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

Atlanta Hartsfield · NCEP GFS · lead day 9

KATL · gfs · lead 9

Target day = initialization date + 9 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
tmax00Zbilinear30d21 1 QC4.97 [3.67, 6.19]5.17-1.54 [-5.22, 1.93]6.09 [4.60, 7.29]19% [7%, 40%]29%38%-0.15-0.202026-08-10 → 2026-08-30
tmax00Zbilinear90d21 1 QC4.97 [3.42, 6.29]5.17-1.54 [-5.30, 2.08]6.09 [4.23, 7.35]19% [7%, 46%]29%38%-0.15-0.202026-08-10 → 2026-08-30
tmax00Zbilinear365d21 1 QC4.97 [3.41, 6.37]5.17-1.54 [-5.79, 2.36]6.09 [4.13, 7.41]19% [6%, 42%]29%38%-0.15-0.202026-08-10 → 2026-08-30
tmax00Zbilinearall21 1 QC4.97 [3.43, 6.56]5.17-1.54 [-5.84, 2.57]6.09 [4.13, 7.46]19% [0%, 42%]29%38%-0.15-0.202026-08-10 → 2026-08-30
tmax00Znearest30d21 1 QC5.16 [3.95, 6.43]5.35-1.38 [-5.37, 2.21]6.29 [4.87, 7.63]19% [7%, 33%]24%38%-0.19-0.242026-08-10 → 2026-08-30
tmax00Znearest90d21 1 QC5.16 [3.65, 6.47]5.35-1.38 [-5.66, 2.43]6.29 [4.50, 7.69]19% [7%, 33%]24%38%-0.19-0.242026-08-10 → 2026-08-30
tmax00Znearest365d21 1 QC5.16 [3.63, 6.60]5.35-1.38 [-5.95, 2.57]6.29 [4.39, 7.77]19% [7%, 33%]24%38%-0.19-0.242026-08-10 → 2026-08-30
tmax00Znearestall21 1 QC5.16 [3.67, 6.60]5.35-1.38 [-6.03, 2.81]6.29 [4.39, 7.73]19% [0%, 33%]24%38%-0.19-0.242026-08-10 → 2026-08-30
tmax12Zbilinear30d21 1 QC5.27 [3.92, 7.19]5.22-1.46 [-4.84, 1.09]6.65 [4.87, 8.76]14% [0%, 27%]19%38%-0.22-0.212026-08-10 → 2026-08-30
tmax12Zbilinear90d21 1 QC5.27 [3.80, 7.39]5.22-1.46 [-5.89, 1.59]6.65 [4.70, 9.23]14% [0%, 27%]19%38%-0.22-0.212026-08-10 → 2026-08-30
tmax12Zbilinear365d21 1 QC5.27 [3.65, 7.36]5.22-1.46 [-5.88, 1.85]6.65 [4.69, 9.14]14% [0%, 29%]19%38%-0.22-0.212026-08-10 → 2026-08-30
tmax12Zbilinearall21 1 QC5.27 [3.60, 7.34]5.22-1.46 [-5.89, 2.01]6.65 [4.66, 9.09]14% [0%, 29%]19%38%-0.22-0.212026-08-10 → 2026-08-30
tmax12Znearest30d21 1 QC5.51 [4.35, 7.18]5.51-1.27 [-4.64, 1.47]6.94 [5.51, 8.95]10% [0%, 18%]24%38%-0.27-0.282026-08-10 → 2026-08-30
tmax12Znearest90d21 1 QC5.51 [4.26, 7.47]5.51-1.27 [-5.73, 1.90]6.94 [5.34, 9.32]10% [0%, 18%]24%38%-0.27-0.282026-08-10 → 2026-08-30
tmax12Znearest365d21 1 QC5.51 [4.25, 7.27]5.51-1.27 [-5.65, 2.16]6.94 [5.31, 9.28]10% [0%, 18%]24%38%-0.27-0.282026-08-10 → 2026-08-30
tmax12Znearestall21 1 QC5.51 [4.23, 7.22]5.51-1.27 [-5.63, 2.18]6.94 [5.37, 9.26]10% [0%, 19%]24%38%-0.27-0.282026-08-10 → 2026-08-30
tmin00Zbilinear30d21 1 QC3.85 [3.21, 4.40]3.56+0.81 [-1.33, 3.37]4.60 [3.84, 5.18]10% [0%, 17%]29%38%-0.40-0.282026-08-10 → 2026-08-30
tmin00Zbilinear90d21 1 QC3.85 [3.16, 4.40]3.56+0.81 [-1.38, 3.53]4.60 [3.75, 5.18]10% [0%, 17%]29%38%-0.40-0.282026-08-10 → 2026-08-30
tmin00Zbilinear365d21 1 QC3.85 [3.12, 4.45]3.56+0.81 [-1.45, 3.64]4.60 [3.73, 5.20]10% [0%, 17%]29%38%-0.40-0.282026-08-10 → 2026-08-30
tmin00Zbilinearall21 1 QC3.85 [3.07, 4.48]3.56+0.81 [-1.54, 3.63]4.60 [3.66, 5.17]10% [0%, 17%]29%38%-0.40-0.282026-08-10 → 2026-08-30
tmin00Znearest30d21 1 QC4.69 [4.09, 5.39]3.84+2.11 [-0.25, 4.92]5.28 [4.65, 5.90]5% [0%, 14%]14%33%-0.70-0.382026-08-10 → 2026-08-30
tmin00Znearest90d21 1 QC4.69 [4.03, 5.53]3.84+2.11 [-0.35, 5.08]5.28 [4.56, 6.01]5% [0%, 15%]14%33%-0.70-0.382026-08-10 → 2026-08-30
tmin00Znearest365d21 1 QC4.69 [4.02, 5.59]3.84+2.11 [-0.44, 5.23]5.28 [4.57, 6.13]5% [0%, 14%]14%33%-0.70-0.382026-08-10 → 2026-08-30
tmin00Znearestall21 1 QC4.69 [4.07, 5.52]3.84+2.11 [-0.46, 5.24]5.28 [4.54, 6.00]5% [0%, 15%]14%33%-0.70-0.382026-08-10 → 2026-08-30
tmin12Zbilinear30d21 1 QC2.96 [2.19, 3.59]2.63+1.60 [-0.31, 3.04]3.80 [2.57, 4.75]24% [15%, 33%]43%62%-0.07+0.052026-08-10 → 2026-08-30
tmin12Zbilinear90d21 1 QC2.96 [2.10, 3.57]2.63+1.60 [-0.71, 3.00]3.80 [2.39, 4.74]24% [14%, 33%]43%62%-0.07+0.052026-08-10 → 2026-08-30
tmin12Zbilinear365d21 1 QC2.96 [2.02, 3.64]2.63+1.60 [-0.66, 3.11]3.80 [2.34, 4.87]24% [14%, 33%]43%62%-0.07+0.052026-08-10 → 2026-08-30
tmin12Zbilinearall21 1 QC2.96 [2.09, 3.59]2.63+1.60 [-0.66, 3.15]3.80 [2.37, 4.79]24% [14%, 33%]43%62%-0.07+0.052026-08-10 → 2026-08-30
tmin12Znearest30d21 1 QC3.91 [2.75, 4.82]2.91+2.96 [0.79, 4.56]4.82 [3.27, 5.92]14% [0%, 36%]29%48%-0.42-0.052026-08-10 → 2026-08-30
tmin12Znearest90d21 1 QC3.91 [2.48, 4.79]2.91+2.96 [0.28, 4.51]4.82 [2.98, 5.92]14% [0%, 43%]29%48%-0.42-0.052026-08-10 → 2026-08-30
tmin12Znearest365d21 1 QC3.91 [2.54, 4.85]2.91+2.96 [0.36, 4.63]4.82 [3.12, 6.02]14% [0%, 44%]29%48%-0.42-0.052026-08-10 → 2026-08-30
tmin12Znearestall21 1 QC3.91 [2.54, 4.82]2.91+2.96 [0.36, 4.66]4.82 [3.17, 5.84]14% [0%, 42%]29%48%-0.42-0.052026-08-10 → 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 9, 00Z bilinear tmax+20+100-10-202026-08-10: +0.85 °F2026-08-11: +0.61 °F2026-08-12: -9.64 °F2026-08-13: -9.05 °F2026-08-14: -10.41 °F2026-08-15: -1.35 °F2026-08-16: -8.05 °F2026-08-17: -8.2 °F2026-08-18: +0.19 °F2026-08-19: -10.14 °F2026-08-20: +2.07 °F2026-08-21: +7.93 °F2026-08-22: +3.77 °F2026-08-23: +3.31 °F2026-08-24: -2.94 °F2026-08-25: +1.42 °F2026-08-26: +4.13 °F2026-08-27: -0.36 °F2026-08-28: -8.16 °F2026-08-29: +6.85 °F2026-08-30: +4.89 °F2026-08-102026-08-30°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 (21 days, newest first) · download CSV
Climatological dayError °F
2026-08-30+4.89
2026-08-29+6.85
2026-08-28-8.16
2026-08-27-0.36
2026-08-26+4.13
2026-08-25+1.42
2026-08-24-2.94
2026-08-23+3.31
2026-08-22+3.77
2026-08-21+7.93
2026-08-20+2.07
2026-08-19-10.14
2026-08-18+0.19
2026-08-17-8.20
2026-08-16-8.05
2026-08-15-1.35
2026-08-14-10.41
2026-08-13-9.05
2026-08-12-9.64
2026-08-11+0.61
2026-08-10+0.85

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KATL, lead day 9-20 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: 2 days-10 to -8 °F: 5 days-8 to -6 °F: 0 days-6 to -4 °F: 0 days-4 to -2 °F: 1 day-2 to 0 °F: 2 days0 to 2 °F: 4 days2 to 4 °F: 3 days4 to 6 °F: 2 days6 to 8 °F: 2 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| 4.13 · P90 |e| 9.64 °F-200+20 °Fn = 21 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
-12.00-10.002
-10.00-8.005
-8.00-6.000
-6.00-4.000
-4.00-2.001
-2.00+0.002
+0.00+2.004
+2.00+4.003
+4.00+6.002
+6.00+8.002
+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
2026-08214.97 -1.54

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-10 → 2026-08-30 21
NCEP GFS2026-08-10 → 2026-08-30 21
NCEP GFS2026-08-10 → 2026-08-30 21
NCEP GFS2026-08-10 → 2026-08-30 21

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 21 -0.83 [-3.01, 1.15] no
GraphCast (IFS init) 21 -1.05 [-3.44, 0.52] no
ECMWF IFS HRES 16 +1.04 [-1.86, 2.83] no
Persistence (baseline) 21 +0.63 [-1.14, 2.05] no

Cite this page

ShortCastCheck, KATL gfs lead 9, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KATL/model/gfs/lead/9/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KATL (Atlanta Hartsfield), model gfs, lead day 9. 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/9/

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