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

Denver Intl · GraphCast (IFS init) · lead day 6

KDEN · graphcast_ifs · lead 6

Target day = initialization date + 6 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
tmax00Zbilinear30d24 1 QC7.63 [6.29, 8.70]3.18-7.63 [-8.70, -6.29]8.58 [7.00, 9.64]0% [0%, 0%]8%12%-0.02+0.582026-08-07 → 2026-08-30
tmax00Zbilinear90d24 1 QC7.63 [6.11, 8.89]3.18-7.63 [-8.89, -6.11]8.58 [6.56, 9.75]0% [0%, 0%]8%12%-0.02+0.582026-08-07 → 2026-08-30
tmax00Zbilinear365d30 1 QC7.77 [6.42, 9.19]3.66-7.62 [-9.10, -6.04]8.84 [7.32, 10.14]3% [0%, 12%]10%17%+0.14+0.582026-01-07 → 2026-08-30
tmax00Zbilinearall30 1 QC7.77 [6.44, 9.04]3.66-7.62 [-8.96, -6.20]8.84 [7.20, 10.08]3% [0%, 12%]10%17%+0.14+0.582026-01-07 → 2026-08-30
tmax00Znearest30d24 1 QC7.65 [6.38, 8.72]3.12-7.65 [-8.72, -6.38]8.57 [7.03, 9.59]0% [0%, 0%]8%12%-0.02+0.582026-08-07 → 2026-08-30
tmax00Znearest90d24 1 QC7.65 [6.21, 8.91]3.12-7.65 [-8.91, -6.21]8.57 [6.60, 9.72]0% [0%, 0%]8%12%-0.02+0.582026-08-07 → 2026-08-30
tmax00Znearest365d30 1 QC7.77 [6.46, 9.11]3.54-7.59 [-8.97, -6.05]8.76 [7.26, 9.94]0% [0%, 0%]10%17%+0.14+0.592026-01-07 → 2026-08-30
tmax00Znearestall30 1 QC7.77 [6.48, 8.97]3.54-7.59 [-8.95, -6.23]8.76 [7.19, 9.90]0% [0%, 0%]10%17%+0.14+0.592026-01-07 → 2026-08-30
tmax12Zbilinear30d24 1 QC7.57 [6.55, 8.37]3.14-7.57 [-8.37, -6.55]8.41 [7.33, 9.23]4% [0%, 12%]8%17%-0.01+0.582026-08-07 → 2026-08-30
tmax12Zbilinear90d24 1 QC7.57 [6.38, 8.48]3.14-7.57 [-8.48, -6.38]8.41 [7.07, 9.29]4% [0%, 11%]8%17%-0.01+0.582026-08-07 → 2026-08-30
tmax12Zbilinear365d29 1 QC7.90 [6.78, 9.28]3.70-7.74 [-8.98, -6.64]9.15 [7.64, 11.12]3% [0%, 10%]7%17%+0.13+0.572026-01-07 → 2026-08-30
tmax12Zbilinearall29 1 QC7.90 [6.71, 9.24]3.70-7.74 [-8.82, -6.47]9.15 [7.51, 11.14]3% [0%, 10%]7%17%+0.13+0.572026-01-07 → 2026-08-30
tmax12Znearest30d24 1 QC7.61 [6.58, 8.42]3.08-7.61 [-8.42, -6.58]8.43 [7.37, 9.27]4% [0%, 12%]8%17%-0.02+0.592026-08-07 → 2026-08-30
tmax12Znearest90d24 1 QC7.61 [6.45, 8.53]3.08-7.61 [-8.53, -6.45]8.43 [7.20, 9.34]4% [0%, 11%]8%17%-0.02+0.592026-08-07 → 2026-08-30
tmax12Znearest365d29 1 QC7.95 [6.80, 9.31]3.64-7.80 [-9.03, -6.72]9.20 [7.68, 11.18]3% [0%, 10%]7%17%+0.13+0.582026-01-07 → 2026-08-30
tmax12Znearestall29 1 QC7.95 [6.74, 9.29]3.64-7.80 [-8.89, -6.55]9.20 [7.55, 11.20]3% [0%, 10%]7%17%+0.13+0.582026-01-07 → 2026-08-30
tmin00Zbilinear30d24 1 QC2.63 [2.21, 3.06]1.96+1.77 [0.98, 2.70]2.93 [2.49, 3.29]12% [0%, 24%]38%54%+0.52+0.642026-08-07 → 2026-08-30
tmin00Zbilinear90d24 1 QC2.63 [2.10, 3.12]1.96+1.77 [0.83, 2.85]2.93 [2.39, 3.32]12% [0%, 25%]38%54%+0.52+0.642026-08-07 → 2026-08-30
tmin00Zbilinear365d30 1 QC2.69 [2.11, 3.22]2.03+1.99 [1.09, 3.03]3.19 [2.47, 3.85]17% [6%, 30%]43%57%+0.57+0.682026-01-07 → 2026-08-30
tmin00Zbilinearall30 1 QC2.69 [2.17, 3.14]2.03+1.99 [1.12, 3.00]3.19 [2.51, 3.87]17% [4%, 31%]43%57%+0.57+0.682026-01-07 → 2026-08-30
tmin00Znearest30d24 1 QC2.46 [2.16, 2.81]1.93+1.46 [0.68, 2.39]2.72 [2.41, 3.02]12% [0%, 23%]38%62%+0.55+0.652026-08-07 → 2026-08-30
tmin00Znearest90d24 1 QC2.46 [2.10, 2.87]1.93+1.46 [0.56, 2.62]2.72 [2.35, 3.05]12% [0%, 24%]38%62%+0.55+0.652026-08-07 → 2026-08-30
tmin00Znearest365d30 1 QC2.54 [2.07, 3.03]2.02+1.68 [0.81, 2.76]3.01 [2.35, 3.73]20% [5%, 38%]43%63%+0.59+0.682026-01-07 → 2026-08-30
tmin00Znearestall30 1 QC2.54 [2.10, 2.97]2.02+1.68 [0.79, 2.73]3.01 [2.40, 3.75]20% [5%, 40%]43%63%+0.59+0.682026-01-07 → 2026-08-30
tmin12Zbilinear30d24 1 QC2.26 [1.85, 2.66]1.79+1.38 [0.87, 1.94]2.63 [2.30, 2.93]25% [5%, 44%]42%58%+0.59+0.682026-08-07 → 2026-08-30
tmin12Zbilinear90d24 1 QC2.26 [1.85, 2.70]1.79+1.38 [0.86, 2.08]2.63 [2.29, 2.96]25% [0%, 45%]42%58%+0.59+0.682026-08-07 → 2026-08-30
tmin12Zbilinear365d29 1 QC2.39 [1.93, 2.92]1.90+1.62 [1.02, 2.45]2.89 [2.37, 3.52]28% [9%, 45%]41%55%+0.63+0.702026-01-07 → 2026-08-30
tmin12Zbilinearall29 1 QC2.39 [1.92, 2.89]1.90+1.62 [1.00, 2.50]2.89 [2.38, 3.52]28% [7%, 48%]41%55%+0.63+0.702026-01-07 → 2026-08-30
tmin12Znearest30d24 1 QC2.12 [1.75, 2.47]1.77+1.10 [0.62, 1.67]2.48 [2.15, 2.77]29% [15%, 48%]46%75%+0.61+0.682026-08-07 → 2026-08-30
tmin12Znearest90d24 1 QC2.12 [1.73, 2.50]1.77+1.10 [0.62, 1.86]2.48 [2.12, 2.78]29% [15%, 50%]46%75%+0.61+0.682026-08-07 → 2026-08-30
tmin12Znearest365d29 1 QC2.25 [1.82, 2.75]1.87+1.34 [0.78, 2.16]2.72 [2.23, 3.34]31% [17%, 47%]45%72%+0.65+0.712026-01-07 → 2026-08-30
tmin12Znearestall29 1 QC2.25 [1.77, 2.71]1.87+1.34 [0.73, 2.24]2.72 [2.18, 3.36]31% [17%, 50%]45%72%+0.65+0.712026-01-07 → 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 6, 00Z bilinear tmax+20+100-10-202026-08-07: -3.62 °F2026-08-08: -8.39 °F2026-08-09: -3.14 °F2026-08-10: -14.87 °F2026-08-11: -10.81 °F2026-08-12: -8.44 °F2026-08-13: -10.99 °F2026-08-14: -13.14 °F2026-08-15: -1.3 °F2026-08-16: -2.58 °F2026-08-17: -7.44 °F2026-08-18: -3.59 °F2026-08-19: -9.06 °F2026-08-20: -13.39 °F2026-08-21: -14.39 °F2026-08-22: -7.36 °F2026-08-23: -9.85 °F2026-08-24: -5.04 °F2026-08-25: -1.29 °F2026-08-26: -6.73 °F2026-08-27: -7.48 °F2026-08-28: -7.21 °F2026-08-29: -8.72 °F2026-08-30: -4.19 °F2026-08-072026-08-30°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 (24 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-4.19
2026-08-29-8.72
2026-08-28-7.21
2026-08-27-7.48
2026-08-26-6.73
2026-08-25-1.29
2026-08-24-5.04
2026-08-23-9.85
2026-08-22-7.36
2026-08-21-14.39
2026-08-20-13.39
2026-08-19-9.06
2026-08-18-3.59
2026-08-17-7.44
2026-08-16-2.58
2026-08-15-1.30
2026-08-14-13.14
2026-08-13-10.99
2026-08-12-8.44
2026-08-11-10.81
2026-08-10-14.87
2026-08-09-3.14
2026-08-08-8.39
2026-08-07-3.62

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KDEN, lead day 6-20 to -18 °F: 0 days-18 to -16 °F: 0 days-16 to -14 °F: 2 days-14 to -12 °F: 4 days-12 to -10 °F: 3 days-10 to -8 °F: 6 days-8 to -6 °F: 5 days-6 to -4 °F: 2 days-4 to -2 °F: 4 days-2 to 0 °F: 3 days0 to 2 °F: 0 days2 to 4 °F: 1 day4 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| 7.92 · P90 |e| 13.5 °F-200+20 °Fn = 30 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
-16.00-14.002
-14.00-12.004
-12.00-10.003
-10.00-8.006
-8.00-6.005
-6.00-4.002
-4.00-2.004
-2.00+0.003
+0.00+2.000
+2.00+4.001
+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
2026-08247.63 -7.63
2026-0168.36 -7.58

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-07 → 2026-08-30 30
GraphCast (IFS init)2026-01-07 → 2026-08-30 30
GraphCast (IFS init)2026-01-07 → 2026-08-30 29
GraphCast (IFS init)2026-01-07 → 2026-08-30 29

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 24 +2.05 [0.64, 3.48] yes
NCEP GFS 24 +3.60 [1.63, 5.59] yes
ECMWF IFS HRES 19 +2.14 [-0.94, 3.92] no
Persistence (baseline) 24 +0.13 [-2.19, 2.62] no

Cite this page

ShortCastCheck, KDEN graphcast_ifs lead 6, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KDEN/model/graphcast_ifs/lead/6/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KDEN (Denver Intl), model graphcast_ifs, lead day 6. 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/6/

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