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

Trenton Mercer · GraphCast (IFS init) · lead day 7

KTTN · graphcast_ifs · lead 7

Target day = initialization date + 7 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
tmax00Zbilinear30d23 1 QC2.37 [1.94, 2.87]2.00-1.36 [-1.92, -0.91]2.90 [2.27, 3.53]17% [5%, 30%]43%74%+0.35+0.412026-08-08 → 2026-08-30
tmax00Zbilinear90d23 1 QC2.37 [1.91, 2.87]2.00-1.36 [-1.94, -0.94]2.90 [2.24, 3.55]17% [0%, 32%]43%74%+0.35+0.412026-08-08 → 2026-08-30
tmax00Zbilinear365d29 1 QC2.57 [1.98, 3.24]2.39-0.93 [-1.83, 0.19]3.24 [2.37, 4.07]21% [10%, 33%]45%69%+0.56+0.602026-01-08 → 2026-08-30
tmax00Zbilinearall29 1 QC2.57 [2.00, 3.26]2.39-0.93 [-1.76, 0.27]3.24 [2.38, 4.11]21% [9%, 33%]45%69%+0.56+0.602026-01-08 → 2026-08-30
tmax00Znearest30d23 1 QC2.33 [1.91, 2.83]1.99-1.22 [-1.78, -0.79]2.83 [2.19, 3.48]22% [13%, 33%]43%74%+0.36+0.412026-08-08 → 2026-08-30
tmax00Znearest90d23 1 QC2.33 [1.84, 2.84]1.99-1.22 [-1.77, -0.81]2.83 [2.14, 3.50]22% [12%, 35%]43%74%+0.36+0.412026-08-08 → 2026-08-30
tmax00Znearest365d29 1 QC2.56 [1.95, 3.25]2.44-0.74 [-1.70, 0.45]3.23 [2.30, 4.12]28% [15%, 45%]45%69%+0.56+0.592026-01-08 → 2026-08-30
tmax00Znearestall29 1 QC2.56 [1.96, 3.26]2.44-0.74 [-1.62, 0.59]3.23 [2.30, 4.13]28% [15%, 46%]45%69%+0.56+0.592026-01-08 → 2026-08-30
tmax12Zbilinear30d23 1 QC2.11 [1.60, 2.61]1.97-1.31 [-2.27, -0.46]2.71 [2.11, 3.29]30% [19%, 46%]52%70%+0.42+0.422026-08-08 → 2026-08-30
tmax12Zbilinear90d23 1 QC2.11 [1.57, 2.58]1.97-1.31 [-2.44, -0.34]2.71 [2.05, 3.34]30% [17%, 50%]52%70%+0.42+0.422026-08-08 → 2026-08-30
tmax12Zbilinear365d28 1 QC2.39 [1.73, 3.20]2.36-0.45 [-1.95, 1.70]3.21 [2.16, 4.30]32% [21%, 48%]50%68%+0.59+0.602026-01-08 → 2026-08-30
tmax12Zbilinearall28 1 QC2.39 [1.69, 3.31]2.36-0.45 [-1.95, 1.87]3.21 [2.15, 4.48]32% [22%, 50%]50%68%+0.59+0.602026-01-08 → 2026-08-30
tmax12Znearest30d23 1 QC2.08 [1.59, 2.55]1.98-1.18 [-2.15, -0.32]2.66 [2.07, 3.20]35% [23%, 48%]57%70%+0.43+0.412026-08-08 → 2026-08-30
tmax12Znearest90d23 1 QC2.08 [1.55, 2.53]1.98-1.18 [-2.30, -0.21]2.66 [2.00, 3.25]35% [20%, 50%]57%70%+0.43+0.412026-08-08 → 2026-08-30
tmax12Znearest365d28 1 QC2.40 [1.69, 3.32]2.39-0.29 [-1.82, 1.91]3.26 [2.12, 4.50]36% [25%, 50%]54%68%+0.59+0.592026-01-08 → 2026-08-30
tmax12Znearestall28 1 QC2.40 [1.69, 3.43]2.39-0.29 [-1.80, 2.11]3.26 [2.13, 4.67]36% [25%, 50%]54%68%+0.59+0.592026-01-08 → 2026-08-30
tmin00Zbilinear30d23 1 QC4.32 [3.39, 5.33]2.95+3.85 [2.47, 5.29]5.11 [4.20, 5.97]13% [0%, 29%]26%39%-0.03+0.212026-08-08 → 2026-08-30
tmin00Zbilinear90d23 1 QC4.32 [3.36, 5.45]2.95+3.85 [2.35, 5.45]5.11 [4.14, 6.04]13% [0%, 29%]26%39%-0.03+0.212026-08-08 → 2026-08-30
tmin00Zbilinear365d29 1 QC4.87 [3.68, 6.47]2.99+4.50 [2.89, 6.46]5.72 [4.43, 7.09]10% [0%, 25%]21%34%+0.09+0.442026-01-08 → 2026-08-30
tmin00Zbilinearall29 1 QC4.87 [3.69, 6.56]2.99+4.50 [2.88, 6.56]5.72 [4.52, 7.18]10% [0%, 24%]21%34%+0.09+0.442026-01-08 → 2026-08-30
tmin00Znearest30d23 1 QC4.48 [3.53, 5.57]2.95+4.07 [2.70, 5.52]5.28 [4.33, 6.18]17% [5%, 31%]26%35%-0.07+0.212026-08-08 → 2026-08-30
tmin00Znearest90d23 1 QC4.48 [3.47, 5.67]2.95+4.07 [2.58, 5.67]5.28 [4.26, 6.26]17% [0%, 30%]26%35%-0.07+0.212026-08-08 → 2026-08-30
tmin00Znearest365d29 1 QC5.05 [3.81, 6.71]2.99+4.73 [3.12, 6.71]5.90 [4.57, 7.30]14% [0%, 27%]21%28%+0.06+0.442026-01-08 → 2026-08-30
tmin00Znearestall29 1 QC5.05 [3.81, 6.79]2.99+4.73 [3.10, 6.79]5.90 [4.65, 7.39]14% [0%, 26%]21%28%+0.06+0.442026-01-08 → 2026-08-30
tmin12Zbilinear30d23 1 QC4.07 [2.74, 5.40]2.02+3.94 [2.45, 5.40]4.71 [3.17, 6.02]4% [0%, 12%]26%39%+0.03+0.462026-08-08 → 2026-08-30
tmin12Zbilinear90d23 1 QC4.07 [2.72, 5.65]2.02+3.94 [2.49, 5.65]4.71 [3.12, 6.25]4% [0%, 13%]26%39%+0.03+0.462026-08-08 → 2026-08-30
tmin12Zbilinear365d28 1 QC4.43 [2.91, 6.11]2.47+4.32 [2.69, 6.03]5.30 [3.34, 7.10]7% [0%, 18%]25%39%+0.19+0.552026-01-08 → 2026-08-30
tmin12Zbilinearall28 1 QC4.43 [2.95, 6.11]2.47+4.32 [2.66, 6.08]5.30 [3.49, 7.12]7% [0%, 19%]25%39%+0.19+0.552026-01-08 → 2026-08-30
tmin12Znearest30d23 1 QC4.27 [2.93, 5.62]2.02+4.16 [2.67, 5.61]4.90 [3.35, 6.22]0% [0%, 0%]17%35%-0.02+0.462026-08-08 → 2026-08-30
tmin12Znearest90d23 1 QC4.27 [2.91, 5.87]2.02+4.16 [2.72, 5.87]4.90 [3.32, 6.45]0% [0%, 0%]17%35%-0.02+0.462026-08-08 → 2026-08-30
tmin12Znearest365d28 1 QC4.63 [3.10, 6.25]2.47+4.53 [2.91, 6.23]5.49 [3.55, 7.31]4% [0%, 14%]18%36%+0.16+0.552026-01-08 → 2026-08-30
tmin12Znearestall28 1 QC4.63 [3.12, 6.31]2.47+4.53 [2.88, 6.30]5.49 [3.65, 7.34]4% [0%, 16%]18%36%+0.16+0.552026-01-08 → 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 KTTN, lead day 7, 00Z bilinear tmax+10+50-5-102026-08-08: -1.94 °F2026-08-09: -4.42 °F2026-08-10: +0.38 °F2026-08-11: +0.49 °F2026-08-12: -2.24 °F2026-08-13: +1.15 °F2026-08-14: -2.25 °F2026-08-15: -7.3 °F2026-08-16: +4.65 °F2026-08-17: +0.16 °F2026-08-18: -3.58 °F2026-08-19: -2.22 °F2026-08-20: +1.83 °F2026-08-21: -3.34 °F2026-08-22: -1.3 °F2026-08-23: +0.43 °F2026-08-24: -4.64 °F2026-08-25: -1.32 °F2026-08-26: -2.42 °F2026-08-27: +2.55 °F2026-08-28: -2.21 °F2026-08-29: -1.01 °F2026-08-30: -2.7 °F2026-08-082026-08-30°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 (23 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-2.70
2026-08-29-1.01
2026-08-28-2.21
2026-08-27+2.55
2026-08-26-2.42
2026-08-25-1.32
2026-08-24-4.64
2026-08-23+0.43
2026-08-22-1.30
2026-08-21-3.34
2026-08-20+1.83
2026-08-19-2.22
2026-08-18-3.58
2026-08-17+0.16
2026-08-16+4.65
2026-08-15-7.30
2026-08-14-2.25
2026-08-13+1.15
2026-08-12-2.24
2026-08-11+0.49
2026-08-10+0.38
2026-08-09-4.42
2026-08-08-1.94

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KTTN, lead day 7-10 to -9 °F: 0 days-9 to -8 °F: 0 days-8 to -7 °F: 1 day-7 to -6 °F: 1 day-6 to -5 °F: 0 days-5 to -4 °F: 2 days-4 to -3 °F: 2 days-3 to -2 °F: 6 days-2 to -1 °F: 5 days-1 to 0 °F: 1 day0 to 1 °F: 5 days1 to 2 °F: 2 days2 to 3 °F: 1 day3 to 4 °F: 0 days4 to 5 °F: 1 day5 to 6 °F: 1 day6 to 7 °F: 1 day7 to 8 °F: 0 days8 to 9 °F: 0 days9 to 10 °F: 0 daysdashed: P50 |e| 2.22 · P90 |e| 5.54 °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
-8.00-7.001
-7.00-6.001
-6.00-5.000
-5.00-4.002
-4.00-3.002
-3.00-2.006
-2.00-1.005
-1.00+0.001
+0.00+1.005
+1.00+2.002
+2.00+3.001
+3.00+4.000
+4.00+5.001
+5.00+6.001
+6.00+7.001
+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
2026-08232.37 -1.36
2026-0163.35 +0.71

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-08 → 2026-08-30 29
GraphCast (IFS init)2026-01-08 → 2026-08-30 29
GraphCast (IFS init)2026-01-08 → 2026-08-30 28
GraphCast (IFS init)2026-01-08 → 2026-08-30 28

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 23 +0.78 [0.29, 1.37] yes
NCEP GFS 23 -0.92 [-2.10, 0.44] no
ECMWF IFS HRES 18 -0.19 [-2.17, 0.55] no
Persistence (baseline) 23 -1.28 [-2.12, 0.11] no

Cite this page

ShortCastCheck, KTTN graphcast_ifs lead 7, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KTTN/model/graphcast_ifs/lead/7/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KTTN (Trenton Mercer), model graphcast_ifs, lead day 7. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KTTN/model/graphcast_ifs/lead/7/

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