.80 [-3.59, -2.05]3.16 [2.24, 3.95]3% [0%, 10%]34%59%+0.04+0.582026-08-02 → 2026-08-30
tmax12Znearest365d29 1 QC2.80 [2.06, 3.56]1.22-2.80 [-3.56, -2.06]3.16 [2.22, 3.92]3% [0%, 11%]34%59%+0.04+0.582026-08-02 → 2026-08-30
tmax12Znearestall29 1 QC2.80 [2.06, 3.59]1.22-2.80 [-3.58, -2.06]3.16 [2.22, 3.94]3% [0%, 10%]34%59%+0.04+0.582026-08-02 → 2026-08-30
tmin00Zbilinear30d29 1 QC1.71 [1.44, 2.03]1.69+0.51 [-0.59, 1.28]2.04 [1.73, 2.34]34% [28%, 41%]55%83%+0.39+0.412026-08-02 → 2026-08-30
tmin00Zbilinear90d29 1 QC1.71 [1.36, 2.11]1.69+0.51 [-0.69, 1.47]2.04 [1.65, 2.40]34% [25%, 43%]55%83%+0.39+0.412026-08-02 → 2026-08-30
tmin00Zbilinear365d29 1 QC1.71 [1.36, 2.12]1.69+0.51 [-0.79, 1.45]2.04 [1.65, 2.41]34% [25%, 43%]55%83%+0.39+0.412026-08-02 → 2026-08-30
tmin00Zbilinearall29 1 QC1.71 [1.38, 2.15]1.69+0.51 [-0.73, 1.46]2.04 [1.67, 2.44]34% [25%, 43%]55%83%+0.39+0.412026-08-02 → 2026-08-30
tmin00Znearest30d29 1 QC1.86 [1.47, 2.24]1.86-0.11 [-1.39, 0.82]2.18 [1.78, 2.54]31% [17%, 46%]55%79%+0.34+0.352026-08-02 → 2026-08-30
tmin00Znearest90d29 1 QC1.86 [1.42, 2.28]1.86-0.11 [-1.52, 1.04]2.18 [1.71, 2.57]31% [15%, 48%]55%79%+0.34+0.352026-08-02 → 2026-08-30
tmin00Znearest365d29 1 QC1.86 [1.42, 2.29]1.86-0.11 [-1.62, 1.00]2.18 [1.72, 2.60]31% [14%, 49%]55%79%+0.34+0.352026-08-02 → 2026-08-30
tmin00Znearestall29 1 QC1.86 [1.43, 2.31]1.86-0.11 [-1.60, 1.03]2.18 [1.71, 2.58]31% [14%, 48%]55%79%+0.34+0.352026-08-02 → 2026-08-30
tmin12Zbilinear30d29 1 QC1.71 [1.41, 2.03]1.67+0.66 [-0.42, 1.45]2.03 [1.70, 2.35]31% [14%, 50%]69%83%+0.39+0.412026-08-02 → 2026-08-30
tmin12Zbilinear90d29 1 QC1.71 [1.36, 2.07]1.67+0.66 [-0.49, 1.58]2.03 [1.67, 2.38]31% [12%, 52%]69%83%+0.39+0.412026-08-02 → 2026-08-30
tmin12Zbilinear365d29 1 QC1.71 [1.32, 2.09]1.67+0.66 [-0.63, 1.59]2.03 [1.62, 2.39]31% [12%, 55%]69%83%+0.39+0.412026-08-02 → 2026-08-30
tmin12Zbilinearall29 1 QC1.71 [1.36, 2.12]1.67+0.66 [-0.57, 1.59]2.03 [1.67, 2.41]31% [12%, 56%]69%83%+0.39+0.412026-08-02 → 2026-08-30
tmin12Znearest30d29 1 QC1.83 [1.53, 2.14]1.83+0.07 [-1.20, 1.01]2.10 [1.75, 2.42]28% [17%, 38%]69%86%+0.35+0.362026-08-02 → 2026-08-30
tmin12Znearest90d29 1 QC1.83 [1.49, 2.15]1.83+0.07 [-1.29, 1.16]2.10 [1.70, 2.42]28% [14%, 38%]69%86%+0.35+0.362026-08-02 → 2026-08-30
tmin12Znearest365d29 1 QC1.83 [1.47, 2.17]1.83+0.07 [-1.46, 1.15]2.10 [1.67, 2.45]28% [14%, 38%]69%86%+0.35+0.362026-08-02 → 2026-08-30
tmin12Znearestall29 1 QC1.83 [1.50, 2.18]1.83+0.07 [-1.43, 1.19]2.10 [1.71, 2.43]28% [16%, 38%]69%86%+0.35+0.362026-08-02 → 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 KORD, lead day 1, 00Z bilinear tmax+10+50-5-102026-08-02: -1.96 °F2026-08-03: -4.85 °F2026-08-04: -3.36 °F2026-08-05: -6.41 °F2026-08-06: -3.43 °F2026-08-07: -3.14 °F2026-08-08: -2.27 °F2026-08-09: -5.06 °F2026-08-10: -5.95 °F2026-08-11: -3.11 °F2026-08-12: -6.36 °F2026-08-13: -2 °F2026-08-14: -3.71 °F2026-08-15: -0.6 °F2026-08-16: -2.78 °F2026-08-17: -2.95 °F2026-08-18: -2.63 °F2026-08-19: -1.78 °F2026-08-20: -2.4 °F2026-08-21: -2.77 °F2026-08-22: -3.52 °F2026-08-23: -2.72 °F2026-08-24: -3.16 °F2026-08-25: -4.9 °F2026-08-26: -1.89 °F2026-08-27: -2.8 °F2026-08-28: -3.27 °F2026-08-29: -2.87 °F2026-08-30: -2.67 °F2026-08-022026-08-30°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 (29 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-2.67
2026-08-29-2.87
2026-08-28-3.27
2026-08-27-2.80
2026-08-26-1.89
2026-08-25-4.90
2026-08-24-3.16
2026-08-23-2.72
2026-08-22-3.52
2026-08-21-2.77
2026-08-20-2.40
2026-08-19-1.78
2026-08-18-2.63
2026-08-17-2.95
2026-08-16-2.78
2026-08-15-0.60
2026-08-14-3.71
2026-08-13-2.00
2026-08-12-6.36
2026-08-11-3.11
2026-08-10-5.95
2026-08-09-5.06
2026-08-08-2.27
2026-08-07-3.14
2026-08-06-3.43
2026-08-05-6.41
2026-08-04-3.36
2026-08-03-4.85
2026-08-02-1.96

Error distribution

Distribution of the signed daily error in °F for ECMWF AIFS Single at KORD, lead day 1-10 to -9 °F: 0 days-9 to -8 °F: 0 days-8 to -7 °F: 0 days-7 to -6 °F: 2 days-6 to -5 °F: 2 days-5 to -4 °F: 2 days-4 to -3 °F: 8 days-3 to -2 °F: 10 days-2 to -1 °F: 4 days-1 to 0 °F: 1 day0 to 1 °F: 0 days1 to 2 °F: 0 days2 to 3 °F: 0 days3 to 4 °F: 0 days4 to 5 °F: 0 days5 to 6 °F: 0 days6 to 7 °F: 0 days7 to 8 °F: 0 days8 to 9 °F: 0 days9 to 10 °F: 0 daysdashed: P50 |e| 2.95 · P90 |e| 5.24 °F-100+10 °Fn = 29 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
-10.00-9.000
-9.00-8.000
-8.00-7.000
-7.00-6.002
-6.00-5.002
-5.00-4.002
-4.00-3.008
-3.00-2.0010
-2.00-1.004
-1.00+0.001
+0.00+1.000
+1.00+2.000
+2.00+3.000
+3.00+4.000
+4.00+5.000
+5.00+6.000
+6.00+7.000
+7.00+8.000
+8.00+9.000
+9.00+10.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08293.29 -3.29

Availability

ModelScored period DaysCoverage
ECMWF AIFS Single2026-08-02 → 2026-08-30 29
ECMWF AIFS Single2026-08-02 → 2026-08-30 29
ECMWF AIFS Single2026-08-02 → 2026-08-30 29
ECMWF AIFS Single2026-08-02 → 2026-08-30 29

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
Aurora (GFS init) 1 -4.02 [-4.02, -4.02] yes
Aurora (IFS init) 2 +0.07 [-0.03, 0.18] no
FourCastNet v2 (GFS init) 1 +0.04 [0.04, 0.04] yes
FourCastNet v2 (IFS init) 2 +0.32 [0.16, 0.47] yes
NCEP GFS 29 +0.72 [0.35, 1.14] yes
GraphCast (GFS init) 1 -4.27 [-4.27, -4.27] yes
GraphCast (IFS init) 27 -0.21 [-0.92, 0.31] no
ECMWF IFS HRES 23 +0.15 [-0.67, 1.07] no
Pangu-Weather (GFS init) 1 -1.56 [-1.56, -1.56] yes
Pangu-Weather (IFS init) 2 -1.25 [-1.33, -1.16] yes
Persistence (baseline) 29 +0.36 [-0.46, 1.17] no

Cite this page

ShortCastCheck, KORD aifs_single lead 1, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KORD/model/aifs_single/lead/1/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KORD (Chicago O'Hare), model aifs_single, lead day 1. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KORD/model/aifs_single/lead/1/

Accessed2026-08-31 (data through 2026-08-30; page built 2026-08-31T03:52:06+00:00)

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