Raw model output on the native 0.25° grid — no MOS, no bias correction, no post-processing. Scores understate operational forecast quality. Read the fairness statement →

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

Washington Reagan · NCEP GFS · lead day 2

KDCA · gfs · 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, 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
tmax00Zbilinear30d28 1 QC3.00 [2.14, 3.99]2.82-1.60 [-2.89, -0.28]3.88 [2.55, 4.96]21% [7%, 37%]39%64%+0.12+0.172026-08-03 → 2026-08-30
tmax00Zbilinear90d28 1 QC3.00 [2.00, 4.17]2.82-1.60 [-3.19, -0.15]3.88 [2.38, 5.24]21% [4%, 43%]39%64%+0.12+0.172026-08-03 → 2026-08-30
tmax00Zbilinear365d28 1 QC3.00 [1.87, 4.34]2.82-1.60 [-3.30, 0.02]3.88 [2.29, 5.34]21% [0%, 46%]39%64%+0.12+0.172026-08-03 → 2026-08-30
tmax00Zbilinearall28 1 QC3.00 [1.89, 4.22]2.82-1.60 [-3.18, -0.00]3.88 [2.28, 5.27]21% [3%, 46%]39%64%+0.12+0.172026-08-03 → 2026-08-30
tmax00Znearest30d28 1 QC2.91 [2.09, 3.87]2.82-1.38 [-2.63, -0.10]3.74 [2.48, 4.80]25% [13%, 38%]39%50%+0.14+0.172026-08-03 → 2026-08-30
tmax00Znearest90d28 1 QC2.91 [1.92, 4.09]2.82-1.38 [-2.98, 0.08]3.74 [2.33, 5.04]25% [9%, 44%]39%50%+0.14+0.172026-08-03 → 2026-08-30
tmax00Znearest365d28 1 QC2.91 [1.80, 4.27]2.82-1.38 [-3.02, 0.19]3.74 [2.25, 5.17]25% [9%, 47%]39%50%+0.14+0.172026-08-03 → 2026-08-30
tmax00Znearestall28 1 QC2.91 [1.82, 4.19]2.82-1.38 [-2.98, 0.17]3.74 [2.23, 5.26]25% [8%, 47%]39%50%+0.14+0.172026-08-03 → 2026-08-30
tmax12Zbilinear30d28 1 QC3.21 [2.47, 4.04]3.13-1.26 [-2.86, 0.20]4.01 [2.99, 4.98]14% [3%, 32%]43%57%+0.05+0.082026-08-03 → 2026-08-30
tmax12Zbilinear90d28 1 QC3.21 [2.34, 4.18]3.13-1.26 [-3.04, 0.28]4.01 [2.89, 5.03]14% [0%, 36%]43%57%+0.05+0.082026-08-03 → 2026-08-30
tmax12Zbilinear365d28 1 QC3.21 [2.25, 4.29]3.13-1.26 [-3.34, 0.46]4.01 [2.77, 5.11]14% [0%, 41%]43%57%+0.05+0.082026-08-03 → 2026-08-30
tmax12Zbilinearall28 1 QC3.21 [2.29, 4.15]3.13-1.26 [-3.28, 0.36]4.01 [2.82, 5.01]14% [0%, 38%]43%57%+0.05+0.082026-08-03 → 2026-08-30
tmax12Znearest30d28 1 QC3.44 [2.60, 4.35]3.41-1.05 [-2.76, 0.63]4.41 [3.38, 5.31]14% [4%, 24%]39%57%-0.02-0.012026-08-03 → 2026-08-30
tmax12Znearest90d28 1 QC3.44 [2.46, 4.51]3.41-1.05 [-2.93, 0.69]4.41 [3.22, 5.42]14% [4%, 27%]39%57%-0.02-0.012026-08-03 → 2026-08-30
tmax12Znearest365d28 1 QC3.44 [2.38, 4.69]3.41-1.05 [-3.46, 0.90]4.41 [3.11, 5.47]14% [0%, 29%]39%57%-0.02-0.012026-08-03 → 2026-08-30
tmax12Znearestall28 1 QC3.44 [2.45, 4.52]3.41-1.05 [-3.18, 0.80]4.41 [3.15, 5.42]14% [0%, 29%]39%57%-0.02-0.012026-08-03 → 2026-08-30
tmin00Zbilinear30d28 1 QC2.83 [2.19, 3.55]2.69-1.22 [-2.75, 0.56]3.49 [2.62, 4.21]21% [13%, 33%]36%64%+0.16+0.212026-08-03 → 2026-08-30
tmin00Zbilinear90d28 1 QC2.83 [2.05, 3.54]2.69-1.22 [-2.76, 0.69]3.49 [2.40, 4.19]21% [11%, 33%]36%64%+0.16+0.212026-08-03 → 2026-08-30
tmin00Zbilinear365d28 1 QC2.83 [2.08, 3.63]2.69-1.22 [-2.87, 0.74]3.49 [2.40, 4.27]21% [10%, 35%]36%64%+0.16+0.212026-08-03 → 2026-08-30
tmin00Zbilinearall28 1 QC2.83 [2.04, 3.61]2.69-1.22 [-2.93, 1.08]3.49 [2.37, 4.28]21% [11%, 33%]36%64%+0.16+0.212026-08-03 → 2026-08-30
tmin00Znearest30d28 1 QC2.97 [2.28, 3.74]2.65-1.64 [-3.18, 0.21]3.65 [2.63, 4.45]21% [11%, 32%]36%64%+0.13+0.222026-08-03 → 2026-08-30
tmin00Znearest90d28 1 QC2.97 [2.20, 3.76]2.65-1.64 [-3.20, 0.34]3.65 [2.49, 4.51]21% [11%, 33%]36%64%+0.13+0.222026-08-03 → 2026-08-30
tmin00Znearest365d28 1 QC2.97 [2.19, 3.89]2.65-1.64 [-3.35, 0.41]3.65 [2.45, 4.58]21% [11%, 33%]36%64%+0.13+0.222026-08-03 → 2026-08-30
tmin00Znearestall28 1 QC2.97 [2.13, 3.89]2.65-1.64 [-3.47, 0.73]3.65 [2.45, 4.60]21% [11%, 33%]36%64%+0.13+0.222026-08-03 → 2026-08-30
tmin12Zbilinear30d28 1 QC2.50 [1.98, 3.04]2.40-0.59 [-1.92, 0.78]2.97 [2.34, 3.53]18% [10%, 27%]43%68%+0.26+0.292026-08-03 → 2026-08-30
tmin12Zbilinear90d28 1 QC2.50 [1.97, 3.07]2.40-0.59 [-2.09, 0.84]2.97 [2.32, 3.57]18% [8%, 27%]43%68%+0.26+0.292026-08-03 → 2026-08-30
tmin12Zbilinear365d28 1 QC2.50 [1.92, 3.08]2.40-0.59 [-2.25, 0.90]2.97 [2.25, 3.62]18% [6%, 27%]43%68%+0.26+0.292026-08-03 → 2026-08-30
tmin12Zbilinearall28 1 QC2.50 [1.90, 3.10]2.40-0.59 [-2.16, 1.07]2.97 [2.23, 3.61]18% [7%, 29%]43%68%+0.26+0.292026-08-03 → 2026-08-30
tmin12Znearest30d28 1 QC2.71 [2.11, 3.33]2.56-0.94 [-2.35, 0.50]3.20 [2.57, 3.77]18% [10%, 25%]32%57%+0.20+0.242026-08-03 → 2026-08-30
tmin12Znearest90d28 1 QC2.71 [2.11, 3.43]2.56-0.94 [-2.55, 0.61]3.20 [2.58, 3.86]18% [9%, 26%]32%57%+0.20+0.242026-08-03 → 2026-08-30
tmin12Znearest365d28 1 QC2.71 [2.01, 3.43]2.56-0.94 [-2.62, 0.65]3.20 [2.48, 3.85]18% [9%, 27%]32%57%+0.20+0.242026-08-03 → 2026-08-30
tmin12Znearestall28 1 QC2.71 [1.97, 3.46]2.56-0.94 [-2.63, 0.84]3.20 [2.44, 3.88]18% [10%, 29%]32%57%+0.20+0.242026-08-03 → 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 NCEP GFS at KDCA, lead day 2, 00Z bilinear tmax+20+100-10-202026-08-03: -9.95 °F2026-08-04: -2.82 °F2026-08-05: -4.75 °F2026-08-06: +2.66 °F2026-08-07: +2.35 °F2026-08-08: -0.06 °F2026-08-09: -2.2 °F2026-08-10: +3.22 °F2026-08-11: +1.93 °F2026-08-12: -0.59 °F2026-08-13: -0.32 °F2026-08-14: +2.91 °F2026-08-15: -3.24 °F2026-08-16: -4.51 °F2026-08-17: -4.63 °F2026-08-18: -1.67 °F2026-08-19: +1.2 °F2026-08-20: -10.83 °F2026-08-21: -4.39 °F2026-08-22: +2.83 °F2026-08-23: -2.71 °F2026-08-24: -4.06 °F2026-08-25: -1.46 °F2026-08-26: +0.65 °F2026-08-27: -1.95 °F2026-08-28: -4.27 °F2026-08-29: +0.89 °F2026-08-30: +0.89 °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+0.89
2026-08-29+0.89
2026-08-28-4.27
2026-08-27-1.95
2026-08-26+0.65
2026-08-25-1.46
2026-08-24-4.06
2026-08-23-2.71
2026-08-22+2.83
2026-08-21-4.39
2026-08-20-10.83
2026-08-19+1.20
2026-08-18-1.67
2026-08-17-4.63
2026-08-16-4.51
2026-08-15-3.24
2026-08-14+2.91
2026-08-13-0.32
2026-08-12-0.59
2026-08-11+1.93
2026-08-10+3.22
2026-08-09-2.20
2026-08-08-0.06
2026-08-07+2.35
2026-08-06+2.66
2026-08-05-4.75
2026-08-04-2.82
2026-08-03-9.95

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KDCA, lead day 2-20 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: 1 day-10 to -8 °F: 1 day-8 to -6 °F: 0 days-6 to -4 °F: 6 days-4 to -2 °F: 4 days-2 to 0 °F: 6 days0 to 2 °F: 5 days2 to 4 °F: 5 days4 to 6 °F: 0 days6 to 8 °F: 0 days8 to 10 °F: 0 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| 2.69 · P90 |e| 4.66 °F-200+20 °Fn = 28 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
-12.00-10.001
-10.00-8.001
-8.00-6.000
-6.00-4.006
-4.00-2.004
-2.00+0.006
+0.00+2.005
+2.00+4.005
+4.00+6.000
+6.00+8.000
+8.00+10.000
+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
2026-08283.00 -1.60

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-03 → 2026-08-30 28
NCEP GFS2026-08-03 → 2026-08-30 28
NCEP GFS2026-08-03 → 2026-08-30 28
NCEP GFS2026-08-03 → 2026-08-30 28

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 28 +0.43 [-0.28, 1.15] no
Aurora (IFS init) 1 -6.87 [-6.87, -6.87] yes
FourCastNet v2 (IFS init) 1 -2.00 [-2.00, -2.00] yes
GraphCast (IFS init) 26 -1.75 [-2.88, -0.89] yes
ECMWF IFS HRES 22 -1.03 [-1.90, 0.45] no
Pangu-Weather (IFS init) 1 -2.81 [-2.81, -2.81] yes
Persistence (baseline) 28 -0.39 [-1.41, 1.51] no

Cite this page

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

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