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

Washington Reagan · GraphCast (IFS init) · lead day 1

KDCA · graphcast_ifs · lead 1

Target day = initialization date + 1 day. 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
tmax00Zbilinear30d27 1 QC4.97 [4.18, 5.74]1.25-4.97 [-5.74, -4.18]5.19 [4.39, 5.84]0% [0%, 0%]0%11%-0.34+0.662026-08-02 → 2026-08-30
tmax00Zbilinear90d27 1 QC4.97 [4.17, 5.78]1.25-4.97 [-5.78, -4.17]5.19 [4.41, 5.89]0% [0%, 0%]0%11%-0.34+0.662026-08-02 → 2026-08-30
tmax00Zbilinear365d33 1 QC4.62 [3.69, 5.62]1.40-4.62 [-5.62, -3.69]4.91 [4.02, 5.71]3% [0%, 11%]3%21%-0.13+0.652026-01-02 → 2026-08-30
tmax00Zbilinearall33 1 QC4.62 [3.71, 5.55]1.40-4.62 [-5.55, -3.71]4.91 [4.04, 5.70]3% [0%, 10%]3%21%-0.13+0.652026-01-02 → 2026-08-30
tmax00Znearest30d27 1 QC4.86 [4.07, 5.61]1.25-4.86 [-5.61, -4.07]5.07 [4.30, 5.72]0% [0%, 0%]0%11%-0.31+0.662026-08-02 → 2026-08-30
tmax00Znearest90d27 1 QC4.86 [4.07, 5.66]1.25-4.86 [-5.66, -4.07]5.07 [4.30, 5.77]0% [0%, 0%]0%11%-0.31+0.662026-08-02 → 2026-08-30
tmax00Znearest365d33 1 QC4.47 [3.49, 5.52]1.41-4.46 [-5.52, -3.48]4.77 [3.85, 5.61]3% [0%, 11%]3%21%-0.09+0.652026-01-02 → 2026-08-30
tmax00Znearestall33 1 QC4.47 [3.54, 5.42]1.41-4.46 [-5.42, -3.53]4.77 [3.88, 5.57]3% [0%, 10%]3%21%-0.09+0.652026-01-02 → 2026-08-30
tmax12Zbilinear30d27 1 QC4.82 [4.08, 5.60]1.35-4.82 [-5.60, -4.08]5.09 [4.37, 5.73]0% [0%, 0%]11%19%-0.30+0.642026-08-02 → 2026-08-30
tmax12Zbilinear90d27 1 QC4.82 [4.11, 5.70]1.35-4.82 [-5.70, -4.11]5.09 [4.39, 5.85]0% [0%, 0%]11%19%-0.30+0.642026-08-02 → 2026-08-30
tmax12Zbilinear365d32 1 QC4.56 [3.76, 5.49]1.45-4.56 [-5.49, -3.76]4.89 [4.15, 5.67]3% [0%, 12%]16%22%-0.20+0.622026-01-02 → 2026-08-30
tmax12Zbilinearall32 1 QC4.56 [3.77, 5.42]1.45-4.56 [-5.42, -3.77]4.89 [4.15, 5.59]3% [0%, 11%]16%22%-0.20+0.622026-01-02 → 2026-08-30
tmax12Znearest30d27 1 QC4.67 [3.95, 5.42]1.34-4.67 [-5.42, -3.95]4.95 [4.26, 5.58]0% [0%, 0%]7%22%-0.26+0.642026-08-02 → 2026-08-30
tmax12Znearest90d27 1 QC4.67 [3.97, 5.55]1.34-4.67 [-5.55, -3.97]4.95 [4.26, 5.72]0% [0%, 0%]7%22%-0.26+0.642026-08-02 → 2026-08-30
tmax12Znearest365d32 1 QC4.39 [3.59, 5.33]1.46-4.39 [-5.33, -3.59]4.73 [3.99, 5.50]3% [0%, 12%]12%25%-0.15+0.622026-01-02 → 2026-08-30
tmax12Znearestall32 1 QC4.39 [3.60, 5.23]1.46-4.39 [-5.23, -3.60]4.73 [3.98, 5.43]3% [0%, 11%]12%25%-0.15+0.622026-01-02 → 2026-08-30
tmin00Zbilinear30d27 1 QC1.66 [1.23, 2.00]1.68+0.34 [-0.58, 1.18]2.10 [1.61, 2.41]33% [17%, 54%]63%85%+0.28+0.282026-08-02 → 2026-08-30
tmin00Zbilinear90d27 1 QC1.66 [1.20, 2.02]1.68+0.34 [-0.74, 1.25]2.10 [1.53, 2.42]33% [16%, 58%]63%85%+0.28+0.282026-08-02 → 2026-08-30
tmin00Zbilinear365d33 1 QC1.72 [1.30, 2.04]1.74+0.17 [-0.89, 1.16]2.15 [1.65, 2.44]33% [18%, 55%]58%85%+0.26+0.262026-01-02 → 2026-08-30
tmin00Zbilinearall33 1 QC1.72 [1.31, 2.06]1.74+0.17 [-0.85, 1.05]2.15 [1.70, 2.46]33% [18%, 54%]58%85%+0.26+0.262026-01-02 → 2026-08-30
tmin00Znearest30d27 1 QC1.76 [1.18, 2.18]1.64+0.95 [0.03, 1.80]2.26 [1.53, 2.72]37% [23%, 57%]63%85%+0.23+0.292026-08-02 → 2026-08-30
tmin00Znearest90d27 1 QC1.76 [1.09, 2.22]1.64+0.95 [-0.08, 1.85]2.26 [1.39, 2.75]37% [21%, 59%]63%85%+0.23+0.292026-08-02 → 2026-08-30
tmin00Znearest365d33 1 QC1.76 [1.21, 2.15]1.70+0.78 [-0.27, 1.74]2.26 [1.59, 2.70]36% [23%, 56%]64%85%+0.25+0.272026-01-02 → 2026-08-30
tmin00Znearestall33 1 QC1.76 [1.23, 2.20]1.70+0.78 [-0.24, 1.68]2.26 [1.62, 2.73]36% [22%, 55%]64%85%+0.25+0.272026-01-02 → 2026-08-30
tmin12Zbilinear30d27 1 QC1.49 [1.02, 1.95]1.47+0.10 [-0.76, 0.84]1.95 [1.50, 2.33]37% [18%, 59%]70%81%+0.35+0.362026-08-02 → 2026-08-30
tmin12Zbilinear90d27 1 QC1.49 [0.93, 2.07]1.47+0.10 [-0.94, 0.89]1.95 [1.36, 2.44]37% [15%, 61%]70%81%+0.35+0.362026-08-02 → 2026-08-30
tmin12Zbilinear365d32 1 QC1.53 [0.99, 2.07]1.56-0.19 [-1.40, 0.71]1.96 [1.44, 2.42]34% [13%, 57%]69%84%+0.34+0.322026-01-02 → 2026-08-30
tmin12Zbilinearall32 1 QC1.53 [1.01, 2.03]1.56-0.19 [-1.31, 0.71]1.96 [1.44, 2.41]34% [15%, 56%]69%84%+0.34+0.322026-01-02 → 2026-08-30
tmin12Znearest30d27 1 QC1.78 [1.36, 2.15]1.54+0.72 [-0.20, 1.51]2.16 [1.68, 2.50]37% [23%, 54%]67%85%+0.22+0.342026-08-02 → 2026-08-30
tmin12Znearest90d27 1 QC1.78 [1.29, 2.17]1.54+0.72 [-0.36, 1.56]2.16 [1.59, 2.55]37% [23%, 56%]67%85%+0.22+0.342026-08-02 → 2026-08-30
tmin12Znearest365d32 1 QC1.73 [1.30, 2.09]1.62+0.43 [-0.80, 1.37]2.08 [1.54, 2.45]38% [25%, 55%]66%88%+0.25+0.302026-01-02 → 2026-08-30
tmin12Znearestall32 1 QC1.73 [1.30, 2.11]1.62+0.43 [-0.74, 1.37]2.08 [1.54, 2.46]38% [25%, 54%]66%88%+0.25+0.302026-01-02 → 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 1, 00Z bilinear tmax+10+50-5-102026-08-02: -5.1 °F2026-08-03: -5.75 °F2026-08-04: -6.56 °F2026-08-05: -7.02 °F2026-08-06: -2.57 °F2026-08-07: -3.01 °F2026-08-08: -4.38 °F2026-08-09: -4.69 °F2026-08-10: -2.99 °F2026-08-11: -2.81 °F2026-08-12: -3.04 °F2026-08-13: -3.25 °F2026-08-14: -4.03 °F2026-08-15: -6.53 °F2026-08-16: -4.1 °F2026-08-17: -6 °F2026-08-18: -4.62 °F2026-08-19: -4.91 °F2026-08-20: -7.54 °F2026-08-21: -7.14 °F2026-08-22: -3.37 °F2026-08-23: -5.94 °F2026-08-24: -6.05 °F2026-08-25: -6.76 °F2026-08-26: -4.94 °F2026-08-29: -5.78 °F2026-08-30: -5.4 °F2026-08-022026-08-30°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 (29 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-5.40
2026-08-29-5.78
2026-08-28—
2026-08-27—
2026-08-26-4.94
2026-08-25-6.76
2026-08-24-6.05
2026-08-23-5.94
2026-08-22-3.37
2026-08-21-7.14
2026-08-20-7.54
2026-08-19-4.91
2026-08-18-4.62
2026-08-17-6.00
2026-08-16-4.10
2026-08-15-6.53
2026-08-14-4.03
2026-08-13-3.25
2026-08-12-3.04
2026-08-11-2.81
2026-08-10-2.99
2026-08-09-4.69
2026-08-08-4.38
2026-08-07-3.01
2026-08-06-2.57
2026-08-05-7.02
2026-08-04-6.56
2026-08-03-5.75
2026-08-02-5.10

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KDCA, lead day 1-10 to -9 °F: 0 days-9 to -8 °F: 0 days-8 to -7 °F: 3 days-7 to -6 °F: 4 days-6 to -5 °F: 7 days-5 to -4 °F: 8 days-4 to -3 °F: 4 days-3 to -2 °F: 6 days-2 to -1 °F: 0 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| 4.87 · P90 |e| 6.72 °F-100+10 °Fn = 33 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
-8.00-7.003
-7.00-6.004
-6.00-5.007
-5.00-4.008
-4.00-3.004
-3.00-2.006
-2.00-1.000
-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
2026-08274.97 -4.97
2026-0163.00 -3.00

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-02 → 2026-08-30 33
GraphCast (IFS init)2026-01-02 → 2026-08-30 33
GraphCast (IFS init)2026-01-02 → 2026-08-30 32
GraphCast (IFS init)2026-01-02 → 2026-08-30 32

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 27 +2.68 [2.10, 3.21] yes
Aurora (GFS init) 1 -2.68 [-2.68, -2.68] yes
Aurora (IFS init) 2 -0.49 [-1.26, 0.28] no
FourCastNet v2 (GFS init) 1 +1.77 [1.77, 1.77] yes
FourCastNet v2 (IFS init) 2 +3.15 [2.40, 3.89] yes
NCEP GFS 27 +1.11 [0.22, 2.39] yes
GraphCast (GFS init) 1 +0.27 [0.27, 0.27] yes
ECMWF IFS HRES 21 +1.61 [0.72, 2.68] yes
Pangu-Weather (GFS init) 1 +2.88 [2.88, 2.88] yes
Pangu-Weather (IFS init) 2 +3.63 [2.42, 4.84] yes
Persistence (baseline) 27 +1.27 [-0.21, 2.67] no

Cite this page

ShortCastCheck, KDCA graphcast_ifs lead 1, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KDCA/model/graphcast_ifs/lead/1/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KDCA (Washington Reagan), model graphcast_ifs, lead day 1. 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/1/

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

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