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

Washington Reagan · NCEP GFS · lead day 0

KDCA · gfs · 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, gfs-0p25, starting 2026-08-01 — 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
tmax00Zbilinear30d30 1 QC2.33 [1.58, 3.17]2.14-1.23 [-2.11, -0.32]3.04 [2.09, 3.85]27% [13%, 40%]57%77%——2026-08-01 → 2026-08-30
tmax00Zbilinear90d30 1 QC2.33 [1.32, 3.35]2.14-1.23 [-2.15, -0.30]3.04 [1.65, 3.95]27% [11%, 45%]57%77%——2026-08-01 → 2026-08-30
tmax00Zbilinear365d30 1 QC2.33 [1.22, 3.47]2.14-1.23 [-2.25, -0.28]3.04 [1.43, 4.06]27% [9%, 46%]57%77%——2026-08-01 → 2026-08-30
tmax00Zbilinearall30 1 QC2.33 [1.35, 3.44]2.14-1.23 [-2.19, -0.24]3.04 [1.77, 4.03]27% [9%, 46%]57%77%——2026-08-01 → 2026-08-30
tmax00Znearest30d30 1 QC2.36 [1.67, 3.11]2.26-0.96 [-1.86, -0.03]2.96 [2.12, 3.66]20% [7%, 33%]50%73%——2026-08-01 → 2026-08-30
tmax00Znearest90d30 1 QC2.36 [1.43, 3.33]2.26-0.96 [-1.87, -0.01]2.96 [1.78, 3.79]20% [6%, 38%]50%73%——2026-08-01 → 2026-08-30
tmax00Znearest365d30 1 QC2.36 [1.36, 3.39]2.26-0.96 [-1.99, -0.01]2.96 [1.66, 3.87]20% [2%, 39%]50%73%——2026-08-01 → 2026-08-30
tmax00Znearestall30 1 QC2.36 [1.42, 3.39]2.26-0.96 [-1.90, -0.02]2.96 [1.77, 3.83]20% [5%, 38%]50%73%——2026-08-01 → 2026-08-30
tmin00Zbilinear30d30 1 QC1.72 [1.44, 1.98]1.64-0.42 [-1.30, 0.76]2.13 [1.75, 2.42]37% [27%, 47%]63%87%——2026-08-01 → 2026-08-30
tmin00Zbilinear90d30 1 QC1.72 [1.34, 2.09]1.64-0.42 [-1.42, 0.85]2.13 [1.66, 2.51]37% [27%, 46%]63%87%——2026-08-01 → 2026-08-30
tmin00Zbilinear365d30 1 QC1.72 [1.35, 2.12]1.64-0.42 [-1.53, 0.90]2.13 [1.62, 2.53]37% [27%, 47%]63%87%——2026-08-01 → 2026-08-30
tmin00Zbilinearall30 1 QC1.72 [1.29, 2.06]1.64-0.42 [-1.52, 0.98]2.13 [1.55, 2.49]37% [29%, 46%]63%87%——2026-08-01 → 2026-08-30
tmin00Znearest30d30 1 QC1.83 [1.52, 2.19]1.63-0.83 [-1.76, 0.47]2.29 [1.95, 2.58]37% [23%, 50%]57%80%——2026-08-01 → 2026-08-30
tmin00Znearest90d30 1 QC1.83 [1.38, 2.39]1.63-0.83 [-1.91, 0.53]2.29 [1.78, 2.79]37% [20%, 50%]57%80%——2026-08-01 → 2026-08-30
tmin00Znearest365d30 1 QC1.83 [1.37, 2.46]1.63-0.83 [-2.04, 0.58]2.29 [1.78, 2.86]37% [21%, 52%]57%80%——2026-08-01 → 2026-08-30
tmin00Znearestall30 1 QC1.83 [1.36, 2.37]1.63-0.83 [-2.01, 0.60]2.29 [1.75, 2.79]37% [21%, 50%]57%80%——2026-08-01 → 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 NCEP GFS at KDCA, lead day 0, 00Z bilinear tmax+10+50-5-102026-08-01: -4.18 °F2026-08-02: +3.59 °F2026-08-03: -5.87 °F2026-08-04: -1.65 °F2026-08-05: -7.14 °F2026-08-06: +2.81 °F2026-08-07: +2.32 °F2026-08-08: +1.55 °F2026-08-09: -0.72 °F2026-08-10: -0.08 °F2026-08-11: -1.72 °F2026-08-12: +1.06 °F2026-08-13: +0.25 °F2026-08-14: +0.46 °F2026-08-15: -1.5 °F2026-08-16: -2.29 °F2026-08-17: -7.31 °F2026-08-18: -3.99 °F2026-08-19: -1.65 °F2026-08-20: +0.58 °F2026-08-21: +1.39 °F2026-08-22: -5.87 °F2026-08-23: -2.53 °F2026-08-24: -1.34 °F2026-08-25: -2.3 °F2026-08-26: -0.84 °F2026-08-27: +2.47 °F2026-08-28: -0.71 °F2026-08-29: -1.16 °F2026-08-30: -0.5 °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
2026-08-30-0.50
2026-08-29-1.16
2026-08-28-0.71
2026-08-27+2.47
2026-08-26-0.84
2026-08-25-2.30
2026-08-24-1.34
2026-08-23-2.53
2026-08-22-5.87
2026-08-21+1.39
2026-08-20+0.58
2026-08-19-1.65
2026-08-18-3.99
2026-08-17-7.31
2026-08-16-2.29
2026-08-15-1.50
2026-08-14+0.46
2026-08-13+0.25
2026-08-12+1.06
2026-08-11-1.72
2026-08-10-0.08
2026-08-09-0.72
2026-08-08+1.55
2026-08-07+2.32
2026-08-06+2.81
2026-08-05-7.14
2026-08-04-1.65
2026-08-03-5.87
2026-08-02+3.59
2026-08-01-4.18

Error distribution

Distribution of the signed daily error in °F for NCEP GFS 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: 0 days-6 to -5 °F: 2 days-5 to -4 °F: 1 day-4 to -3 °F: 1 day-3 to -2 °F: 3 days-2 to -1 °F: 6 days-1 to 0 °F: 5 days0 to 1 °F: 3 days1 to 2 °F: 3 days2 to 3 °F: 3 days3 to 4 °F: 1 day4 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| 1.65 · P90 |e| 5.87 °F-100+10 °Fn = 30 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
-7.00-6.000
-6.00-5.002
-5.00-4.001
-4.00-3.001
-3.00-2.003
-2.00-1.006
-1.00+0.005
+0.00+1.003
+1.00+2.003
+2.00+3.003
+3.00+4.001
+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
2026-08302.33 -1.23

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-01 → 2026-08-30 30
NCEP GFS2026-08-01 → 2026-08-30 30

Compared with other models

Paired bootstrap on the days both models cover (90d, 00Z, bilinear, daily maximum). Negative means NCEP GFS has the lower MAE. "Distinguishable" means the 95 % interval excludes zero.

Other modelCommon days MAE difference °FDistinguishable
ECMWF AIFS Single 30 +0.15 [-0.95, 1.46] no
Aurora (GFS init) 2 -5.81 [-6.59, -5.04] yes
Aurora (IFS init) 3 -5.82 [-6.45, -5.50] yes
FourCastNet v2 (GFS init) 2 -3.31 [-3.98, -2.64] yes
FourCastNet v2 (IFS init) 3 -4.92 [-7.62, -3.56] yes
GraphCast (GFS init) 2 -5.11 [-5.59, -4.62] yes
GraphCast (IFS init) 28 -2.27 [-3.74, -1.01] yes
ECMWF IFS HRES 24 -1.00 [-1.64, 0.17] no
Pangu-Weather (GFS init) 2 -1.38 [-2.55, -0.22] yes
Pangu-Weather (IFS init) 3 -2.00 [-3.17, -1.42] yes

Cite this page

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

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KDCA (Washington Reagan), model gfs, 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/gfs/lead/0/

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

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