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

Washington Reagan · GraphCast (IFS init) · lead day 7

KDCA · 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 QC4.82 [3.69, 6.08]3.06-4.27 [-5.90, -3.14]5.64 [4.46, 6.73]9% [0%, 15%]17%30%-0.07+0.332026-08-08 → 2026-08-30
tmax00Zbilinear90d23 1 QC4.82 [3.51, 6.52]3.06-4.27 [-6.49, -3.10]5.64 [4.26, 7.01]9% [0%, 14%]17%30%-0.07+0.332026-08-08 → 2026-08-30
tmax00Zbilinear365d29 1 QC5.13 [3.92, 6.58]3.90-3.35 [-5.44, -1.15]5.99 [4.76, 7.18]7% [0%, 13%]21%31%+0.10+0.302026-01-08 → 2026-08-30
tmax00Zbilinearall29 1 QC5.13 [3.89, 6.60]3.90-3.35 [-5.34, -0.91]5.99 [4.72, 7.19]7% [0%, 13%]21%31%+0.10+0.302026-01-08 → 2026-08-30
tmax00Znearest30d23 1 QC4.78 [3.62, 6.07]3.06-4.18 [-5.86, -3.02]5.59 [4.38, 6.70]13% [0%, 23%]17%30%-0.06+0.332026-08-08 → 2026-08-30
tmax00Znearest90d23 1 QC4.78 [3.44, 6.51]3.06-4.18 [-6.46, -2.98]5.59 [4.16, 6.96]13% [0%, 24%]17%30%-0.06+0.332026-08-08 → 2026-08-30
tmax00Znearest365d29 1 QC5.12 [3.85, 6.61]3.94-3.21 [-5.34, -0.92]5.97 [4.69, 7.19]10% [0%, 20%]17%31%+0.11+0.292026-01-08 → 2026-08-30
tmax00Znearestall29 1 QC5.12 [3.83, 6.65]3.94-3.21 [-5.28, -0.69]5.97 [4.67, 7.23]10% [0%, 20%]17%31%+0.11+0.292026-01-08 → 2026-08-30
tmax12Zbilinear30d23 1 QC5.24 [3.64, 7.07]2.68-4.87 [-6.87, -3.43]5.97 [4.37, 7.52]4% [0%, 12%]17%22%-0.16+0.412026-08-08 → 2026-08-30
tmax12Zbilinear90d23 1 QC5.24 [3.43, 7.47]2.68-4.87 [-7.36, -3.43]5.97 [4.21, 7.75]4% [0%, 12%]17%22%-0.16+0.412026-08-08 → 2026-08-30
tmax12Zbilinear365d28 1 QC5.27 [3.69, 6.95]3.70-3.52 [-6.15, -0.25]5.97 [4.42, 7.49]4% [0%, 10%]18%21%+0.10+0.352026-01-08 → 2026-08-30
tmax12Zbilinearall28 1 QC5.27 [3.76, 7.02]3.70-3.52 [-6.21, -0.04]5.97 [4.46, 7.50]4% [0%, 10%]18%21%+0.10+0.352026-01-08 → 2026-08-30
tmax12Znearest30d23 1 QC5.14 [3.54, 6.95]2.69-4.75 [-6.74, -3.33]5.88 [4.31, 7.43]9% [0%, 21%]17%26%-0.14+0.412026-08-08 → 2026-08-30
tmax12Znearest90d23 1 QC5.14 [3.34, 7.36]2.69-4.75 [-7.25, -3.32]5.88 [4.14, 7.63]9% [0%, 21%]17%26%-0.14+0.412026-08-08 → 2026-08-30
tmax12Znearest365d28 1 QC5.19 [3.61, 6.89]3.72-3.40 [-6.05, -0.10]5.90 [4.34, 7.41]7% [0%, 19%]18%25%+0.11+0.352026-01-08 → 2026-08-30
tmax12Znearestall28 1 QC5.19 [3.68, 6.90]3.72-3.40 [-6.07, 0.10]5.90 [4.44, 7.39]7% [0%, 19%]18%25%+0.11+0.352026-01-08 → 2026-08-30
tmin00Zbilinear30d23 1 QC3.25 [2.46, 3.79]3.21+0.20 [-1.82, 2.35]4.05 [3.00, 4.78]22% [10%, 32%]39%48%+0.31+0.322026-08-08 → 2026-08-30
tmin00Zbilinear90d23 1 QC3.25 [2.35, 3.82]3.21+0.20 [-2.02, 2.53]4.05 [2.89, 4.77]22% [6%, 32%]39%48%+0.31+0.322026-08-08 → 2026-08-30
tmin00Zbilinear365d29 1 QC3.55 [2.59, 4.40]3.36+1.04 [-1.39, 3.65]4.48 [3.22, 5.57]17% [0%, 29%]38%48%+0.34+0.372026-01-08 → 2026-08-30
tmin00Zbilinearall29 1 QC3.55 [2.68, 4.38]3.36+1.04 [-1.24, 3.56]4.48 [3.26, 5.53]17% [0%, 29%]38%48%+0.34+0.372026-01-08 → 2026-08-30
tmin00Znearest30d23 1 QC3.37 [2.62, 3.99]3.15+0.81 [-1.17, 2.93]4.10 [3.03, 5.01]9% [0%, 19%]30%52%+0.29+0.332026-08-08 → 2026-08-30
tmin00Znearest90d23 1 QC3.37 [2.51, 4.02]3.15+0.81 [-1.40, 3.12]4.10 [2.93, 5.03]9% [0%, 20%]30%52%+0.29+0.332026-08-08 → 2026-08-30
tmin00Znearest365d29 1 QC3.70 [2.74, 4.69]3.33+1.64 [-0.75, 4.23]4.61 [3.18, 5.87]10% [0%, 21%]31%52%+0.31+0.382026-01-08 → 2026-08-30
tmin00Znearestall29 1 QC3.70 [2.79, 4.68]3.33+1.64 [-0.65, 4.14]4.61 [3.25, 5.78]10% [0%, 20%]31%52%+0.31+0.382026-01-08 → 2026-08-30
tmin12Zbilinear30d23 1 QC2.59 [1.98, 3.06]2.56+0.42 [-1.24, 2.19]3.11 [2.50, 3.51]13% [0%, 27%]52%61%+0.45+0.462026-08-08 → 2026-08-30
tmin12Zbilinear90d23 1 QC2.59 [1.81, 3.08]2.56+0.42 [-1.35, 2.30]3.11 [2.30, 3.51]13% [0%, 29%]52%61%+0.45+0.462026-08-08 → 2026-08-30
tmin12Zbilinear365d28 1 QC3.11 [2.15, 4.43]3.03+1.16 [-0.92, 3.60]3.96 [2.64, 5.60]14% [0%, 29%]46%57%+0.43+0.442026-01-08 → 2026-08-30
tmin12Zbilinearall28 1 QC3.11 [2.18, 4.63]3.03+1.16 [-0.91, 3.61]3.96 [2.70, 5.69]14% [0%, 27%]46%57%+0.43+0.442026-01-08 → 2026-08-30
tmin12Znearest30d23 1 QC2.66 [1.86, 3.33]2.55+1.02 [-0.62, 2.78]3.21 [2.36, 3.80]26% [11%, 50%]43%61%+0.44+0.462026-08-08 → 2026-08-30
tmin12Znearest90d23 1 QC2.66 [1.72, 3.39]2.55+1.02 [-0.77, 2.91]3.21 [2.13, 3.84]26% [10%, 54%]43%61%+0.44+0.462026-08-08 → 2026-08-30
tmin12Znearest365d28 1 QC3.22 [2.03, 4.69]3.02+1.75 [-0.33, 4.18]4.15 [2.54, 5.91]21% [6%, 44%]43%57%+0.41+0.442026-01-08 → 2026-08-30
tmin12Znearestall28 1 QC3.22 [2.07, 4.89]3.02+1.75 [-0.32, 4.16]4.15 [2.60, 6.04]21% [0%, 42%]43%57%+0.41+0.442026-01-08 → 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 KDCA, lead day 7, 00Z bilinear tmax+20+100-10-202026-08-08: -4.74 °F2026-08-09: -6.33 °F2026-08-10: -2.39 °F2026-08-11: -1.14 °F2026-08-12: -2.02 °F2026-08-13: -2.19 °F2026-08-14: -0.57 °F2026-08-15: -10.26 °F2026-08-16: +4.13 °F2026-08-17: -10.26 °F2026-08-18: -6.71 °F2026-08-19: -5.99 °F2026-08-20: -3.09 °F2026-08-21: +1.55 °F2026-08-22: +0.64 °F2026-08-23: -3.47 °F2026-08-24: -7.15 °F2026-08-25: -5.77 °F2026-08-26: -5.31 °F2026-08-27: -3.29 °F2026-08-28: -8.84 °F2026-08-29: -5.81 °F2026-08-30: -9.22 °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
2026-08-30-9.22
2026-08-29-5.81
2026-08-28-8.84
2026-08-27-3.29
2026-08-26-5.31
2026-08-25-5.77
2026-08-24-7.15
2026-08-23-3.47
2026-08-22+0.64
2026-08-21+1.55
2026-08-20-3.09
2026-08-19-5.99
2026-08-18-6.71
2026-08-17-10.26
2026-08-16+4.13
2026-08-15-10.26
2026-08-14-0.57
2026-08-13-2.19
2026-08-12-2.02
2026-08-11-1.14
2026-08-10-2.39
2026-08-09-6.33
2026-08-08-4.74

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KDCA, lead day 7-20 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: 2 days-10 to -8 °F: 3 days-8 to -6 °F: 4 days-6 to -4 °F: 5 days-4 to -2 °F: 6 days-2 to 0 °F: 3 days0 to 2 °F: 3 days2 to 4 °F: 0 days4 to 6 °F: 1 day6 to 8 °F: 0 days8 to 10 °F: 2 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| 5.31 · P90 |e| 9.3 °F-200+20 °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
-20.00-18.000
-18.00-16.000
-16.00-14.000
-14.00-12.000
-12.00-10.002
-10.00-8.003
-8.00-6.004
-6.00-4.005
-4.00-2.006
-2.00+0.003
+0.00+2.003
+2.00+4.000
+4.00+6.001
+6.00+8.000
+8.00+10.002
+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
2026-08234.82 -4.27
2026-0166.33 +0.20

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 +1.56 [0.47, 2.89] yes
NCEP GFS 23 +0.35 [-0.96, 2.48] no
ECMWF IFS HRES 18 +1.52 [0.14, 4.27] yes
Persistence (baseline) 23 +0.30 [-1.12, 2.04] no

Cite this page

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

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