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

Denver Intl · GraphCast (IFS init) · lead day 0

KDEN · graphcast_ifs · lead 0

Target day = initialization date + 0 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, 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
tmax00Zbilinear30d28 1 QC5.53 [4.77, 6.32]1.50-5.53 [-6.32, -4.77]5.81 [5.00, 6.53]0% [0%, 0%]0%7%——2026-08-01 → 2026-08-30
tmax00Zbilinear90d28 1 QC5.53 [4.66, 6.22]1.50-5.53 [-6.22, -4.66]5.81 [4.85, 6.46]0% [0%, 0%]0%7%——2026-08-01 → 2026-08-30
tmax00Zbilinear365d34 1 QC5.98 [5.05, 7.19]1.68-5.98 [-7.19, -5.05]6.33 [5.32, 7.49]0% [0%, 0%]0%6%——2026-01-01 → 2026-08-30
tmax00Zbilinearall34 1 QC5.98 [4.95, 6.96]1.68-5.98 [-6.96, -4.95]6.33 [5.24, 7.30]0% [0%, 0%]0%6%——2026-01-01 → 2026-08-30
tmax00Znearest30d28 1 QC5.60 [4.72, 6.44]1.48-5.60 [-6.44, -4.72]5.87 [4.98, 6.61]0% [0%, 0%]0%7%——2026-08-01 → 2026-08-30
tmax00Znearest90d28 1 QC5.60 [4.60, 6.35]1.48-5.60 [-6.35, -4.60]5.87 [4.84, 6.55]0% [0%, 0%]0%7%——2026-08-01 → 2026-08-30
tmax00Znearest365d34 1 QC6.01 [5.05, 7.14]1.64-6.01 [-7.14, -5.05]6.33 [5.30, 7.43]0% [0%, 0%]0%6%——2026-01-01 → 2026-08-30
tmax00Znearestall34 1 QC6.01 [4.96, 6.93]1.64-6.01 [-6.93, -4.96]6.33 [5.20, 7.23]0% [0%, 0%]0%6%——2026-01-01 → 2026-08-30
tmin00Zbilinear30d28 1 QC2.82 [2.11, 3.43]1.79+2.42 [1.70, 3.13]3.31 [2.53, 3.89]18% [7%, 28%]32%64%——2026-08-01 → 2026-08-30
tmin00Zbilinear90d28 1 QC2.82 [2.14, 3.58]1.79+2.42 [1.50, 3.48]3.31 [2.54, 3.94]18% [4%, 29%]32%64%——2026-08-01 → 2026-08-30
tmin00Zbilinear365d34 1 QC3.22 [2.34, 4.43]2.17+2.80 [1.83, 4.05]3.99 [2.81, 5.39]18% [7%, 27%]32%59%——2026-01-01 → 2026-08-30
tmin00Zbilinearall34 1 QC3.22 [2.31, 4.37]2.17+2.80 [1.79, 4.03]3.99 [2.74, 5.35]18% [7%, 26%]32%59%——2026-01-01 → 2026-08-30
tmin00Znearest30d28 1 QC2.65 [1.85, 3.31]1.84+2.15 [1.38, 2.89]3.15 [2.35, 3.72]18% [3%, 37%]39%64%——2026-08-01 → 2026-08-30
tmin00Znearest90d28 1 QC2.65 [1.90, 3.45]1.84+2.15 [1.22, 3.22]3.15 [2.34, 3.77]18% [0%, 38%]39%64%——2026-08-01 → 2026-08-30
tmin00Znearest365d34 1 QC3.11 [2.15, 4.46]2.24+2.63 [1.58, 4.02]3.92 [2.67, 5.42]18% [3%, 36%]38%59%——2026-01-01 → 2026-08-30
tmin00Znearestall34 1 QC3.11 [2.07, 4.40]2.24+2.63 [1.57, 3.91]3.92 [2.57, 5.39]18% [0%, 36%]38%59%——2026-01-01 → 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 0, 00Z bilinear tmax+10+50-5-102026-08-01: -6.03 °F2026-08-02: -3.96 °F2026-08-03: -4.7 °F2026-08-04: -2.67 °F2026-08-05: -4.52 °F2026-08-06: -5.5 °F2026-08-07: -4.88 °F2026-08-08: -6.6 °F2026-08-09: -3.8 °F2026-08-10: -3.32 °F2026-08-11: -4.93 °F2026-08-12: -8.2 °F2026-08-13: -7.78 °F2026-08-14: -8.32 °F2026-08-15: -5.71 °F2026-08-16: -5.52 °F2026-08-17: -6.88 °F2026-08-18: -5.95 °F2026-08-19: -7.41 °F2026-08-20: -3.47 °F2026-08-21: -8.92 °F2026-08-22: -6.41 °F2026-08-23: -6.55 °F2026-08-24: -3.65 °F2026-08-25: -3.43 °F2026-08-28: -6.82 °F2026-08-29: -6.85 °F2026-08-30: -2.18 °F2026-08-012026-08-30°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 (30 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-2.18
2026-08-29-6.85
2026-08-28-6.82
2026-08-27—
2026-08-26—
2026-08-25-3.43
2026-08-24-3.65
2026-08-23-6.55
2026-08-22-6.41
2026-08-21-8.92
2026-08-20-3.47
2026-08-19-7.41
2026-08-18-5.95
2026-08-17-6.88
2026-08-16-5.52
2026-08-15-5.71
2026-08-14-8.32
2026-08-13-7.78
2026-08-12-8.20
2026-08-11-4.93
2026-08-10-3.32
2026-08-09-3.80
2026-08-08-6.60
2026-08-07-4.88
2026-08-06-5.50
2026-08-05-4.52
2026-08-04-2.67
2026-08-03-4.70
2026-08-02-3.96
2026-08-01-6.03

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KDEN, lead day 0-20 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: 4 days-8 to -6 °F: 11 days-6 to -4 °F: 9 days-4 to -2 °F: 8 days-2 to 0 °F: 0 days0 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| 5.99 · P90 |e| 8.74 °F-200+20 °Fn = 34 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
-10.00-8.004
-8.00-6.0011
-6.00-4.009
-4.00-2.008
-2.00+0.000
+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
2026-08285.53 -5.53
2026-0168.08 -8.08

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-01 → 2026-08-30 34
GraphCast (IFS init)2026-01-01 → 2026-08-30 34

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 28 +1.78 [1.34, 2.30] yes
Aurora (GFS init) 2 -1.57 [-2.24, -0.90] yes
Aurora (IFS init) 3 +0.49 [-0.08, 1.62] no
FourCastNet v2 (GFS init) 2 -2.87 [-3.20, -2.55] yes
FourCastNet v2 (IFS init) 3 -0.22 [-1.75, 1.17] no
NCEP GFS 28 +1.76 [0.65, 2.75] yes
GraphCast (GFS init) 2 -0.76 [-0.91, -0.60] yes
ECMWF IFS HRES 23 +2.59 [1.77, 3.29] yes
Pangu-Weather (GFS init) 2 +0.38 [0.09, 0.66] yes
Pangu-Weather (IFS init) 3 +2.98 [1.76, 3.88] yes

Cite this page

ShortCastCheck, KDEN graphcast_ifs lead 0, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KDEN/model/graphcast_ifs/lead/0/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KDEN (Denver Intl), model graphcast_ifs, lead day 0. 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/0/

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

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