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

Atlanta Hartsfield · NCEP GFS · lead day 8

KATL · gfs · lead 8

Target day = initialization date + 8 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
tmax00Zbilinear30d22 1 QC3.71 [2.56, 4.55]3.75-0.27 [-1.83, 1.86]4.64 [3.35, 5.34]23% [3%, 47%]27%45%+0.11+0.102026-08-09 → 2026-08-30
tmax00Zbilinear90d22 1 QC3.71 [2.23, 4.64]3.75-0.27 [-2.02, 2.23]4.64 [2.70, 5.40]23% [0%, 51%]27%45%+0.11+0.102026-08-09 → 2026-08-30
tmax00Zbilinear365d22 1 QC3.71 [2.16, 4.68]3.75-0.27 [-2.04, 2.33]4.64 [2.61, 5.37]23% [0%, 53%]27%45%+0.11+0.102026-08-09 → 2026-08-30
tmax00Zbilinearall22 1 QC3.71 [2.27, 4.64]3.75-0.27 [-1.98, 2.12]4.64 [2.91, 5.32]23% [0%, 55%]27%45%+0.11+0.102026-08-09 → 2026-08-30
tmax00Znearest30d22 1 QC3.83 [2.87, 4.65]3.76+0.40 [-1.18, 2.56]4.61 [3.38, 5.41]14% [0%, 26%]23%45%+0.08+0.102026-08-09 → 2026-08-30
tmax00Znearest90d22 1 QC3.83 [2.69, 4.71]3.76+0.40 [-1.32, 2.94]4.61 [3.00, 5.47]14% [0%, 27%]23%45%+0.08+0.102026-08-09 → 2026-08-30
tmax00Znearest365d22 1 QC3.83 [2.57, 4.81]3.76+0.40 [-1.26, 3.06]4.61 [2.94, 5.58]14% [0%, 27%]23%45%+0.08+0.102026-08-09 → 2026-08-30
tmax00Znearestall22 1 QC3.83 [2.57, 4.64]3.76+0.40 [-1.25, 2.76]4.61 [2.95, 5.42]14% [0%, 29%]23%45%+0.08+0.102026-08-09 → 2026-08-30
tmax12Zbilinear30d22 1 QC4.43 [2.65, 7.12]4.74-2.04 [-5.43, 0.42]6.20 [3.45, 9.30]14% [0%, 27%]41%50%-0.06-0.132026-08-09 → 2026-08-30
tmax12Zbilinear90d22 1 QC4.43 [2.51, 8.25]4.74-2.04 [-6.64, 0.55]6.20 [3.17, 10.48]14% [0%, 29%]41%50%-0.06-0.132026-08-09 → 2026-08-30
tmax12Zbilinear365d22 1 QC4.43 [2.46, 7.91]4.74-2.04 [-6.85, 0.60]6.20 [3.08, 9.82]14% [0%, 29%]41%50%-0.06-0.132026-08-09 → 2026-08-30
tmax12Zbilinearall22 1 QC4.43 [2.45, 7.89]4.74-2.04 [-6.24, 0.72]6.20 [2.98, 9.84]14% [0%, 29%]41%50%-0.06-0.132026-08-09 → 2026-08-30
tmax12Znearest30d22 1 QC4.35 [2.38, 7.12]4.63-1.73 [-5.15, 0.81]6.08 [2.96, 9.16]14% [0%, 27%]32%50%-0.04-0.112026-08-09 → 2026-08-30
tmax12Znearest90d22 1 QC4.35 [2.23, 8.32]4.63-1.73 [-6.26, 1.11]6.08 [2.74, 10.03]14% [0%, 29%]32%50%-0.04-0.112026-08-09 → 2026-08-30
tmax12Znearest365d22 1 QC4.35 [2.17, 8.04]4.63-1.73 [-6.61, 1.11]6.08 [2.55, 9.84]14% [0%, 29%]32%50%-0.04-0.112026-08-09 → 2026-08-30
tmax12Znearestall22 1 QC4.35 [2.12, 8.13]4.63-1.73 [-5.98, 1.19]6.08 [2.66, 9.81]14% [0%, 29%]32%50%-0.04-0.112026-08-09 → 2026-08-30
tmin00Zbilinear30d22 1 QC3.24 [2.31, 4.17]2.83+1.48 [-0.17, 3.31]3.68 [2.59, 4.53]5% [0%, 12%]27%55%-0.27-0.102026-08-09 → 2026-08-30
tmin00Zbilinear90d22 1 QC3.24 [2.23, 4.32]2.83+1.48 [-0.37, 3.54]3.68 [2.48, 4.66]5% [0%, 13%]27%55%-0.27-0.102026-08-09 → 2026-08-30
tmin00Zbilinear365d22 1 QC3.24 [2.20, 4.34]2.83+1.48 [-0.36, 3.72]3.68 [2.46, 4.66]5% [0%, 14%]27%55%-0.27-0.102026-08-09 → 2026-08-30
tmin00Zbilinearall22 1 QC3.24 [2.17, 4.29]2.83+1.48 [-0.38, 3.50]3.68 [2.44, 4.61]5% [0%, 14%]27%55%-0.27-0.102026-08-09 → 2026-08-30
tmin00Znearest30d22 1 QC3.92 [2.84, 5.33]3.17+2.73 [0.93, 4.88]4.64 [3.22, 5.96]18% [8%, 28%]18%41%-0.54-0.232026-08-09 → 2026-08-30
tmin00Znearest90d22 1 QC3.92 [2.71, 5.47]3.17+2.73 [0.68, 5.19]4.64 [3.13, 6.12]18% [8%, 29%]18%41%-0.54-0.232026-08-09 → 2026-08-30
tmin00Znearest365d22 1 QC3.92 [2.79, 5.51]3.17+2.73 [0.70, 5.32]4.64 [3.16, 6.16]18% [4%, 29%]18%41%-0.54-0.232026-08-09 → 2026-08-30
tmin00Znearestall22 1 QC3.92 [2.77, 5.31]3.17+2.73 [0.63, 5.20]4.64 [3.15, 6.12]18% [0%, 29%]18%41%-0.54-0.232026-08-09 → 2026-08-30
tmin12Zbilinear30d22 1 QC2.46 [1.40, 3.47]2.34+1.16 [-0.13, 2.35]3.20 [1.77, 4.21]27% [9%, 53%]50%77%+0.04+0.092026-08-09 → 2026-08-30
tmin12Zbilinear90d22 1 QC2.46 [1.23, 3.58]2.34+1.16 [-0.26, 2.38]3.20 [1.54, 4.28]27% [7%, 58%]50%77%+0.04+0.092026-08-09 → 2026-08-30
tmin12Zbilinear365d22 1 QC2.46 [1.26, 3.59]2.34+1.16 [-0.29, 2.51]3.20 [1.59, 4.31]27% [6%, 57%]50%77%+0.04+0.092026-08-09 → 2026-08-30
tmin12Zbilinearall22 1 QC2.46 [1.25, 3.52]2.34+1.16 [-0.23, 2.50]3.20 [1.57, 4.19]27% [7%, 57%]50%77%+0.04+0.092026-08-09 → 2026-08-30
tmin12Znearest30d22 1 QC3.05 [1.76, 4.11]2.57+2.37 [1.11, 3.49]3.97 [2.53, 4.90]27% [14%, 50%]41%55%-0.20+0.002026-08-09 → 2026-08-30
tmin12Znearest90d22 1 QC3.05 [1.44, 4.19]2.57+2.37 [0.98, 3.54]3.97 [2.19, 4.99]27% [14%, 56%]41%55%-0.20+0.002026-08-09 → 2026-08-30
tmin12Znearest365d22 1 QC3.05 [1.54, 4.23]2.57+2.37 [1.00, 3.61]3.97 [2.23, 5.08]27% [14%, 55%]41%55%-0.20+0.002026-08-09 → 2026-08-30
tmin12Znearestall22 1 QC3.05 [1.54, 4.15]2.57+2.37 [1.05, 3.60]3.97 [2.21, 4.98]27% [14%, 54%]41%55%-0.20+0.002026-08-09 → 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 8, 00Z bilinear tmax+20+100-10-202026-08-09: +3.58 °F2026-08-10: +0.88 °F2026-08-11: +0.73 °F2026-08-12: -3.33 °F2026-08-13: -0.15 °F2026-08-14: -0.22 °F2026-08-15: -10.99 °F2026-08-16: -2.37 °F2026-08-17: +4.37 °F2026-08-18: +6.04 °F2026-08-19: +3.07 °F2026-08-20: +2.47 °F2026-08-21: +6.57 °F2026-08-22: +4.11 °F2026-08-23: -6.47 °F2026-08-24: -0.89 °F2026-08-25: -8.98 °F2026-08-26: +2.94 °F2026-08-27: -5.38 °F2026-08-28: +2.09 °F2026-08-29: -5 °F2026-08-30: +1.03 °F2026-08-092026-08-30°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 (22 days, newest first) · download CSV
Climatological dayError °F
2026-08-30+1.03
2026-08-29-5.00
2026-08-28+2.09
2026-08-27-5.38
2026-08-26+2.94
2026-08-25-8.98
2026-08-24-0.89
2026-08-23-6.47
2026-08-22+4.11
2026-08-21+6.57
2026-08-20+2.47
2026-08-19+3.07
2026-08-18+6.04
2026-08-17+4.37
2026-08-16-2.37
2026-08-15-10.99
2026-08-14-0.22
2026-08-13-0.15
2026-08-12-3.33
2026-08-11+0.73
2026-08-10+0.88
2026-08-09+3.58

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KATL, lead day 8-20 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: 1 day-6 to -4 °F: 2 days-4 to -2 °F: 2 days-2 to 0 °F: 3 days0 to 2 °F: 3 days2 to 4 °F: 5 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| 3.2 · P90 |e| 6.56 °F-200+20 °Fn = 22 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
-8.00-6.001
-6.00-4.002
-4.00-2.002
-2.00+0.003
+0.00+2.003
+2.00+4.005
+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
2026-08223.71 -0.27

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-09 → 2026-08-30 22
NCEP GFS2026-08-09 → 2026-08-30 22
NCEP GFS2026-08-09 → 2026-08-30 22
NCEP GFS2026-08-09 → 2026-08-30 22

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 22 -1.82 [-6.50, 0.70] no
GraphCast (IFS init) 22 -1.94 [-5.82, 1.02] no
ECMWF IFS HRES 17 +1.87 [0.40, 3.17] yes
Persistence (baseline) 22 -0.47 [-3.14, 1.51] no

Cite this page

ShortCastCheck, KATL gfs lead 8, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KATL/model/gfs/lead/8/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KATL (Atlanta Hartsfield), model gfs, lead day 8. 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/8/

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