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 7

KATL · gfs · lead 7

Target day = initialization date + 7 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
tmax00Zbilinear30d23 1 QC2.98 [1.83, 4.17]2.99-0.54 [-2.34, 1.55]4.61 [2.46, 6.47]30% [14%, 44%]52%74%+0.23+0.202026-08-08 → 2026-08-30
tmax00Zbilinear90d23 1 QC2.98 [1.80, 4.26]2.99-0.54 [-2.63, 1.95]4.61 [2.37, 6.62]30% [10%, 44%]52%74%+0.23+0.202026-08-08 → 2026-08-30
tmax00Zbilinear365d23 1 QC2.98 [1.80, 4.25]2.99-0.54 [-2.61, 1.95]4.61 [2.38, 6.79]30% [10%, 44%]52%74%+0.23+0.202026-08-08 → 2026-08-30
tmax00Zbilinearall23 1 QC2.98 [1.77, 4.33]2.99-0.54 [-2.62, 2.03]4.61 [2.32, 6.82]30% [8%, 45%]52%74%+0.23+0.202026-08-08 → 2026-08-30
tmax00Znearest30d23 1 QC2.89 [1.94, 3.99]2.88+0.03 [-1.75, 2.00]4.22 [2.35, 5.83]22% [6%, 37%]48%70%+0.25+0.232026-08-08 → 2026-08-30
tmax00Znearest90d23 1 QC2.89 [1.89, 4.01]2.88+0.03 [-1.93, 2.30]4.22 [2.30, 5.96]22% [0%, 38%]48%70%+0.25+0.232026-08-08 → 2026-08-30
tmax00Znearest365d23 1 QC2.89 [1.90, 4.02]2.88+0.03 [-2.04, 2.35]4.22 [2.30, 5.97]22% [0%, 38%]48%70%+0.25+0.232026-08-08 → 2026-08-30
tmax00Znearestall23 1 QC2.89 [1.90, 4.05]2.88+0.03 [-2.06, 2.32]4.22 [2.30, 5.99]22% [0%, 38%]48%70%+0.25+0.232026-08-08 → 2026-08-30
tmax12Zbilinear30d23 1 QC2.74 [1.49, 4.04]2.82-0.66 [-2.38, 1.05]4.11 [2.04, 5.64]22% [5%, 41%]52%78%+0.29+0.252026-08-08 → 2026-08-30
tmax12Zbilinear90d23 1 QC2.74 [1.41, 4.10]2.82-0.66 [-2.64, 1.25]4.11 [1.98, 5.71]22% [0%, 43%]52%78%+0.29+0.252026-08-08 → 2026-08-30
tmax12Zbilinear365d23 1 QC2.74 [1.32, 4.10]2.82-0.66 [-2.54, 1.45]4.11 [1.84, 5.72]22% [0%, 43%]52%78%+0.29+0.252026-08-08 → 2026-08-30
tmax12Zbilinearall23 1 QC2.74 [1.19, 4.12]2.82-0.66 [-2.64, 1.32]4.11 [1.55, 5.76]22% [0%, 43%]52%78%+0.29+0.252026-08-08 → 2026-08-30
tmax12Znearest30d23 1 QC2.69 [1.43, 4.01]2.74-0.37 [-1.96, 1.29]4.09 [1.90, 5.66]30% [7%, 57%]61%78%+0.30+0.272026-08-08 → 2026-08-30
tmax12Znearest90d23 1 QC2.69 [1.31, 4.14]2.74-0.37 [-2.27, 1.42]4.09 [1.67, 5.73]30% [0%, 59%]61%78%+0.30+0.272026-08-08 → 2026-08-30
tmax12Znearest365d23 1 QC2.69 [1.28, 4.13]2.74-0.37 [-2.16, 1.65]4.09 [1.50, 5.74]30% [0%, 62%]61%78%+0.30+0.272026-08-08 → 2026-08-30
tmax12Znearestall23 1 QC2.69 [1.12, 4.17]2.74-0.37 [-2.27, 1.54]4.09 [1.32, 5.74]30% [0%, 67%]61%78%+0.30+0.272026-08-08 → 2026-08-30
tmin00Zbilinear30d23 1 QC2.70 [1.69, 3.56]2.51+1.08 [0.05, 2.31]3.30 [2.11, 4.06]22% [0%, 48%]52%57%-0.09-0.012026-08-08 → 2026-08-30
tmin00Zbilinear90d23 1 QC2.70 [1.58, 3.55]2.51+1.08 [0.03, 2.47]3.30 [1.93, 4.07]22% [0%, 50%]52%57%-0.09-0.012026-08-08 → 2026-08-30
tmin00Zbilinear365d23 1 QC2.70 [1.55, 3.61]2.51+1.08 [0.04, 2.51]3.30 [1.90, 4.13]22% [0%, 53%]52%57%-0.09-0.012026-08-08 → 2026-08-30
tmin00Zbilinearall23 1 QC2.70 [1.53, 3.62]2.51+1.08 [-0.05, 2.50]3.30 [1.86, 4.10]22% [0%, 57%]52%57%-0.09-0.012026-08-08 → 2026-08-30
tmin00Znearest30d23 1 QC3.44 [2.29, 4.38]2.83+2.27 [1.02, 3.77]4.19 [3.08, 5.02]22% [0%, 43%]35%48%-0.39-0.142026-08-08 → 2026-08-30
tmin00Znearest90d23 1 QC3.44 [2.06, 4.39]2.83+2.27 [0.99, 3.93]4.19 [2.86, 5.11]22% [0%, 47%]35%48%-0.39-0.142026-08-08 → 2026-08-30
tmin00Znearest365d23 1 QC3.44 [2.04, 4.44]2.83+2.27 [1.06, 4.01]4.19 [2.83, 5.11]22% [0%, 47%]35%48%-0.39-0.142026-08-08 → 2026-08-30
tmin00Znearestall23 1 QC3.44 [2.04, 4.41]2.83+2.27 [0.88, 4.01]4.19 [2.73, 5.06]22% [0%, 46%]35%48%-0.39-0.142026-08-08 → 2026-08-30
tmin12Zbilinear30d23 1 QC2.33 [1.58, 3.16]2.20+0.92 [-0.52, 2.34]3.05 [1.95, 4.01]26% [7%, 50%]52%74%+0.06+0.122026-08-08 → 2026-08-30
tmin12Zbilinear90d23 1 QC2.33 [1.51, 3.26]2.20+0.92 [-0.83, 2.66]3.05 [1.85, 4.07]26% [4%, 54%]52%74%+0.06+0.122026-08-08 → 2026-08-30
tmin12Zbilinear365d23 1 QC2.33 [1.45, 3.40]2.20+0.92 [-0.87, 2.72]3.05 [1.82, 4.26]26% [0%, 56%]52%74%+0.06+0.122026-08-08 → 2026-08-30
tmin12Zbilinearall23 1 QC2.33 [1.49, 3.25]2.20+0.92 [-0.86, 2.47]3.05 [1.81, 4.09]26% [0%, 56%]52%74%+0.06+0.122026-08-08 → 2026-08-30
tmin12Znearest30d23 1 QC3.04 [1.87, 4.48]2.62+2.21 [0.49, 4.06]3.96 [2.23, 5.40]26% [10%, 43%]43%52%-0.23-0.062026-08-08 → 2026-08-30
tmin12Znearest90d23 1 QC3.04 [1.79, 4.65]2.62+2.21 [0.06, 4.31]3.96 [1.99, 5.51]26% [6%, 46%]43%52%-0.23-0.062026-08-08 → 2026-08-30
tmin12Znearest365d23 1 QC3.04 [1.73, 4.87]2.62+2.21 [0.07, 4.45]3.96 [1.94, 5.72]26% [3%, 50%]43%52%-0.23-0.062026-08-08 → 2026-08-30
tmin12Znearestall23 1 QC3.04 [1.72, 4.52]2.62+2.21 [-0.05, 4.11]3.96 [1.91, 5.43]26% [6%, 45%]43%52%-0.23-0.062026-08-08 → 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 7, 00Z bilinear tmax+20+100-10-202026-08-08: +1.02 °F2026-08-09: +1.47 °F2026-08-10: -1.27 °F2026-08-11: -5.92 °F2026-08-12: -0.62 °F2026-08-13: -2.71 °F2026-08-14: -16.64 °F2026-08-15: -0.77 °F2026-08-16: +2.61 °F2026-08-17: -0.27 °F2026-08-18: +7.79 °F2026-08-19: +2.72 °F2026-08-20: +3.59 °F2026-08-21: +0.82 °F2026-08-22: -2.7 °F2026-08-23: -1.98 °F2026-08-24: -6.16 °F2026-08-25: -1.1 °F2026-08-26: +0.33 °F2026-08-27: +0.92 °F2026-08-28: -0.38 °F2026-08-29: +2.33 °F2026-08-30: +4.36 °F2026-08-082026-08-30°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 (23 days, newest first) · download CSV
Climatological dayError °F
2026-08-30+4.36
2026-08-29+2.33
2026-08-28-0.38
2026-08-27+0.92
2026-08-26+0.33
2026-08-25-1.10
2026-08-24-6.16
2026-08-23-1.98
2026-08-22-2.70
2026-08-21+0.82
2026-08-20+3.59
2026-08-19+2.72
2026-08-18+7.79
2026-08-17-0.27
2026-08-16+2.61
2026-08-15-0.77
2026-08-14-16.64
2026-08-13-2.71
2026-08-12-0.62
2026-08-11-5.92
2026-08-10-1.27
2026-08-09+1.47
2026-08-08+1.02

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KATL, lead day 7-20 to -18 °F: 0 days-18 to -16 °F: 1 day-16 to -14 °F: 0 days-14 to -12 °F: 0 days-12 to -10 °F: 0 days-10 to -8 °F: 0 days-8 to -6 °F: 1 day-6 to -4 °F: 1 day-4 to -2 °F: 2 days-2 to 0 °F: 7 days0 to 2 °F: 5 days2 to 4 °F: 4 days4 to 6 °F: 1 day6 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| 1.98 · P90 |e| 6.11 °F-200+20 °Fn = 23 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
-18.00-16.001
-16.00-14.000
-14.00-12.000
-12.00-10.000
-10.00-8.000
-8.00-6.001
-6.00-4.001
-4.00-2.002
-2.00+0.007
+0.00+2.005
+2.00+4.004
+4.00+6.001
+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
2026-08232.98 -0.54

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-08 → 2026-08-30 23
NCEP GFS2026-08-08 → 2026-08-30 23
NCEP GFS2026-08-08 → 2026-08-30 23
NCEP GFS2026-08-08 → 2026-08-30 23

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 23 -1.90 [-4.51, 0.09] no
GraphCast (IFS init) 23 -2.44 [-5.91, -0.08] yes
ECMWF IFS HRES 18 -0.34 [-2.61, 2.24] no
Persistence (baseline) 23 -0.89 [-2.65, 0.47] no

Cite this page

ShortCastCheck, KATL gfs lead 7, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KATL/model/gfs/lead/7/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KATL (Atlanta Hartsfield), model gfs, lead day 7. 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/7/

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