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

Atlanta Hartsfield · NCEP GFS · lead day 3

KATL · gfs · lead 3

Target day = initialization date + 3 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
tmax00Zbilinear30d27 1 QC2.94 [2.13, 3.73]2.91+0.15 [-1.90, 2.15]4.09 [2.50, 5.63]22% [10%, 39%]44%67%-0.50-0.472026-08-04 → 2026-08-30
tmax00Zbilinear90d27 1 QC2.94 [2.07, 3.78]2.91+0.15 [-2.02, 2.15]4.09 [2.48, 5.57]22% [10%, 45%]44%67%-0.50-0.472026-08-04 → 2026-08-30
tmax00Zbilinear365d27 1 QC2.94 [2.06, 3.84]2.91+0.15 [-2.34, 2.55]4.09 [2.47, 5.84]22% [8%, 50%]44%67%-0.50-0.472026-08-04 → 2026-08-30
tmax00Zbilinearall27 1 QC2.94 [2.01, 3.82]2.91+0.15 [-2.11, 2.48]4.09 [2.45, 5.87]22% [10%, 50%]44%67%-0.50-0.472026-08-04 → 2026-08-30
tmax00Znearest30d27 1 QC2.86 [2.06, 3.62]2.52+0.87 [-1.10, 2.67]3.79 [2.50, 4.89]11% [0%, 24%]44%70%-0.46-0.282026-08-04 → 2026-08-30
tmax00Znearest90d27 1 QC2.86 [1.99, 3.64]2.52+0.87 [-1.20, 2.71]3.79 [2.42, 4.90]11% [0%, 26%]44%70%-0.46-0.282026-08-04 → 2026-08-30
tmax00Znearest365d27 1 QC2.86 [1.96, 3.65]2.52+0.87 [-1.46, 3.06]3.79 [2.38, 5.04]11% [0%, 26%]44%70%-0.46-0.282026-08-04 → 2026-08-30
tmax00Znearestall27 1 QC2.86 [1.95, 3.63]2.52+0.87 [-1.26, 2.96]3.79 [2.36, 5.06]11% [0%, 27%]44%70%-0.46-0.282026-08-04 → 2026-08-30
tmax12Zbilinear30d27 1 QC2.94 [1.63, 4.51]3.08-0.45 [-2.99, 1.66]4.49 [2.18, 6.77]30% [11%, 52%]52%63%-0.50-0.562026-08-04 → 2026-08-30
tmax12Zbilinear90d27 1 QC2.94 [1.49, 4.80]3.08-0.45 [-3.80, 1.64]4.49 [1.91, 7.15]30% [10%, 55%]52%63%-0.50-0.562026-08-04 → 2026-08-30
tmax12Zbilinear365d27 1 QC2.94 [1.48, 4.89]3.08-0.45 [-4.11, 1.88]4.49 [1.86, 7.27]30% [7%, 54%]52%63%-0.50-0.562026-08-04 → 2026-08-30
tmax12Zbilinearall27 1 QC2.94 [1.43, 4.67]3.08-0.45 [-3.52, 1.69]4.49 [1.82, 6.94]30% [7%, 56%]52%63%-0.50-0.562026-08-04 → 2026-08-30
tmax12Znearest30d27 1 QC3.11 [1.77, 4.87]3.13-0.07 [-2.98, 2.21]4.78 [2.24, 7.44]15% [4%, 29%]52%63%-0.58-0.592026-08-04 → 2026-08-30
tmax12Znearest90d27 1 QC3.11 [1.54, 5.11]3.13-0.07 [-3.83, 2.21]4.78 [1.94, 7.81]15% [0%, 29%]52%63%-0.58-0.592026-08-04 → 2026-08-30
tmax12Znearest365d27 1 QC3.11 [1.48, 5.25]3.13-0.07 [-4.31, 2.47]4.78 [1.87, 8.01]15% [0%, 31%]52%63%-0.58-0.592026-08-04 → 2026-08-30
tmax12Znearestall27 1 QC3.11 [1.42, 5.09]3.13-0.07 [-3.57, 2.33]4.78 [1.79, 7.58]15% [0%, 31%]52%63%-0.58-0.592026-08-04 → 2026-08-30
tmin00Zbilinear30d27 1 QC2.40 [1.25, 3.52]2.11+1.70 [0.29, 3.06]3.08 [1.55, 4.13]22% [13%, 39%]56%74%-0.25-0.092026-08-04 → 2026-08-30
tmin00Zbilinear90d27 1 QC2.40 [1.12, 3.46]2.11+1.70 [-0.04, 3.08]3.08 [1.38, 4.05]22% [14%, 40%]56%74%-0.25-0.092026-08-04 → 2026-08-30
tmin00Zbilinear365d27 1 QC2.40 [1.08, 3.65]2.11+1.70 [-0.13, 3.31]3.08 [1.37, 4.24]22% [13%, 40%]56%74%-0.25-0.092026-08-04 → 2026-08-30
tmin00Zbilinearall27 1 QC2.40 [0.96, 3.55]2.11+1.70 [-0.03, 3.19]3.08 [1.23, 4.14]22% [14%, 45%]56%74%-0.25-0.092026-08-04 → 2026-08-30
tmin00Znearest30d27 1 QC3.12 [1.83, 4.39]2.28+2.90 [1.42, 4.35]3.98 [2.30, 5.18]26% [15%, 35%]41%56%-0.62-0.182026-08-04 → 2026-08-30
tmin00Znearest90d27 1 QC3.12 [1.58, 4.41]2.28+2.90 [1.13, 4.35]3.98 [1.99, 5.13]26% [14%, 35%]41%56%-0.62-0.182026-08-04 → 2026-08-30
tmin00Znearest365d27 1 QC3.12 [1.55, 4.62]2.28+2.90 [1.04, 4.55]3.98 [1.97, 5.33]26% [13%, 36%]41%56%-0.62-0.182026-08-04 → 2026-08-30
tmin00Znearestall27 1 QC3.12 [1.54, 4.50]2.28+2.90 [1.16, 4.43]3.98 [1.90, 5.24]26% [14%, 36%]41%56%-0.62-0.182026-08-04 → 2026-08-30
tmin12Zbilinear30d27 1 QC2.22 [1.44, 2.84]2.13+1.39 [0.27, 2.30]2.85 [1.90, 3.44]33% [23%, 48%]48%70%-0.15-0.112026-08-04 → 2026-08-30
tmin12Zbilinear90d27 1 QC2.22 [1.22, 2.80]2.13+1.39 [-0.08, 2.33]2.85 [1.58, 3.42]33% [24%, 50%]48%70%-0.15-0.112026-08-04 → 2026-08-30
tmin12Zbilinear365d27 1 QC2.22 [1.26, 2.88]2.13+1.39 [-0.11, 2.39]2.85 [1.64, 3.51]33% [23%, 50%]48%70%-0.15-0.112026-08-04 → 2026-08-30
tmin12Zbilinearall27 1 QC2.22 [1.09, 2.77]2.13+1.39 [-0.07, 2.35]2.85 [1.43, 3.43]33% [24%, 53%]48%70%-0.15-0.112026-08-04 → 2026-08-30
tmin12Znearest30d27 1 QC3.08 [2.12, 3.82]2.26+2.75 [1.53, 3.70]3.83 [2.69, 4.53]22% [7%, 38%]44%59%-0.60-0.182026-08-04 → 2026-08-30
tmin12Znearest90d27 1 QC3.08 [1.93, 3.82]2.26+2.75 [1.18, 3.76]3.83 [2.29, 4.53]22% [6%, 42%]44%59%-0.60-0.182026-08-04 → 2026-08-30
tmin12Znearest365d27 1 QC3.08 [1.98, 3.90]2.26+2.75 [1.18, 3.85]3.83 [2.33, 4.59]22% [6%, 43%]44%59%-0.60-0.182026-08-04 → 2026-08-30
tmin12Znearestall27 1 QC3.08 [1.75, 3.83]2.26+2.75 [0.99, 3.78]3.83 [2.10, 4.54]22% [5%, 46%]44%59%-0.60-0.182026-08-04 → 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 KATL, lead day 3, 00Z bilinear tmax+20+100-10-202026-08-04: +2.51 °F2026-08-05: -0.48 °F2026-08-06: -2.05 °F2026-08-07: +3.85 °F2026-08-08: -2.87 °F2026-08-09: +1.47 °F2026-08-10: -3.57 °F2026-08-11: -1.25 °F2026-08-12: +1.88 °F2026-08-13: +0.74 °F2026-08-14: +4.71 °F2026-08-15: +3.75 °F2026-08-16: +1.99 °F2026-08-17: +3.11 °F2026-08-18: +6.39 °F2026-08-19: +2.64 °F2026-08-20: +4.66 °F2026-08-21: -1.12 °F2026-08-22: +0.8 °F2026-08-23: +1.59 °F2026-08-24: -15.25 °F2026-08-25: -2.6 °F2026-08-26: +0.91 °F2026-08-27: -2.58 °F2026-08-28: -5.17 °F2026-08-29: -0.64 °F2026-08-30: +0.69 °F2026-08-042026-08-30°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 (27 days, newest first) · download CSV
Climatological dayError °F
2026-08-30+0.69
2026-08-29-0.64
2026-08-28-5.17
2026-08-27-2.58
2026-08-26+0.91
2026-08-25-2.60
2026-08-24-15.25
2026-08-23+1.59
2026-08-22+0.80
2026-08-21-1.12
2026-08-20+4.66
2026-08-19+2.64
2026-08-18+6.39
2026-08-17+3.11
2026-08-16+1.99
2026-08-15+3.75
2026-08-14+4.71
2026-08-13+0.74
2026-08-12+1.88
2026-08-11-1.25
2026-08-10-3.57
2026-08-09+1.47
2026-08-08-2.87
2026-08-07+3.85
2026-08-06-2.05
2026-08-05-0.48
2026-08-04+2.51

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KATL, lead day 3-20 to -18 °F: 0 days-18 to -16 °F: 0 days-16 to -14 °F: 1 day-14 to -12 °F: 0 days-12 to -10 °F: 0 days-10 to -8 °F: 0 days-8 to -6 °F: 0 days-6 to -4 °F: 1 day-4 to -2 °F: 5 days-2 to 0 °F: 4 days0 to 2 °F: 8 days2 to 4 °F: 5 days4 to 6 °F: 2 days6 to 8 °F: 1 day8 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| 2.51 · P90 |e| 4.89 °F-200+20 °Fn = 27 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
-16.00-14.001
-14.00-12.000
-12.00-10.000
-10.00-8.000
-8.00-6.000
-6.00-4.001
-4.00-2.005
-2.00+0.004
+0.00+2.008
+2.00+4.005
+4.00+6.002
+6.00+8.001
+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
2026-08272.94 +0.15

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-04 → 2026-08-30 27
NCEP GFS2026-08-04 → 2026-08-30 27
NCEP GFS2026-08-04 → 2026-08-30 27
NCEP GFS2026-08-04 → 2026-08-30 27

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 27 -1.36 [-2.66, -0.27] yes
GraphCast (IFS init) 25 -2.44 [-4.35, -0.66] yes
ECMWF IFS HRES 22 -0.18 [-1.37, 0.71] no
Persistence (baseline) 27 +0.97 [0.00, 1.89] yes

Cite this page

ShortCastCheck, KATL gfs lead 3, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KATL/model/gfs/lead/3/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KATL (Atlanta Hartsfield), model gfs, lead day 3. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KATL/model/gfs/lead/3/

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