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

Washington Reagan · GraphCast (IFS init) · lead day 2

KDCA · graphcast_ifs · lead 2

Target day = initialization date + 2 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
tmax00Zbilinear30d26 1 QC4.78 [3.69, 5.80]1.82-4.78 [-5.80, -3.69]5.23 [4.18, 6.09]8% [0%, 17%]8%23%-0.41+0.462026-08-03 → 2026-08-30
tmax00Zbilinear90d26 1 QC4.78 [3.68, 5.86]1.82-4.78 [-5.86, -3.68]5.23 [4.19, 6.12]8% [0%, 17%]8%23%-0.41+0.462026-08-03 → 2026-08-30
tmax00Zbilinear365d32 1 QC4.53 [3.49, 5.61]1.79-4.53 [-5.61, -3.49]4.98 [3.90, 5.89]6% [0%, 14%]6%28%-0.09+0.562026-01-03 → 2026-08-30
tmax00Zbilinearall32 1 QC4.53 [3.53, 5.58]1.79-4.53 [-5.58, -3.53]4.98 [3.93, 5.87]6% [0%, 14%]6%28%-0.09+0.562026-01-03 → 2026-08-30
tmax00Znearest30d26 1 QC4.64 [3.53, 5.72]1.87-4.64 [-5.72, -3.53]5.13 [4.06, 6.00]8% [0%, 17%]12%27%-0.37+0.452026-08-03 → 2026-08-30
tmax00Znearest90d26 1 QC4.64 [3.54, 5.74]1.87-4.64 [-5.74, -3.54]5.13 [4.06, 6.05]8% [0%, 17%]12%27%-0.37+0.452026-08-03 → 2026-08-30
tmax00Znearest365d32 1 QC4.37 [3.29, 5.48]1.81-4.37 [-5.48, -3.29]4.86 [3.74, 5.80]6% [0%, 14%]16%34%-0.05+0.552026-01-03 → 2026-08-30
tmax00Znearestall32 1 QC4.37 [3.32, 5.47]1.81-4.37 [-5.47, -3.32]4.86 [3.77, 5.76]6% [0%, 14%]16%34%-0.05+0.552026-01-03 → 2026-08-30
tmax12Zbilinear30d26 1 QC4.78 [3.68, 5.88]1.76-4.78 [-5.88, -3.68]5.22 [4.19, 6.11]4% [0%, 11%]19%23%-0.41+0.482026-08-03 → 2026-08-30
tmax12Zbilinear90d26 1 QC4.78 [3.61, 5.93]1.76-4.78 [-5.93, -3.61]5.22 [4.14, 6.17]4% [0%, 11%]19%23%-0.41+0.482026-08-03 → 2026-08-30
tmax12Zbilinear365d31 1 QC4.62 [3.50, 5.74]1.80-4.62 [-5.74, -3.50]5.08 [4.02, 5.97]3% [0%, 10%]23%26%-0.12+0.552026-01-03 → 2026-08-30
tmax12Zbilinearall31 1 QC4.62 [3.59, 5.72]1.80-4.62 [-5.72, -3.59]5.08 [4.10, 5.96]3% [0%, 10%]23%26%-0.12+0.552026-01-03 → 2026-08-30
tmax12Znearest30d26 1 QC4.64 [3.54, 5.75]1.79-4.64 [-5.75, -3.54]5.10 [4.08, 5.98]8% [0%, 20%]15%23%-0.37+0.472026-08-03 → 2026-08-30
tmax12Znearest90d26 1 QC4.64 [3.48, 5.80]1.79-4.64 [-5.80, -3.48]5.10 [4.05, 6.05]8% [0%, 20%]15%23%-0.37+0.472026-08-03 → 2026-08-30
tmax12Znearest365d31 1 QC4.46 [3.33, 5.60]1.82-4.46 [-5.60, -3.33]4.94 [3.90, 5.84]6% [0%, 18%]19%26%-0.08+0.552026-01-03 → 2026-08-30
tmax12Znearestall31 1 QC4.46 [3.41, 5.57]1.82-4.46 [-5.57, -3.41]4.94 [3.95, 5.81]6% [0%, 18%]19%26%-0.08+0.552026-01-03 → 2026-08-30
tmin00Zbilinear30d26 1 QC2.13 [1.73, 2.59]2.14+0.19 [-0.99, 1.18]2.56 [2.09, 3.01]27% [14%, 38%]54%73%+0.33+0.332026-08-03 → 2026-08-30
tmin00Zbilinear90d26 1 QC2.13 [1.73, 2.62]2.14+0.19 [-1.24, 1.25]2.56 [2.06, 3.02]27% [13%, 38%]54%73%+0.33+0.332026-08-03 → 2026-08-30
tmin00Zbilinear365d32 1 QC2.16 [1.73, 2.61]2.18+0.25 [-0.98, 1.31]2.60 [2.02, 3.04]22% [6%, 36%]53%75%+0.29+0.292026-01-03 → 2026-08-30
tmin00Zbilinearall32 1 QC2.16 [1.75, 2.65]2.18+0.25 [-0.99, 1.24]2.60 [2.09, 3.08]22% [8%, 35%]53%75%+0.29+0.292026-01-03 → 2026-08-30
tmin00Znearest30d26 1 QC2.15 [1.63, 2.61]2.14+0.76 [-0.39, 1.73]2.64 [1.98, 3.12]27% [17%, 38%]54%69%+0.33+0.332026-08-03 → 2026-08-30
tmin00Znearest90d26 1 QC2.15 [1.56, 2.65]2.14+0.76 [-0.67, 1.81]2.64 [1.92, 3.18]27% [14%, 40%]54%69%+0.33+0.332026-08-03 → 2026-08-30
tmin00Znearest365d32 1 QC2.12 [1.54, 2.62]2.16+0.81 [-0.37, 1.85]2.66 [1.94, 3.16]31% [19%, 46%]56%69%+0.30+0.292026-01-03 → 2026-08-30
tmin00Znearestall32 1 QC2.12 [1.58, 2.64]2.16+0.81 [-0.42, 1.78]2.66 [2.00, 3.21]31% [18%, 46%]56%69%+0.30+0.292026-01-03 → 2026-08-30
tmin12Zbilinear30d26 1 QC1.91 [1.55, 2.28]1.89+0.18 [-0.97, 1.19]2.38 [1.89, 2.77]42% [26%, 58%]58%77%+0.40+0.412026-08-03 → 2026-08-30
tmin12Zbilinear90d26 1 QC1.91 [1.54, 2.29]1.89+0.18 [-1.10, 1.27]2.38 [1.86, 2.76]42% [21%, 60%]58%77%+0.40+0.412026-08-03 → 2026-08-30
tmin12Zbilinear365d31 1 QC1.90 [1.55, 2.27]1.90+0.10 [-1.06, 1.17]2.35 [1.84, 2.70]39% [19%, 55%]61%77%+0.39+0.402026-01-03 → 2026-08-30
tmin12Zbilinearall31 1 QC1.90 [1.55, 2.29]1.90+0.10 [-1.04, 1.13]2.35 [1.88, 2.74]39% [20%, 55%]61%77%+0.39+0.402026-01-03 → 2026-08-30
tmin12Znearest30d26 1 QC2.01 [1.46, 2.40]1.91+0.76 [-0.39, 1.78]2.51 [1.84, 2.89]31% [19%, 45%]62%77%+0.37+0.402026-08-03 → 2026-08-30
tmin12Znearest90d26 1 QC2.01 [1.37, 2.42]1.91+0.76 [-0.54, 1.86]2.51 [1.68, 2.92]31% [17%, 45%]62%77%+0.37+0.402026-08-03 → 2026-08-30
tmin12Znearest365d31 1 QC1.91 [1.31, 2.33]1.89+0.68 [-0.49, 1.72]2.43 [1.68, 2.83]35% [20%, 53%]65%77%+0.39+0.402026-01-03 → 2026-08-30
tmin12Znearestall31 1 QC1.91 [1.30, 2.36]1.89+0.68 [-0.47, 1.68]2.43 [1.75, 2.88]35% [19%, 53%]65%77%+0.39+0.402026-01-03 → 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 2, 00Z bilinear tmax+10+50-5-102026-08-03: -4.97 °F2026-08-04: -7.91 °F2026-08-05: -8.01 °F2026-08-06: -3.16 °F2026-08-07: -4.31 °F2026-08-08: -3.81 °F2026-08-09: -4.6 °F2026-08-10: -2.78 °F2026-08-11: -0.76 °F2026-08-12: -3.04 °F2026-08-13: -2.33 °F2026-08-14: -2.38 °F2026-08-15: -6.95 °F2026-08-16: -0.98 °F2026-08-17: -6.27 °F2026-08-18: -4.39 °F2026-08-19: -5.71 °F2026-08-20: -8.63 °F2026-08-21: -6.52 °F2026-08-22: -2.52 °F2026-08-23: -5.75 °F2026-08-24: -7.04 °F2026-08-25: -6.58 °F2026-08-26: -5.65 °F2026-08-27: -3.41 °F2026-08-30: -5.76 °F2026-08-032026-08-30°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 (28 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-5.76
2026-08-29—
2026-08-28—
2026-08-27-3.41
2026-08-26-5.65
2026-08-25-6.58
2026-08-24-7.04
2026-08-23-5.75
2026-08-22-2.52
2026-08-21-6.52
2026-08-20-8.63
2026-08-19-5.71
2026-08-18-4.39
2026-08-17-6.27
2026-08-16-0.98
2026-08-15-6.95
2026-08-14-2.38
2026-08-13-2.33
2026-08-12-3.04
2026-08-11-0.76
2026-08-10-2.78
2026-08-09-4.60
2026-08-08-3.81
2026-08-07-4.31
2026-08-06-3.16
2026-08-05-8.01
2026-08-04-7.91
2026-08-03-4.97

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KDCA, lead day 2-10 to -9 °F: 0 days-9 to -8 °F: 2 days-8 to -7 °F: 2 days-7 to -6 °F: 4 days-6 to -5 °F: 6 days-5 to -4 °F: 4 days-4 to -3 °F: 5 days-3 to -2 °F: 7 days-2 to -1 °F: 0 days-1 to 0 °F: 2 days0 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| 4.49 · P90 |e| 7.03 °F-100+10 °Fn = 32 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
-9.00-8.002
-8.00-7.002
-7.00-6.004
-6.00-5.006
-5.00-4.004
-4.00-3.005
-3.00-2.007
-2.00-1.000
-1.00+0.002
+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
2026-08264.78 -4.78
2026-0163.48 -3.48

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-03 → 2026-08-30 32
GraphCast (IFS init)2026-01-03 → 2026-08-30 32
GraphCast (IFS init)2026-01-03 → 2026-08-30 31
GraphCast (IFS init)2026-01-03 → 2026-08-30 31

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 26 +2.20 [1.72, 2.81] yes
Aurora (IFS init) 1 -2.00 [-2.00, -2.00] yes
FourCastNet v2 (IFS init) 1 +2.87 [2.87, 2.87] yes
NCEP GFS 26 +1.75 [0.89, 2.88] yes
ECMWF IFS HRES 20 +0.53 [-1.04, 2.12] no
Pangu-Weather (IFS init) 1 +2.06 [2.06, 2.06] yes
Persistence (baseline) 26 +1.39 [0.10, 3.70] yes

Cite this page

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

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

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