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

Denver Intl · GraphCast (IFS init) · lead day 1

KDEN · graphcast_ifs · 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, GRAP_v100, starting 2026-01-01 — 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 QC5.92 [5.19, 6.62]1.42-5.92 [-6.62, -5.19]6.21 [5.43, 6.89]0% [0%, 0%]4%7%-0.02+0.762026-08-02 → 2026-08-30
tmax00Zbilinear90d27 1 QC5.92 [5.07, 6.57]1.42-5.92 [-6.57, -5.07]6.21 [5.32, 6.84]0% [0%, 0%]4%7%-0.02+0.762026-08-02 → 2026-08-30
tmax00Zbilinear365d33 1 QC6.26 [5.46, 7.19]1.57-6.26 [-7.19, -5.46]6.58 [5.69, 7.49]0% [0%, 0%]3%6%-0.15+0.712026-01-02 → 2026-08-30
tmax00Zbilinearall33 1 QC6.26 [5.33, 7.06]1.57-6.26 [-7.06, -5.33]6.58 [5.53, 7.36]0% [0%, 0%]3%6%-0.15+0.712026-01-02 → 2026-08-30
tmax00Znearest30d27 1 QC6.07 [5.25, 6.81]1.47-6.07 [-6.81, -5.25]6.38 [5.56, 7.09]0% [0%, 0%]4%7%-0.04+0.752026-08-02 → 2026-08-30
tmax00Znearest90d27 1 QC6.07 [5.15, 6.76]1.47-6.07 [-6.76, -5.15]6.38 [5.43, 7.04]0% [0%, 0%]4%7%-0.04+0.752026-08-02 → 2026-08-30
tmax00Znearest365d33 1 QC6.39 [5.57, 7.27]1.57-6.39 [-7.27, -5.57]6.71 [5.85, 7.57]0% [0%, 0%]3%6%-0.18+0.712026-01-02 → 2026-08-30
tmax00Znearestall33 1 QC6.39 [5.39, 7.20]1.57-6.39 [-7.20, -5.39]6.71 [5.70, 7.48]0% [0%, 0%]3%6%-0.18+0.712026-01-02 → 2026-08-30
tmax12Zbilinear30d27 1 QC6.82 [5.95, 7.49]1.56-6.82 [-7.49, -5.95]7.11 [6.35, 7.67]0% [0%, 0%]4%4%-0.17+0.732026-08-02 → 2026-08-30
tmax12Zbilinear90d27 1 QC6.82 [5.85, 7.48]1.56-6.82 [-7.48, -5.85]7.11 [6.23, 7.67]0% [0%, 0%]4%4%-0.17+0.732026-08-02 → 2026-08-30
tmax12Zbilinear365d32 1 QC7.02 [6.23, 7.75]1.56-7.02 [-7.75, -6.23]7.30 [6.58, 7.95]0% [0%, 0%]3%3%-0.26+0.722026-01-02 → 2026-08-30
tmax12Zbilinearall32 1 QC7.02 [6.02, 7.72]1.56-7.02 [-7.72, -6.02]7.30 [6.42, 7.91]0% [0%, 0%]3%3%-0.26+0.722026-01-02 → 2026-08-30
tmax12Znearest30d27 1 QC6.88 [5.89, 7.63]1.59-6.88 [-7.63, -5.89]7.19 [6.35, 7.82]4% [0%, 12%]4%4%-0.18+0.732026-08-02 → 2026-08-30
tmax12Znearest90d27 1 QC6.88 [5.72, 7.62]1.59-6.88 [-7.62, -5.72]7.19 [6.20, 7.81]4% [0%, 12%]4%4%-0.18+0.732026-08-02 → 2026-08-30
tmax12Znearest365d32 1 QC7.07 [6.16, 7.85]1.58-7.07 [-7.85, -6.16]7.37 [6.57, 8.04]3% [0%, 10%]3%3%-0.27+0.722026-01-02 → 2026-08-30
tmax12Znearestall32 1 QC7.07 [5.91, 7.79]1.58-7.07 [-7.79, -5.91]7.37 [6.37, 7.99]3% [0%, 11%]3%3%-0.27+0.722026-01-02 → 2026-08-30
tmin00Zbilinear30d27 1 QC3.09 [2.10, 4.11]2.27+2.51 [1.61, 3.35]3.77 [2.70, 4.57]19% [4%, 33%]41%52%+0.27+0.472026-08-02 → 2026-08-30
tmin00Zbilinear90d27 1 QC3.09 [2.18, 4.36]2.27+2.51 [1.52, 3.63]3.77 [2.82, 4.73]19% [0%, 31%]41%52%+0.27+0.472026-08-02 → 2026-08-30
tmin00Zbilinear365d33 1 QC3.49 [2.41, 4.78]2.47+2.98 [1.88, 4.29]4.27 [3.08, 5.45]18% [6%, 30%]36%45%+0.20+0.432026-01-02 → 2026-08-30
tmin00Zbilinearall33 1 QC3.49 [2.33, 4.90]2.47+2.98 [1.86, 4.35]4.27 [2.99, 5.53]18% [4%, 30%]36%45%+0.20+0.432026-01-02 → 2026-08-30
tmin00Znearest30d27 1 QC2.98 [2.05, 3.97]2.30+2.24 [1.26, 3.15]3.64 [2.56, 4.47]19% [4%, 33%]41%56%+0.30+0.462026-08-02 → 2026-08-30
tmin00Znearest90d27 1 QC2.98 [2.12, 4.18]2.30+2.24 [1.19, 3.37]3.64 [2.66, 4.64]19% [0%, 31%]41%56%+0.30+0.462026-08-02 → 2026-08-30
tmin00Znearest365d33 1 QC3.39 [2.34, 4.64]2.52+2.73 [1.57, 4.08]4.13 [2.96, 5.27]18% [6%, 30%]36%48%+0.22+0.422026-01-02 → 2026-08-30
tmin00Znearestall33 1 QC3.39 [2.30, 4.82]2.52+2.73 [1.52, 4.13]4.13 [2.82, 5.36]18% [4%, 29%]36%48%+0.22+0.422026-01-02 → 2026-08-30
tmin12Zbilinear30d27 1 QC2.42 [1.53, 3.45]2.28+1.46 [0.65, 2.32]3.16 [2.16, 4.00]30% [5%, 50%]48%63%+0.43+0.462026-08-02 → 2026-08-30
tmin12Zbilinear90d27 1 QC2.42 [1.63, 3.62]2.28+1.46 [0.55, 2.63]3.16 [2.26, 4.15]30% [0%, 50%]48%63%+0.43+0.462026-08-02 → 2026-08-30
tmin12Zbilinear365d32 1 QC2.82 [1.80, 4.18]2.50+1.97 [0.88, 3.55]3.69 [2.54, 4.98]28% [6%, 46%]44%56%+0.36+0.432026-01-02 → 2026-08-30
tmin12Zbilinearall32 1 QC2.82 [1.78, 4.33]2.50+1.97 [0.88, 3.56]3.69 [2.42, 5.04]28% [4%, 46%]44%56%+0.36+0.432026-01-02 → 2026-08-30
tmin12Znearest30d27 1 QC2.38 [1.51, 3.44]2.31+1.23 [0.35, 2.16]3.10 [2.04, 4.02]33% [7%, 57%]56%67%+0.44+0.462026-08-02 → 2026-08-30
tmin12Znearest90d27 1 QC2.38 [1.61, 3.65]2.31+1.23 [0.28, 2.47]3.10 [2.12, 4.18]33% [0%, 57%]56%67%+0.44+0.462026-08-02 → 2026-08-30
tmin12Znearest365d32 1 QC2.81 [1.79, 4.25]2.59+1.77 [0.59, 3.38]3.64 [2.43, 4.97]28% [0%, 53%]50%59%+0.37+0.412026-01-02 → 2026-08-30
tmin12Znearestall32 1 QC2.81 [1.75, 4.39]2.59+1.77 [0.60, 3.44]3.64 [2.30, 5.02]28% [0%, 52%]50%59%+0.37+0.412026-01-02 → 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 GraphCast (IFS init) at KDEN, lead day 1, 00Z bilinear tmax+20+100-10-202026-08-02: -5.45 °F2026-08-03: -5.45 °F2026-08-04: -1.72 °F2026-08-05: -5.51 °F2026-08-06: -6.49 °F2026-08-07: -6.09 °F2026-08-08: -6.45 °F2026-08-09: -4.52 °F2026-08-10: -3.98 °F2026-08-11: -5.88 °F2026-08-12: -8.3 °F2026-08-13: -6.54 °F2026-08-14: -10.66 °F2026-08-15: -5.8 °F2026-08-16: -5.56 °F2026-08-17: -8.08 °F2026-08-18: -4.26 °F2026-08-19: -7.33 °F2026-08-20: -5.21 °F2026-08-21: -8.5 °F2026-08-22: -4.98 °F2026-08-23: -8.19 °F2026-08-24: -5.02 °F2026-08-25: -2.21 °F2026-08-26: -7.03 °F2026-08-29: -6.53 °F2026-08-30: -4.08 °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
2026-08-30-4.08
2026-08-29-6.53
2026-08-28—
2026-08-27—
2026-08-26-7.03
2026-08-25-2.21
2026-08-24-5.02
2026-08-23-8.19
2026-08-22-4.98
2026-08-21-8.50
2026-08-20-5.21
2026-08-19-7.33
2026-08-18-4.26
2026-08-17-8.08
2026-08-16-5.56
2026-08-15-5.80
2026-08-14-10.66
2026-08-13-6.54
2026-08-12-8.30
2026-08-11-5.88
2026-08-10-3.98
2026-08-09-4.52
2026-08-08-6.45
2026-08-07-6.09
2026-08-06-6.49
2026-08-05-5.51
2026-08-04-1.72
2026-08-03-5.45
2026-08-02-5.45

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KDEN, lead day 1-20 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: 5 days-8 to -6 °F: 10 days-6 to -4 °F: 13 days-4 to -2 °F: 2 days-2 to 0 °F: 1 day0 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| 6.09 · P90 |e| 8.46 °F-200+20 °Fn = 33 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
-10.00-8.005
-8.00-6.0010
-6.00-4.0013
-4.00-2.002
-2.00+0.001
+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
2026-08275.92 -5.92
2026-0167.78 -7.78

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-02 → 2026-08-30 33
GraphCast (IFS init)2026-01-02 → 2026-08-30 33
GraphCast (IFS init)2026-01-02 → 2026-08-30 32
GraphCast (IFS init)2026-01-02 → 2026-08-30 32

Compared with other models

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

Other modelCommon days MAE difference °FDistinguishable
ECMWF AIFS Single 27 +2.14 [1.52, 2.59] yes
Aurora (GFS init) 1 -0.93 [-0.93, -0.93] yes
Aurora (IFS init) 2 +0.28 [-0.01, 0.56] no
FourCastNet v2 (GFS init) 1 -0.07 [-0.07, -0.07] yes
FourCastNet v2 (IFS init) 2 -0.25 [-0.65, 0.15] no
NCEP GFS 27 +2.34 [0.89, 3.40] yes
GraphCast (GFS init) 1 +1.02 [1.02, 1.02] yes
ECMWF IFS HRES 20 +2.55 [1.83, 3.18] yes
Pangu-Weather (GFS init) 1 +3.82 [3.82, 3.82] yes
Pangu-Weather (IFS init) 2 +3.50 [3.13, 3.87] yes
Persistence (baseline) 27 +0.10 [-3.39, 1.97] no

Cite this page

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

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KDEN (Denver Intl), model graphcast_ifs, 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/KDEN/model/graphcast_ifs/lead/1/

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