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

Minneapolis-St Paul · GraphCast (IFS init) · lead day 8

KMSP · graphcast_ifs · lead 8

Target day = initialization date + 8 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
tmax00Zbilinear30d22 1 QC6.31 [4.36, 8.66]3.84-6.05 [-8.65, -3.82]7.66 [5.54, 9.49]9% [0%, 22%]18%32%-0.95-0.202026-08-09 → 2026-08-30
tmax00Zbilinear90d22 1 QC6.31 [4.20, 8.97]3.84-6.05 [-8.97, -3.74]7.66 [5.41, 9.67]9% [0%, 22%]18%32%-0.95-0.202026-08-09 → 2026-08-30
tmax00Zbilinear365d28 1 QC6.42 [4.63, 8.52]3.61-6.22 [-8.52, -4.17]7.65 [5.87, 9.24]7% [0%, 18%]14%29%-0.28+0.292026-01-09 → 2026-08-30
tmax00Zbilinearall28 1 QC6.42 [4.63, 8.32]3.61-6.22 [-8.32, -4.16]7.65 [5.73, 9.09]7% [0%, 18%]14%29%-0.28+0.292026-01-09 → 2026-08-30
tmax00Znearest30d22 1 QC6.34 [4.37, 8.70]3.80-6.11 [-8.69, -3.89]7.67 [5.52, 9.51]5% [0%, 12%]18%32%-0.96-0.192026-08-09 → 2026-08-30
tmax00Znearest90d22 1 QC6.34 [4.23, 9.02]3.80-6.11 [-9.02, -3.80]7.67 [5.39, 9.72]5% [0%, 13%]18%32%-0.96-0.192026-08-09 → 2026-08-30
tmax00Znearest365d28 1 QC6.40 [4.58, 8.55]3.55-6.22 [-8.55, -4.22]7.61 [5.81, 9.26]4% [0%, 11%]14%25%-0.28+0.302026-01-09 → 2026-08-30
tmax00Znearestall28 1 QC6.40 [4.66, 8.28]3.55-6.22 [-8.28, -4.21]7.61 [5.67, 9.04]4% [0%, 11%]14%25%-0.28+0.302026-01-09 → 2026-08-30
tmax12Zbilinear30d22 1 QC7.69 [5.47, 10.70]4.17-7.41 [-10.67, -4.91]8.87 [6.62, 11.28]5% [0%, 14%]9%18%-1.38-0.302026-08-09 → 2026-08-30
tmax12Zbilinear90d22 1 QC7.69 [5.33, 11.43]4.17-7.41 [-11.43, -4.80]8.87 [6.37, 11.74]5% [0%, 14%]9%18%-1.38-0.302026-08-09 → 2026-08-30
tmax12Zbilinear365d27 1 QC7.36 [5.26, 10.08]3.80-7.13 [-10.07, -4.83]8.45 [6.04, 10.80]4% [0%, 11%]7%19%-0.44+0.262026-01-09 → 2026-08-30
tmax12Zbilinearall27 1 QC7.36 [5.27, 9.79]3.80-7.13 [-9.76, -4.79]8.45 [5.91, 10.41]4% [0%, 11%]7%19%-0.44+0.262026-01-09 → 2026-08-30
tmax12Znearest30d22 1 QC7.72 [5.53, 10.74]4.19-7.45 [-10.70, -4.94]8.90 [6.67, 11.31]5% [0%, 14%]9%18%-1.39-0.312026-08-09 → 2026-08-30
tmax12Znearest90d22 1 QC7.72 [5.35, 11.46]4.19-7.45 [-11.46, -4.83]8.90 [6.40, 11.78]5% [0%, 14%]9%18%-1.39-0.312026-08-09 → 2026-08-30
tmax12Znearest365d27 1 QC7.36 [5.27, 10.12]3.80-7.14 [-10.09, -4.85]8.46 [6.02, 10.81]4% [0%, 11%]7%19%-0.44+0.262026-01-09 → 2026-08-30
tmax12Znearestall27 1 QC7.36 [5.22, 9.78]3.80-7.14 [-9.78, -4.75]8.46 [5.87, 10.44]4% [0%, 11%]7%19%-0.44+0.262026-01-09 → 2026-08-30
tmin00Zbilinear30d22 1 QC5.52 [3.77, 6.95]5.39-1.46 [-6.02, 3.03]7.09 [4.82, 8.41]9% [0%, 24%]27%41%+0.02+0.052026-08-09 → 2026-08-30
tmin00Zbilinear90d22 1 QC5.52 [3.65, 7.09]5.39-1.46 [-6.67, 3.29]7.09 [4.53, 8.44]9% [0%, 25%]27%41%+0.02+0.052026-08-09 → 2026-08-30
tmin00Zbilinear365d28 1 QC5.15 [3.51, 6.57]5.05-1.57 [-5.71, 2.24]6.63 [4.48, 8.05]11% [0%, 25%]29%39%+0.26+0.252026-01-09 → 2026-08-30
tmin00Zbilinearall28 1 QC5.15 [3.56, 6.53]5.05-1.57 [-5.46, 2.30]6.63 [4.45, 8.02]11% [0%, 25%]29%39%+0.26+0.252026-01-09 → 2026-08-30
tmin00Znearest30d22 1 QC5.51 [3.79, 6.99]5.36-1.61 [-6.18, 2.88]7.09 [4.87, 8.40]9% [0%, 24%]27%41%+0.02+0.052026-08-09 → 2026-08-30
tmin00Znearest90d22 1 QC5.51 [3.68, 7.21]5.36-1.61 [-6.86, 3.15]7.09 [4.62, 8.43]9% [0%, 25%]27%41%+0.02+0.052026-08-09 → 2026-08-30
tmin00Znearest365d28 1 QC5.14 [3.50, 6.61]4.99-1.69 [-5.82, 2.12]6.62 [4.48, 7.99]11% [0%, 25%]29%43%+0.26+0.262026-01-09 → 2026-08-30
tmin00Znearestall28 1 QC5.14 [3.55, 6.56]4.99-1.69 [-5.58, 2.14]6.62 [4.47, 8.00]11% [0%, 25%]29%43%+0.26+0.262026-01-09 → 2026-08-30
tmin12Zbilinear30d22 1 QC5.12 [3.60, 7.06]4.94-2.37 [-6.67, 1.46]6.10 [4.25, 7.95]9% [0%, 17%]18%36%+0.09+0.132026-08-09 → 2026-08-30
tmin12Zbilinear90d22 1 QC5.12 [3.57, 7.59]4.94-2.37 [-7.47, 1.52]6.10 [4.24, 8.32]9% [0%, 18%]18%36%+0.09+0.132026-08-09 → 2026-08-30
tmin12Zbilinear365d27 1 QC4.58 [2.87, 6.76]4.50-2.10 [-6.32, 1.14]5.62 [3.51, 7.69]11% [0%, 22%]26%41%+0.30+0.282026-01-09 → 2026-08-30
tmin12Zbilinearall27 1 QC4.58 [2.72, 6.49]4.50-2.10 [-5.80, 1.17]5.62 [3.24, 7.48]11% [0%, 21%]26%41%+0.30+0.282026-01-09 → 2026-08-30
tmin12Znearest30d22 1 QC5.10 [3.53, 7.15]4.88-2.52 [-6.80, 1.25]6.10 [4.13, 8.03]9% [0%, 17%]18%36%+0.10+0.142026-08-09 → 2026-08-30
tmin12Znearest90d22 1 QC5.10 [3.51, 7.79]4.88-2.52 [-7.59, 1.29]6.10 [4.12, 8.43]9% [0%, 18%]18%36%+0.10+0.142026-08-09 → 2026-08-30
tmin12Znearest365d27 1 QC4.58 [2.86, 6.88]4.46-2.22 [-6.45, 0.96]5.63 [3.46, 7.80]11% [0%, 22%]22%41%+0.30+0.282026-01-09 → 2026-08-30
tmin12Znearestall27 1 QC4.58 [2.80, 6.57]4.46-2.22 [-5.88, 1.01]5.63 [3.25, 7.56]11% [0%, 21%]22%41%+0.30+0.282026-01-09 → 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 KMSP, lead day 8, 00Z bilinear tmax+20+100-10-202026-08-09: -8.39 °F2026-08-10: -8.05 °F2026-08-11: -10.76 °F2026-08-12: -13.95 °F2026-08-13: -5.49 °F2026-08-14: -12.19 °F2026-08-15: -4.26 °F2026-08-16: -4.73 °F2026-08-17: -9.53 °F2026-08-18: -2.42 °F2026-08-19: -0.78 °F2026-08-20: -2.94 °F2026-08-21: -5.82 °F2026-08-22: +0.23 °F2026-08-23: +2.56 °F2026-08-24: -11.49 °F2026-08-25: -5.32 °F2026-08-26: -1.84 °F2026-08-27: -1.28 °F2026-08-28: -16.01 °F2026-08-29: -6.38 °F2026-08-30: -4.32 °F2026-08-092026-08-30°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 (22 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-4.32
2026-08-29-6.38
2026-08-28-16.01
2026-08-27-1.28
2026-08-26-1.84
2026-08-25-5.32
2026-08-24-11.49
2026-08-23+2.56
2026-08-22+0.23
2026-08-21-5.82
2026-08-20-2.94
2026-08-19-0.78
2026-08-18-2.42
2026-08-17-9.53
2026-08-16-4.73
2026-08-15-4.26
2026-08-14-12.19
2026-08-13-5.49
2026-08-12-13.95
2026-08-11-10.76
2026-08-10-8.05
2026-08-09-8.39

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KMSP, lead day 8-20 to -18 °F: 0 days-18 to -16 °F: 1 day-16 to -14 °F: 0 days-14 to -12 °F: 3 days-12 to -10 °F: 2 days-10 to -8 °F: 3 days-8 to -6 °F: 3 days-6 to -4 °F: 8 days-4 to -2 °F: 3 days-2 to 0 °F: 3 days0 to 2 °F: 1 day2 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| 5.41 · P90 |e| 12.5 °F-200+20 °Fn = 28 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
-18.00-16.001
-16.00-14.000
-14.00-12.003
-12.00-10.002
-10.00-8.003
-8.00-6.003
-6.00-4.008
-4.00-2.003
-2.00+0.003
+0.00+2.001
+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
2026-08226.31 -6.05
2026-0166.83 -6.83

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-09 → 2026-08-30 28
GraphCast (IFS init)2026-01-09 → 2026-08-30 28
GraphCast (IFS init)2026-01-09 → 2026-08-30 27
GraphCast (IFS init)2026-01-09 → 2026-08-30 27

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 22 -0.17 [-2.07, 2.03] no
NCEP GFS 22 -0.79 [-2.47, 1.14] no
ECMWF IFS HRES 17 +0.18 [-0.58, 1.44] no
Persistence (baseline) 22 +3.08 [0.26, 6.16] yes

Cite this page

ShortCastCheck, KMSP graphcast_ifs lead 8, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KMSP/model/graphcast_ifs/lead/8/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KMSP (Minneapolis-St Paul), model graphcast_ifs, lead day 8. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KMSP/model/graphcast_ifs/lead/8/

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