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

Minneapolis-St Paul · GraphCast (IFS init) · lead day 4

KMSP · graphcast_ifs · lead 4

Target day = initialization date + 4 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.

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
tmax00Zbilinear30d256.04 [5.13, 6.75]2.75-5.92 [-6.68, -4.85]6.76 [5.89, 7.35]4% [0%, 11%]12%28%-0.47+0.332026-08-05 → 2026-08-29
tmax00Zbilinear90d256.04 [5.10, 6.76]2.75-5.92 [-6.69, -4.84]6.76 [5.82, 7.38]4% [0%, 12%]12%28%-0.47+0.332026-08-05 → 2026-08-29
tmax00Zbilinear365d315.58 [4.36, 6.41]2.76-5.48 [-6.36, -4.23]6.35 [5.10, 7.04]3% [0%, 10%]16%32%-0.01+0.512026-01-05 → 2026-08-29
tmax00Zbilinearall315.58 [4.26, 6.44]2.76-5.48 [-6.38, -4.09]6.35 [4.91, 7.11]3% [0%, 10%]16%32%-0.01+0.512026-01-05 → 2026-08-29
tmax00Znearest30d256.06 [5.14, 6.78]2.74-5.94 [-6.72, -4.85]6.78 [5.88, 7.39]4% [0%, 11%]12%24%-0.47+0.332026-08-05 → 2026-08-29
tmax00Znearest90d256.06 [5.09, 6.81]2.74-5.94 [-6.73, -4.83]6.78 [5.80, 7.41]4% [0%, 12%]12%24%-0.47+0.332026-08-05 → 2026-08-29
tmax00Znearest365d315.60 [4.38, 6.43]2.76-5.50 [-6.39, -4.26]6.38 [5.16, 7.07]6% [0%, 15%]19%29%-0.01+0.512026-01-05 → 2026-08-29
tmax00Znearestall315.60 [4.27, 6.46]2.76-5.50 [-6.41, -4.11]6.38 [4.96, 7.14]6% [0%, 14%]19%29%-0.01+0.512026-01-05 → 2026-08-29
tmax12Zbilinear30d256.53 [5.67, 7.10]2.42-6.35 [-7.07, -5.12]7.03 [6.21, 7.52]0% [0%, 0%]8%12%-0.58+0.412026-08-05 → 2026-08-29
tmax12Zbilinear90d256.53 [5.60, 7.09]2.42-6.35 [-7.08, -4.99]7.03 [6.12, 7.52]0% [0%, 0%]8%12%-0.58+0.412026-08-05 → 2026-08-29
tmax12Zbilinear365d306.07 [4.68, 6.85]2.42-5.92 [-6.83, -4.52]6.65 [5.30, 7.30]0% [0%, 0%]13%17%-0.07+0.572026-01-05 → 2026-08-29
tmax12Zbilinearall306.07 [4.46, 6.91]2.42-5.92 [-6.84, -4.22]6.65 [5.13, 7.35]0% [0%, 0%]13%17%-0.07+0.572026-01-05 → 2026-08-29
tmax12Znearest30d256.56 [5.67, 7.14]2.43-6.37 [-7.11, -5.11]7.06 [6.23, 7.55]0% [0%, 0%]8%12%-0.59+0.412026-08-05 → 2026-08-29
tmax12Znearest90d256.56 [5.60, 7.13]2.43-6.37 [-7.12, -4.95]7.06 [6.11, 7.56]0% [0%, 0%]8%12%-0.59+0.412026-08-05 → 2026-08-29
tmax12Znearest365d306.09 [4.66, 6.89]2.45-5.94 [-6.88, -4.53]6.68 [5.35, 7.34]0% [0%, 0%]13%17%-0.08+0.572026-01-05 → 2026-08-29
tmax12Znearestall306.09 [4.44, 6.94]2.45-5.94 [-6.88, -4.20]6.68 [5.16, 7.38]0% [0%, 0%]13%17%-0.08+0.572026-01-05 → 2026-08-29
tmin00Zbilinear30d252.22 [1.38, 3.14]1.81-1.61 [-2.75, -0.42]2.70 [1.70, 3.54]24% [9%, 40%]48%76%+0.48+0.572026-08-05 → 2026-08-29
tmin00Zbilinear90d252.22 [1.37, 3.19]1.81-1.61 [-2.77, -0.39]2.70 [1.68, 3.58]24% [7%, 42%]48%76%+0.48+0.572026-08-05 → 2026-08-29
tmin00Zbilinear365d312.25 [1.47, 3.19]1.99-1.33 [-2.57, -0.12]2.72 [1.80, 3.58]26% [10%, 41%]45%74%+0.61+0.672026-01-05 → 2026-08-29
tmin00Zbilinearall312.25 [1.49, 3.12]1.99-1.33 [-2.55, -0.16]2.72 [1.83, 3.51]26% [11%, 43%]45%74%+0.61+0.672026-01-05 → 2026-08-29
tmin00Znearest30d252.29 [1.41, 3.25]1.86-1.73 [-2.91, -0.50]2.81 [1.73, 3.70]24% [9%, 40%]48%68%+0.46+0.562026-08-05 → 2026-08-29
tmin00Znearest90d252.29 [1.41, 3.33]1.86-1.73 [-2.93, -0.47]2.81 [1.72, 3.76]24% [7%, 42%]48%68%+0.46+0.562026-08-05 → 2026-08-29
tmin00Znearest365d312.32 [1.49, 3.31]2.02-1.46 [-2.72, -0.23]2.82 [1.84, 3.75]26% [10%, 41%]45%65%+0.60+0.662026-01-05 → 2026-08-29
tmin00Znearestall312.32 [1.51, 3.24]2.02-1.46 [-2.69, -0.30]2.82 [1.87, 3.65]26% [11%, 43%]45%65%+0.60+0.662026-01-05 → 2026-08-29
tmin12Zbilinear30d252.14 [1.37, 2.97]1.87-1.53 [-2.56, -0.51]2.66 [1.74, 3.47]32% [17%, 47%]52%68%+0.50+0.562026-08-05 → 2026-08-29
tmin12Zbilinear90d252.14 [1.34, 3.08]1.87-1.53 [-2.58, -0.45]2.66 [1.69, 3.56]32% [14%, 48%]52%68%+0.50+0.562026-08-05 → 2026-08-29
tmin12Zbilinear365d302.06 [1.33, 2.99]1.79-1.50 [-2.58, -0.59]2.59 [1.70, 3.47]37% [21%, 53%]57%70%+0.64+0.702026-01-05 → 2026-08-29
tmin12Zbilinearall302.06 [1.33, 2.93]1.79-1.50 [-2.56, -0.61]2.59 [1.70, 3.37]37% [20%, 53%]57%70%+0.64+0.702026-01-05 → 2026-08-29
tmin12Znearest30d252.19 [1.36, 3.11]1.91-1.66 [-2.72, -0.61]2.76 [1.76, 3.62]28% [7%, 46%]52%68%+0.49+0.552026-08-05 → 2026-08-29
tmin12Znearest90d252.19 [1.35, 3.19]1.91-1.66 [-2.75, -0.58]2.76 [1.74, 3.70]28% [0%, 48%]52%68%+0.49+0.552026-08-05 → 2026-08-29
tmin12Znearest365d302.11 [1.35, 3.11]1.81-1.62 [-2.76, -0.71]2.68 [1.72, 3.62]30% [11%, 49%]57%70%+0.63+0.692026-01-05 → 2026-08-29
tmin12Znearestall302.11 [1.34, 3.02]1.81-1.62 [-2.72, -0.73]2.68 [1.73, 3.53]30% [10%, 47%]57%70%+0.63+0.692026-01-05 → 2026-08-29

+ 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 4, 00Z bilinear tmax+20+100-10-202026-08-05: -5.92 °F2026-08-06: -2.59 °F2026-08-07: +1.5 °F2026-08-08: -6.08 °F2026-08-09: -10.23 °F2026-08-10: -8.83 °F2026-08-11: -9.6 °F2026-08-12: -7.79 °F2026-08-13: -0.19 °F2026-08-14: -6.2 °F2026-08-15: -2.89 °F2026-08-16: -8.18 °F2026-08-17: -8.93 °F2026-08-18: -4.58 °F2026-08-19: -9.85 °F2026-08-20: -1.92 °F2026-08-21: -2.78 °F2026-08-22: -5.06 °F2026-08-23: -7.98 °F2026-08-24: -9.27 °F2026-08-25: -2.16 °F2026-08-26: -4.92 °F2026-08-27: -9.94 °F2026-08-28: -8.5 °F2026-08-29: -5.22 °F2026-08-052026-08-29°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 (25 days, newest first) · download CSV
Climatological dayError °F
2026-08-29-5.22
2026-08-28-8.50
2026-08-27-9.94
2026-08-26-4.92
2026-08-25-2.16
2026-08-24-9.27
2026-08-23-7.98
2026-08-22-5.06
2026-08-21-2.78
2026-08-20-1.92
2026-08-19-9.85
2026-08-18-4.58
2026-08-17-8.93
2026-08-16-8.18
2026-08-15-2.89
2026-08-14-6.20
2026-08-13-0.19
2026-08-12-7.79
2026-08-11-9.60
2026-08-10-8.83
2026-08-09-10.23
2026-08-08-6.08
2026-08-07+1.50
2026-08-06-2.59
2026-08-05-5.92

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KMSP, lead day 4-20 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: 1 day-10 to -8 °F: 8 days-8 to -6 °F: 6 days-6 to -4 °F: 5 days-4 to -2 °F: 6 days-2 to 0 °F: 4 days0 to 2 °F: 1 day2 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| 5.92 · P90 |e| 9.6 °F-200+20 °Fn = 31 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
-12.00-10.001
-10.00-8.008
-8.00-6.006
-6.00-4.005
-4.00-2.006
-2.00+0.004
+0.00+2.001
+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
2026-08256.04 -5.92
2026-0163.63 -3.63

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-05 → 2026-08-29 31
GraphCast (IFS init)2026-01-05 → 2026-08-29 31
GraphCast (IFS init)2026-01-05 → 2026-08-29 30
GraphCast (IFS init)2026-01-05 → 2026-08-29 30

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 25 +1.94 [1.29, 2.54] yes
NCEP GFS 25 +2.44 [0.59, 4.21] yes
ECMWF IFS HRES 19 +3.12 [2.33, 3.98] yes
Persistence (baseline) 25 +1.92 [-0.03, 3.88] no

Cite this page

ShortCastCheck, KMSP graphcast_ifs lead 4, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KMSP/model/graphcast_ifs/lead/4/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KMSP (Minneapolis-St Paul), model graphcast_ifs, lead day 4. 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/4/

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

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