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

Washington Reagan · GraphCast (IFS init) · lead day 0

KDCA · 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 QC4.64 [3.88, 5.43]1.46-4.64 [-5.43, -3.88]4.96 [4.21, 5.64]0% [0%, 0%]11%25%——2026-08-01 → 2026-08-30
tmax00Zbilinear90d28 1 QC4.64 [3.81, 5.62]1.46-4.64 [-5.62, -3.81]4.96 [4.17, 5.78]0% [0%, 0%]11%25%——2026-08-01 → 2026-08-30
tmax00Zbilinear365d34 1 QC4.33 [3.48, 5.32]1.50-4.33 [-5.32, -3.48]4.70 [3.84, 5.53]3% [0%, 10%]12%26%——2026-01-01 → 2026-08-30
tmax00Zbilinearall34 1 QC4.33 [3.48, 5.28]1.50-4.33 [-5.28, -3.48]4.70 [3.82, 5.49]3% [0%, 11%]12%26%——2026-01-01 → 2026-08-30
tmax00Znearest30d28 1 QC4.53 [3.74, 5.36]1.56-4.53 [-5.36, -3.74]4.89 [4.14, 5.58]0% [0%, 0%]14%29%——2026-08-01 → 2026-08-30
tmax00Znearest90d28 1 QC4.53 [3.69, 5.56]1.56-4.53 [-5.56, -3.69]4.89 [4.07, 5.76]0% [0%, 0%]14%29%——2026-08-01 → 2026-08-30
tmax00Znearest365d34 1 QC4.18 [3.28, 5.25]1.64-4.18 [-5.24, -3.28]4.60 [3.68, 5.46]3% [0%, 10%]15%29%——2026-01-01 → 2026-08-30
tmax00Znearestall34 1 QC4.18 [3.27, 5.19]1.64-4.18 [-5.19, -3.26]4.60 [3.67, 5.44]3% [0%, 11%]15%29%——2026-01-01 → 2026-08-30
tmin00Zbilinear30d28 1 QC1.44 [1.14, 1.80]1.46+0.38 [-0.33, 1.02]1.97 [1.55, 2.32]50% [32%, 67%]71%89%——2026-08-01 → 2026-08-30
tmin00Zbilinear90d28 1 QC1.44 [1.14, 1.89]1.46+0.38 [-0.67, 1.11]1.97 [1.51, 2.37]50% [26%, 64%]71%89%——2026-08-01 → 2026-08-30
tmin00Zbilinear365d34 1 QC1.42 [1.11, 1.81]1.44+0.07 [-1.07, 0.89]1.92 [1.50, 2.25]47% [25%, 64%]71%91%——2026-01-01 → 2026-08-30
tmin00Zbilinearall34 1 QC1.42 [1.10, 1.83]1.44+0.07 [-0.96, 0.85]1.92 [1.44, 2.27]47% [25%, 62%]71%91%——2026-01-01 → 2026-08-30
tmin00Znearest30d28 1 QC1.62 [1.21, 1.97]1.53+0.91 [0.19, 1.57]2.15 [1.71, 2.52]36% [16%, 55%]71%86%——2026-08-01 → 2026-08-30
tmin00Znearest90d28 1 QC1.62 [1.24, 2.03]1.53+0.91 [-0.18, 1.65]2.15 [1.71, 2.50]36% [11%, 54%]71%86%——2026-08-01 → 2026-08-30
tmin00Znearest365d34 1 QC1.52 [1.15, 1.89]1.48+0.61 [-0.54, 1.45]2.02 [1.48, 2.42]38% [17%, 57%]74%88%——2026-01-01 → 2026-08-30
tmin00Znearestall34 1 QC1.52 [1.13, 1.89]1.48+0.61 [-0.41, 1.39]2.02 [1.47, 2.40]38% [15%, 56%]74%88%——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 KDCA, lead day 0, 00Z bilinear tmax+10+50-5-102026-08-01: -2.9 °F2026-08-02: -2.63 °F2026-08-03: -6.12 °F2026-08-04: -5.31 °F2026-08-05: -6.93 °F2026-08-06: -1.36 °F2026-08-07: -3.03 °F2026-08-08: -4.88 °F2026-08-09: -4.82 °F2026-08-10: -1.45 °F2026-08-11: -4.38 °F2026-08-12: -3.35 °F2026-08-13: -1.8 °F2026-08-14: -2.73 °F2026-08-15: -5.77 °F2026-08-16: -4.37 °F2026-08-17: -6.53 °F2026-08-18: -4.64 °F2026-08-19: -4.41 °F2026-08-20: -7.8 °F2026-08-21: -5.85 °F2026-08-22: -2.87 °F2026-08-23: -6.13 °F2026-08-24: -5.59 °F2026-08-25: -5.66 °F2026-08-28: -7.09 °F2026-08-29: -6.92 °F2026-08-30: -4.67 °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
2026-08-30-4.67
2026-08-29-6.92
2026-08-28-7.09
2026-08-27—
2026-08-26—
2026-08-25-5.66
2026-08-24-5.59
2026-08-23-6.13
2026-08-22-2.87
2026-08-21-5.85
2026-08-20-7.80
2026-08-19-4.41
2026-08-18-4.64
2026-08-17-6.53
2026-08-16-4.37
2026-08-15-5.77
2026-08-14-2.73
2026-08-13-1.80
2026-08-12-3.35
2026-08-11-4.38
2026-08-10-1.45
2026-08-09-4.82
2026-08-08-4.88
2026-08-07-3.03
2026-08-06-1.36
2026-08-05-6.93
2026-08-04-5.31
2026-08-03-6.12
2026-08-02-2.63
2026-08-01-2.90

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KDCA, lead day 0-10 to -9 °F: 0 days-9 to -8 °F: 0 days-8 to -7 °F: 2 days-7 to -6 °F: 5 days-6 to -5 °F: 5 days-5 to -4 °F: 7 days-4 to -3 °F: 6 days-3 to -2 °F: 5 days-2 to -1 °F: 3 days-1 to 0 °F: 1 day0 to 1 °F: 0 days1 to 2 °F: 0 days2 to 3 °F: 0 days3 to 4 °F: 0 days4 to 5 °F: 0 days5 to 6 °F: 0 days6 to 7 °F: 0 days7 to 8 °F: 0 days8 to 9 °F: 0 days9 to 10 °F: 0 daysdashed: P50 |e| 4.39 · P90 |e| 6.8 °F-100+10 °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
-10.00-9.000
-9.00-8.000
-8.00-7.002
-7.00-6.005
-6.00-5.005
-5.00-4.007
-4.00-3.006
-3.00-2.005
-2.00-1.003
-1.00+0.001
+0.00+1.000
+1.00+2.000
+2.00+3.000
+3.00+4.000
+4.00+5.000
+5.00+6.000
+6.00+7.000
+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
2026-08284.64 -4.64
2026-0162.89 -2.89

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 +2.42 [2.11, 2.79] yes
Aurora (GFS init) 2 -0.85 [-2.42, 0.73] no
Aurora (IFS init) 3 -0.38 [-1.67, 0.26] no
FourCastNet v2 (GFS init) 2 +1.66 [0.19, 3.12] yes
FourCastNet v2 (IFS init) 3 +0.52 [-1.25, 1.40] no
NCEP GFS 28 +2.27 [1.01, 3.74] yes
GraphCast (GFS init) 2 -0.14 [-0.46, 0.17] no
ECMWF IFS HRES 22 +1.78 [1.27, 3.06] yes
Pangu-Weather (GFS init) 2 +3.58 [1.62, 5.54] yes
Pangu-Weather (IFS init) 3 +3.43 [1.41, 4.44] yes

Cite this page

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

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KDCA (Washington Reagan), 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/KDCA/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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