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

San Antonio Intl · NCEP GFS · lead day 8

KSAT · 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 QC1.98 [1.08, 2.98]1.88-0.70 [-2.19, 0.88]2.70 [1.20, 3.78]36% [14%, 59%]73%77%+0.09+0.042026-08-09 → 2026-08-30
tmax00Zbilinear90d22 1 QC1.98 [1.04, 3.10]1.88-0.70 [-2.30, 1.33]2.70 [1.16, 3.80]36% [14%, 59%]73%77%+0.09+0.042026-08-09 → 2026-08-30
tmax00Zbilinear365d22 1 QC1.98 [0.97, 3.20]1.88-0.70 [-2.44, 1.30]2.70 [1.10, 3.96]36% [12%, 61%]73%77%+0.09+0.042026-08-09 → 2026-08-30
tmax00Zbilinearall22 1 QC1.98 [1.00, 3.23]1.88-0.70 [-2.63, 1.60]2.70 [1.14, 4.11]36% [11%, 60%]73%77%+0.09+0.042026-08-09 → 2026-08-30
tmax00Znearest30d22 1 QC2.00 [1.02, 3.03]1.93-0.52 [-2.07, 1.13]2.74 [1.20, 3.78]36% [6%, 63%]73%77%+0.08+0.012026-08-09 → 2026-08-30
tmax00Znearest90d22 1 QC2.00 [0.99, 3.19]1.93-0.52 [-2.17, 1.50]2.74 [1.14, 3.85]36% [0%, 64%]73%77%+0.08+0.012026-08-09 → 2026-08-30
tmax00Znearest365d22 1 QC2.00 [0.96, 3.22]1.93-0.52 [-2.34, 1.53]2.74 [1.14, 3.99]36% [0%, 67%]73%77%+0.08+0.012026-08-09 → 2026-08-30
tmax00Znearestall22 1 QC2.00 [0.98, 3.36]1.93-0.52 [-2.60, 1.75]2.74 [1.14, 4.08]36% [0%, 65%]73%77%+0.08+0.012026-08-09 → 2026-08-30
tmax12Zbilinear30d22 1 QC1.76 [0.92, 2.81]1.75-0.23 [-1.15, 1.28]2.49 [1.23, 3.56]50% [33%, 70%]59%77%+0.19+0.112026-08-09 → 2026-08-30
tmax12Zbilinear90d22 1 QC1.76 [0.86, 2.91]1.75-0.23 [-1.20, 1.77]2.49 [1.17, 3.65]50% [31%, 75%]59%77%+0.19+0.112026-08-09 → 2026-08-30
tmax12Zbilinear365d22 1 QC1.76 [0.78, 3.05]1.75-0.23 [-1.20, 1.80]2.49 [1.09, 3.70]50% [29%, 75%]59%77%+0.19+0.112026-08-09 → 2026-08-30
tmax12Zbilinearall22 1 QC1.76 [0.82, 3.08]1.75-0.23 [-1.24, 1.93]2.49 [1.12, 3.75]50% [29%, 75%]59%77%+0.19+0.112026-08-09 → 2026-08-30
tmax12Znearest30d22 1 QC1.82 [0.94, 2.94]1.82+0.06 [-0.90, 1.61]2.47 [1.20, 3.56]41% [22%, 58%]64%73%+0.17+0.072026-08-09 → 2026-08-30
tmax12Znearest90d22 1 QC1.82 [0.87, 3.11]1.82+0.06 [-0.96, 2.20]2.47 [1.11, 3.65]41% [20%, 59%]64%73%+0.17+0.072026-08-09 → 2026-08-30
tmax12Znearest365d22 1 QC1.82 [0.82, 3.18]1.82+0.06 [-0.96, 2.31]2.47 [1.06, 3.70]41% [17%, 60%]64%73%+0.17+0.072026-08-09 → 2026-08-30
tmax12Znearestall22 1 QC1.82 [0.86, 3.21]1.82+0.06 [-0.97, 2.37]2.47 [1.09, 3.70]41% [17%, 59%]64%73%+0.17+0.072026-08-09 → 2026-08-30
tmin00Zbilinear30d22 1 QC1.73 [1.28, 2.30]1.55-1.01 [-2.18, 0.12]1.99 [1.49, 2.49]27% [8%, 40%]59%95%+0.03+0.162026-08-09 → 2026-08-30
tmin00Zbilinear90d22 1 QC1.73 [1.23, 2.55]1.55-1.01 [-2.53, 0.25]1.99 [1.42, 2.60]27% [0%, 43%]59%95%+0.03+0.162026-08-09 → 2026-08-30
tmin00Zbilinear365d22 1 QC1.73 [1.19, 2.55]1.55-1.01 [-2.46, 0.31]1.99 [1.39, 2.62]27% [0%, 43%]59%95%+0.03+0.162026-08-09 → 2026-08-30
tmin00Zbilinearall22 1 QC1.73 [1.18, 2.50]1.55-1.01 [-2.49, 0.30]1.99 [1.39, 2.63]27% [0%, 43%]59%95%+0.03+0.162026-08-09 → 2026-08-30
tmin00Znearest30d22 1 QC1.69 [1.38, 2.08]1.62-0.56 [-1.76, 0.60]1.86 [1.55, 2.21]23% [7%, 33%]59%95%+0.04+0.122026-08-09 → 2026-08-30
tmin00Znearest90d22 1 QC1.69 [1.38, 2.20]1.62-0.56 [-2.11, 0.75]1.86 [1.54, 2.29]23% [0%, 33%]59%95%+0.04+0.122026-08-09 → 2026-08-30
tmin00Znearest365d22 1 QC1.69 [1.37, 2.22]1.62-0.56 [-2.06, 0.79]1.86 [1.54, 2.30]23% [0%, 34%]59%95%+0.04+0.122026-08-09 → 2026-08-30
tmin00Znearestall22 1 QC1.69 [1.38, 2.20]1.62-0.56 [-2.09, 0.78]1.86 [1.51, 2.30]23% [0%, 33%]59%95%+0.04+0.122026-08-09 → 2026-08-30
tmin12Zbilinear30d22 1 QC2.13 [1.72, 2.45]1.73-0.87 [-2.37, 0.69]2.34 [1.87, 2.63]5% [0%, 12%]55%82%-0.20+0.062026-08-09 → 2026-08-30
tmin12Zbilinear90d22 1 QC2.13 [1.61, 2.45]1.73-0.87 [-2.43, 0.86]2.34 [1.73, 2.61]5% [0%, 13%]55%82%-0.20+0.062026-08-09 → 2026-08-30
tmin12Zbilinear365d22 1 QC2.13 [1.63, 2.46]1.73-0.87 [-2.43, 0.90]2.34 [1.78, 2.61]5% [0%, 14%]55%82%-0.20+0.062026-08-09 → 2026-08-30
tmin12Zbilinearall22 1 QC2.13 [1.62, 2.44]1.73-0.87 [-2.43, 0.88]2.34 [1.71, 2.61]5% [0%, 14%]55%82%-0.20+0.062026-08-09 → 2026-08-30
tmin12Znearest30d22 1 QC1.93 [1.50, 2.28]1.72-0.47 [-1.97, 1.08]2.23 [1.69, 2.67]23% [0%, 41%]59%86%-0.09+0.062026-08-09 → 2026-08-30
tmin12Znearest90d22 1 QC1.93 [1.42, 2.30]1.72-0.47 [-2.05, 1.26]2.23 [1.60, 2.68]23% [0%, 43%]59%86%-0.09+0.062026-08-09 → 2026-08-30
tmin12Znearest365d22 1 QC1.93 [1.40, 2.31]1.72-0.47 [-2.04, 1.28]2.23 [1.57, 2.71]23% [0%, 43%]59%86%-0.09+0.062026-08-09 → 2026-08-30
tmin12Znearestall22 1 QC1.93 [1.47, 2.30]1.72-0.47 [-2.03, 1.28]2.23 [1.64, 2.72]23% [0%, 43%]59%86%-0.09+0.062026-08-09 → 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 KSAT, lead day 8, 00Z bilinear tmax+10+50-5-102026-08-09: -0.7 °F2026-08-10: +1.06 °F2026-08-11: -1.88 °F2026-08-12: -1.27 °F2026-08-13: -0.97 °F2026-08-14: -0.59 °F2026-08-15: +1.34 °F2026-08-16: +1.98 °F2026-08-17: +0.43 °F2026-08-18: -0.68 °F2026-08-19: -0.54 °F2026-08-20: +0.18 °F2026-08-21: -2.05 °F2026-08-22: -7.04 °F2026-08-23: -4.72 °F2026-08-24: -6.44 °F2026-08-25: -1.65 °F2026-08-26: +1.65 °F2026-08-27: -1.01 °F2026-08-28: +0.97 °F2026-08-29: +3.37 °F2026-08-30: +3.1 °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+3.10
2026-08-29+3.37
2026-08-28+0.97
2026-08-27-1.01
2026-08-26+1.65
2026-08-25-1.65
2026-08-24-6.44
2026-08-23-4.72
2026-08-22-7.04
2026-08-21-2.05
2026-08-20+0.18
2026-08-19-0.54
2026-08-18-0.68
2026-08-17+0.43
2026-08-16+1.98
2026-08-15+1.34
2026-08-14-0.59
2026-08-13-0.97
2026-08-12-1.27
2026-08-11-1.88
2026-08-10+1.06
2026-08-09-0.70

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KSAT, lead day 8-10 to -9 °F: 0 days-9 to -8 °F: 0 days-8 to -7 °F: 1 day-7 to -6 °F: 1 day-6 to -5 °F: 0 days-5 to -4 °F: 1 day-4 to -3 °F: 0 days-3 to -2 °F: 1 day-2 to -1 °F: 4 days-1 to 0 °F: 5 days0 to 1 °F: 3 days1 to 2 °F: 4 days2 to 3 °F: 0 days3 to 4 °F: 2 days4 to 5 °F: 0 days5 to 6 °F: 0 days6 to 7 °F: 0 days7 to 8 °F: 0 days8 to 9 °F: 0 days9 to 10 °F: 0 daysdashed: P50 |e| 1.3 · P90 |e| 4.58 °F-100+10 °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
-10.00-9.000
-9.00-8.000
-8.00-7.001
-7.00-6.001
-6.00-5.000
-5.00-4.001
-4.00-3.000
-3.00-2.001
-2.00-1.004
-1.00+0.005
+0.00+1.003
+1.00+2.004
+2.00+3.000
+3.00+4.002
+4.00+5.000
+5.00+6.000
+6.00+7.000
+7.00+8.000
+8.00+9.000
+9.00+10.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08221.98 -0.70

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 -0.75 [-1.62, 0.71] no
GraphCast (IFS init) 22 -3.91 [-4.95, -2.24] yes
ECMWF IFS HRES 17 -0.79 [-1.91, 0.27] no
Persistence (baseline) 22 -0.20 [-1.17, 0.82] no

Cite this page

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

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KSAT (San Antonio Intl), 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/KSAT/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