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

Atlanta Hartsfield · NCEP GFS · lead day 1

KATL · gfs · lead 1

Target day = initialization date + 1 day. 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
tmax00Zbilinear30d29 1 QC2.45 [1.74, 3.50]2.53-0.88 [-2.49, 0.67]3.49 [2.19, 4.91]28% [13%, 43%]62%72%-0.11-0.142026-08-02 → 2026-08-30
tmax00Zbilinear90d29 1 QC2.45 [1.77, 3.72]2.53-0.88 [-2.97, 0.45]3.49 [2.21, 5.19]28% [11%, 44%]62%72%-0.11-0.142026-08-02 → 2026-08-30
tmax00Zbilinear365d29 1 QC2.45 [1.71, 3.56]2.53-0.88 [-2.76, 0.64]3.49 [2.14, 5.05]28% [7%, 44%]62%72%-0.11-0.142026-08-02 → 2026-08-30
tmax00Zbilinearall29 1 QC2.45 [1.72, 3.70]2.53-0.88 [-3.04, 0.60]3.49 [2.15, 5.38]28% [9%, 47%]62%72%-0.11-0.142026-08-02 → 2026-08-30
tmax00Znearest30d29 1 QC2.15 [1.50, 2.99]2.15-0.18 [-1.77, 1.34]2.81 [1.84, 3.92]28% [12%, 41%]52%76%+0.03+0.032026-08-02 → 2026-08-30
tmax00Znearest90d29 1 QC2.15 [1.53, 3.13]2.15-0.18 [-2.13, 1.15]2.81 [1.83, 4.13]28% [11%, 42%]52%76%+0.03+0.032026-08-02 → 2026-08-30
tmax00Znearest365d29 1 QC2.15 [1.47, 3.07]2.15-0.18 [-2.02, 1.29]2.81 [1.78, 4.11]28% [9%, 43%]52%76%+0.03+0.032026-08-02 → 2026-08-30
tmax00Znearestall29 1 QC2.15 [1.43, 3.13]2.15-0.18 [-2.25, 1.24]2.81 [1.67, 4.30]28% [9%, 43%]52%76%+0.03+0.032026-08-02 → 2026-08-30
tmax12Zbilinear30d29 1 QC2.19 [1.64, 2.83]2.06+0.27 [-0.96, 1.52]3.04 [1.91, 4.00]24% [10%, 38%]66%83%+0.01+0.072026-08-02 → 2026-08-30
tmax12Zbilinear90d29 1 QC2.19 [1.55, 3.01]2.06+0.27 [-1.23, 1.37]3.04 [1.85, 4.27]24% [12%, 40%]66%83%+0.01+0.072026-08-02 → 2026-08-30
tmax12Zbilinear365d29 1 QC2.19 [1.53, 3.03]2.06+0.27 [-1.17, 1.47]3.04 [1.74, 4.25]24% [10%, 43%]66%83%+0.01+0.072026-08-02 → 2026-08-30
tmax12Zbilinearall29 1 QC2.19 [1.56, 3.10]2.06+0.27 [-1.50, 1.47]3.04 [1.80, 4.45]24% [12%, 42%]66%83%+0.01+0.072026-08-02 → 2026-08-30
tmax12Znearest30d29 1 QC2.19 [1.70, 2.67]1.91+0.82 [-0.40, 1.93]3.02 [2.07, 3.97]28% [10%, 44%]55%79%+0.01+0.142026-08-02 → 2026-08-30
tmax12Znearest90d29 1 QC2.19 [1.42, 2.99]1.91+0.82 [-0.67, 1.85]3.02 [1.82, 4.43]28% [12%, 50%]55%79%+0.01+0.142026-08-02 → 2026-08-30
tmax12Znearest365d29 1 QC2.19 [1.36, 2.98]1.91+0.82 [-0.69, 1.98]3.02 [1.75, 4.34]28% [10%, 50%]55%79%+0.01+0.142026-08-02 → 2026-08-30
tmax12Znearestall29 1 QC2.19 [1.51, 3.02]1.91+0.82 [-1.03, 1.92]3.02 [1.88, 4.54]28% [11%, 50%]55%79%+0.01+0.142026-08-02 → 2026-08-30
tmin00Zbilinear30d29 1 QC2.15 [1.43, 2.95]1.77+1.42 [0.13, 2.74]2.67 [1.63, 3.50]21% [10%, 33%]55%79%-0.13+0.062026-08-02 → 2026-08-30
tmin00Zbilinear90d29 1 QC2.15 [1.34, 2.92]1.77+1.42 [-0.23, 2.56]2.67 [1.54, 3.45]21% [7%, 33%]55%79%-0.13+0.062026-08-02 → 2026-08-30
tmin00Zbilinear365d29 1 QC2.15 [1.32, 3.07]1.77+1.42 [-0.27, 2.77]2.67 [1.51, 3.56]21% [7%, 34%]55%79%-0.13+0.062026-08-02 → 2026-08-30
tmin00Zbilinearall29 1 QC2.15 [1.35, 2.97]1.77+1.42 [-0.29, 2.70]2.67 [1.55, 3.52]21% [7%, 33%]55%79%-0.13+0.062026-08-02 → 2026-08-30
tmin00Znearest30d29 1 QC2.90 [1.83, 4.04]1.94+2.52 [1.04, 3.96]3.53 [2.14, 4.60]21% [7%, 37%]38%62%-0.53-0.032026-08-02 → 2026-08-30
tmin00Znearest90d29 1 QC2.90 [1.61, 3.95]1.94+2.52 [0.71, 3.81]3.53 [1.98, 4.50]21% [6%, 45%]38%62%-0.53-0.032026-08-02 → 2026-08-30
tmin00Znearest365d29 1 QC2.90 [1.59, 4.14]1.94+2.52 [0.63, 3.98]3.53 [1.93, 4.66]21% [5%, 47%]38%62%-0.53-0.032026-08-02 → 2026-08-30
tmin00Znearestall29 1 QC2.90 [1.60, 4.04]1.94+2.52 [0.53, 3.94]3.53 [1.97, 4.59]21% [5%, 47%]38%62%-0.53-0.032026-08-02 → 2026-08-30
tmin12Zbilinear30d29 1 QC2.17 [1.63, 2.86]1.81+1.58 [0.61, 2.66]2.69 [1.86, 3.45]31% [21%, 40%]52%69%-0.14+0.042026-08-02 → 2026-08-30
tmin12Zbilinear90d29 1 QC2.17 [1.46, 2.80]1.81+1.58 [0.37, 2.52]2.69 [1.70, 3.38]31% [20%, 43%]52%69%-0.14+0.042026-08-02 → 2026-08-30
tmin12Zbilinear365d29 1 QC2.17 [1.42, 2.90]1.81+1.58 [0.40, 2.62]2.69 [1.64, 3.49]31% [18%, 43%]52%69%-0.14+0.042026-08-02 → 2026-08-30
tmin12Zbilinearall29 1 QC2.17 [1.50, 2.86]1.81+1.58 [0.28, 2.59]2.69 [1.71, 3.46]31% [19%, 43%]52%69%-0.14+0.042026-08-02 → 2026-08-30
tmin12Znearest30d29 1 QC2.98 [2.19, 3.86]1.81+2.81 [1.80, 3.81]3.58 [2.73, 4.39]21% [7%, 36%]38%52%-0.57+0.042026-08-02 → 2026-08-30
tmin12Znearest90d29 1 QC2.98 [1.91, 3.78]1.81+2.81 [1.53, 3.69]3.58 [2.47, 4.30]21% [5%, 45%]38%52%-0.57+0.042026-08-02 → 2026-08-30
tmin12Znearest365d29 1 QC2.98 [1.83, 3.92]1.81+2.81 [1.54, 3.80]3.58 [2.42, 4.44]21% [5%, 46%]38%52%-0.57+0.042026-08-02 → 2026-08-30
tmin12Znearestall29 1 QC2.98 [1.94, 3.91]1.81+2.81 [1.48, 3.78]3.58 [2.45, 4.41]21% [4%, 45%]38%52%-0.57+0.042026-08-02 → 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 1, 00Z bilinear tmax+20+100-10-202026-08-02: -11.82 °F2026-08-03: -0.9 °F2026-08-04: -0.13 °F2026-08-05: -1.29 °F2026-08-06: +2.19 °F2026-08-07: -3.83 °F2026-08-08: +0.61 °F2026-08-09: -0.41 °F2026-08-10: -3.23 °F2026-08-11: +1.6 °F2026-08-12: +1.41 °F2026-08-13: +1.19 °F2026-08-14: +2.75 °F2026-08-15: +1.34 °F2026-08-16: +2.6 °F2026-08-17: +1.62 °F2026-08-18: +3.4 °F2026-08-19: -0.8 °F2026-08-20: -6.9 °F2026-08-21: -1.75 °F2026-08-22: -0.5 °F2026-08-23: +0.25 °F2026-08-24: -1.17 °F2026-08-25: +0.64 °F2026-08-26: +1.14 °F2026-08-27: +1.99 °F2026-08-28: -7.19 °F2026-08-29: -4.65 °F2026-08-30: -3.67 °F2026-08-022026-08-30°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 (29 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-3.67
2026-08-29-4.65
2026-08-28-7.19
2026-08-27+1.99
2026-08-26+1.14
2026-08-25+0.64
2026-08-24-1.17
2026-08-23+0.25
2026-08-22-0.50
2026-08-21-1.75
2026-08-20-6.90
2026-08-19-0.80
2026-08-18+3.40
2026-08-17+1.62
2026-08-16+2.60
2026-08-15+1.34
2026-08-14+2.75
2026-08-13+1.19
2026-08-12+1.41
2026-08-11+1.60
2026-08-10-3.23
2026-08-09-0.41
2026-08-08+0.61
2026-08-07-3.83
2026-08-06+2.19
2026-08-05-1.29
2026-08-04-0.13
2026-08-03-0.90
2026-08-02-11.82

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KATL, lead day 1-20 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: 0 days-8 to -6 °F: 2 days-6 to -4 °F: 1 day-4 to -2 °F: 3 days-2 to 0 °F: 8 days0 to 2 °F: 10 days2 to 4 °F: 4 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| 1.6 · P90 |e| 5.1 °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
-12.00-10.001
-10.00-8.000
-8.00-6.002
-6.00-4.001
-4.00-2.003
-2.00+0.008
+0.00+2.0010
+2.00+4.004
+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
2026-08292.45 -0.88

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-02 → 2026-08-30 29
NCEP GFS2026-08-02 → 2026-08-30 29
NCEP GFS2026-08-02 → 2026-08-30 29
NCEP GFS2026-08-02 → 2026-08-30 29

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 29 -1.86 [-2.71, -0.77] yes
Aurora (GFS init) 1 -3.44 [-3.44, -3.44] yes
Aurora (IFS init) 2 -2.10 [-2.52, -1.67] yes
FourCastNet v2 (GFS init) 1 +0.23 [0.23, 0.23] yes
FourCastNet v2 (IFS init) 2 +1.38 [1.05, 1.71] yes
GraphCast (GFS init) 1 -2.52 [-2.52, -2.52] yes
GraphCast (IFS init) 27 -3.64 [-4.61, -2.42] yes
ECMWF IFS HRES 23 +0.61 [-0.30, 2.08] no
Pangu-Weather (GFS init) 1 -0.31 [-0.31, -0.31] yes
Pangu-Weather (IFS init) 2 +1.30 [0.69, 1.91] yes
Persistence (baseline) 29 +0.24 [-0.36, 0.97] no

Cite this page

ShortCastCheck, KATL gfs lead 1, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KATL/model/gfs/lead/1/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KATL (Atlanta Hartsfield), model gfs, lead day 1. 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/1/

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

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