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

Trenton Mercer · ECMWF AIFS Single · lead day 4

KTTN · aifs_single · lead 4

Target day = initialization date + 4 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, aifs-single-gpid5, 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
tmax00Zbilinear30d26 1 QC1.76 [1.47, 2.20]1.76+0.05 [-0.76, 0.96]2.27 [1.88, 2.77]38% [24%, 52%]65%77%+0.50+0.492026-08-05 → 2026-08-30
tmax00Zbilinear90d26 1 QC1.76 [1.46, 2.35]1.76+0.05 [-0.94, 1.09]2.27 [1.85, 2.88]38% [22%, 50%]65%77%+0.50+0.492026-08-05 → 2026-08-30
tmax00Zbilinear365d26 1 QC1.76 [1.47, 2.29]1.76+0.05 [-0.97, 1.31]2.27 [1.82, 2.90]38% [23%, 52%]65%77%+0.50+0.492026-08-05 → 2026-08-30
tmax00Zbilinearall26 1 QC1.76 [1.48, 2.31]1.76+0.05 [-0.97, 1.21]2.27 [1.81, 2.86]38% [21%, 52%]65%77%+0.50+0.492026-08-05 → 2026-08-30
tmax00Znearest30d26 1 QC1.83 [1.54, 2.25]1.78+0.34 [-0.47, 1.23]2.33 [1.95, 2.84]42% [29%, 53%]58%73%+0.48+0.492026-08-05 → 2026-08-30
tmax00Znearest90d26 1 QC1.83 [1.55, 2.36]1.78+0.34 [-0.69, 1.36]2.33 [1.92, 2.94]42% [27%, 52%]58%73%+0.48+0.492026-08-05 → 2026-08-30
tmax00Znearest365d26 1 QC1.83 [1.55, 2.33]1.78+0.34 [-0.69, 1.55]2.33 [1.89, 2.93]42% [27%, 53%]58%73%+0.48+0.492026-08-05 → 2026-08-30
tmax00Znearestall26 1 QC1.83 [1.56, 2.31]1.78+0.34 [-0.67, 1.47]2.33 [1.89, 2.92]42% [25%, 53%]58%73%+0.48+0.492026-08-05 → 2026-08-30
tmax12Zbilinear30d26 1 QC1.80 [1.50, 2.17]1.70+0.66 [-0.28, 1.43]2.18 [1.86, 2.49]27% [14%, 39%]54%85%+0.49+0.512026-08-05 → 2026-08-30
tmax12Zbilinear90d26 1 QC1.80 [1.49, 2.26]1.70+0.66 [-0.57, 1.60]2.18 [1.83, 2.58]27% [11%, 38%]54%85%+0.49+0.512026-08-05 → 2026-08-30
tmax12Zbilinear365d26 1 QC1.80 [1.48, 2.30]1.70+0.66 [-0.54, 1.77]2.18 [1.82, 2.59]27% [11%, 38%]54%85%+0.49+0.512026-08-05 → 2026-08-30
tmax12Zbilinearall26 1 QC1.80 [1.50, 2.36]1.70+0.66 [-0.52, 1.74]2.18 [1.80, 2.61]27% [9%, 38%]54%85%+0.49+0.512026-08-05 → 2026-08-30
tmax12Znearest30d26 1 QC1.95 [1.58, 2.36]1.71+0.98 [0.03, 1.75]2.32 [1.94, 2.68]27% [14%, 39%]50%77%+0.45+0.512026-08-05 → 2026-08-30
tmax12Znearest90d26 1 QC1.95 [1.56, 2.42]1.71+0.98 [-0.27, 1.94]2.32 [1.91, 2.73]27% [11%, 38%]50%77%+0.45+0.512026-08-05 → 2026-08-30
tmax12Znearest365d26 1 QC1.95 [1.56, 2.47]1.71+0.98 [-0.29, 2.08]2.32 [1.90, 2.76]27% [11%, 38%]50%77%+0.45+0.512026-08-05 → 2026-08-30
tmax12Znearestall26 1 QC1.95 [1.57, 2.47]1.71+0.98 [-0.25, 2.05]2.32 [1.88, 2.76]27% [9%, 38%]50%77%+0.45+0.512026-08-05 → 2026-08-30
tmin00Zbilinear30d26 1 QC4.15 [3.20, 5.12]2.35+4.11 [3.14, 5.12]4.94 [3.77, 5.87]8% [0%, 20%]15%46%-0.27+0.282026-08-05 → 2026-08-30
tmin00Zbilinear90d26 1 QC4.15 [3.01, 5.28]2.35+4.11 [2.93, 5.28]4.94 [3.59, 6.03]8% [0%, 21%]15%46%-0.27+0.282026-08-05 → 2026-08-30
tmin00Zbilinear365d26 1 QC4.15 [3.08, 5.44]2.35+4.11 [2.96, 5.44]4.94 [3.55, 6.18]8% [0%, 21%]15%46%-0.27+0.282026-08-05 → 2026-08-30
tmin00Zbilinearall26 1 QC4.15 [2.99, 5.42]2.35+4.11 [2.90, 5.42]4.94 [3.59, 6.01]8% [0%, 21%]15%46%-0.27+0.282026-08-05 → 2026-08-30
tmin00Znearest30d26 1 QC4.38 [3.41, 5.36]2.35+4.36 [3.38, 5.36]5.15 [4.01, 6.09]8% [0%, 20%]15%42%-0.34+0.282026-08-05 → 2026-08-30
tmin00Znearest90d26 1 QC4.38 [3.23, 5.54]2.35+4.36 [3.18, 5.54]5.15 [3.81, 6.25]8% [0%, 21%]15%42%-0.34+0.282026-08-05 → 2026-08-30
tmin00Znearest365d26 1 QC4.38 [3.29, 5.69]2.35+4.36 [3.23, 5.69]5.15 [3.78, 6.38]8% [0%, 21%]15%42%-0.34+0.282026-08-05 → 2026-08-30
tmin00Znearestall26 1 QC4.38 [3.20, 5.68]2.35+4.36 [3.16, 5.68]5.15 [3.79, 6.23]8% [0%, 21%]15%42%-0.34+0.282026-08-05 → 2026-08-30
tmin12Zbilinear30d26 1 QC4.01 [3.33, 4.71]2.20+3.93 [3.20, 4.68]4.70 [3.87, 5.47]15% [7%, 24%]19%46%-0.23+0.332026-08-05 → 2026-08-30
tmin12Zbilinear90d26 1 QC4.01 [3.14, 4.97]2.20+3.93 [3.05, 4.95]4.70 [3.69, 5.71]15% [7%, 25%]19%46%-0.23+0.332026-08-05 → 2026-08-30
tmin12Zbilinear365d26 1 QC4.01 [3.17, 5.08]2.20+3.93 [3.05, 5.07]4.70 [3.70, 5.87]15% [7%, 27%]19%46%-0.23+0.332026-08-05 → 2026-08-30
tmin12Zbilinearall26 1 QC4.01 [3.05, 4.90]2.20+3.93 [2.91, 4.85]4.70 [3.60, 5.68]15% [7%, 27%]19%46%-0.23+0.332026-08-05 → 2026-08-30
tmin12Znearest30d26 1 QC4.24 [3.54, 4.94]2.21+4.19 [3.46, 4.94]4.92 [4.13, 5.68]12% [4%, 20%]19%31%-0.30+0.322026-08-05 → 2026-08-30
tmin12Znearest90d26 1 QC4.24 [3.35, 5.19]2.21+4.19 [3.27, 5.19]4.92 [3.93, 5.88]12% [0%, 22%]19%31%-0.30+0.322026-08-05 → 2026-08-30
tmin12Znearest365d26 1 QC4.24 [3.40, 5.30]2.21+4.19 [3.29, 5.30]4.92 [3.97, 6.07]12% [0%, 22%]19%31%-0.30+0.322026-08-05 → 2026-08-30
tmin12Znearestall26 1 QC4.24 [3.26, 5.13]2.21+4.19 [3.18, 5.12]4.92 [3.84, 5.87]12% [0%, 25%]19%31%-0.30+0.322026-08-05 → 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 ECMWF AIFS Single at KTTN, lead day 4, 00Z bilinear tmax+10+50-5-102026-08-05: -3.52 °F2026-08-06: -0.64 °F2026-08-07: -3.41 °F2026-08-08: -1.06 °F2026-08-09: +1.57 °F2026-08-10: +2.03 °F2026-08-11: +2.51 °F2026-08-12: -0.46 °F2026-08-13: +0.5 °F2026-08-14: -1.45 °F2026-08-15: -4.21 °F2026-08-16: -0.18 °F2026-08-17: +3.76 °F2026-08-18: -0.05 °F2026-08-19: -0.03 °F2026-08-20: +1.65 °F2026-08-21: -3.32 °F2026-08-22: -2.11 °F2026-08-23: +0.79 °F2026-08-24: -1.02 °F2026-08-25: +1.76 °F2026-08-26: +0.46 °F2026-08-27: -0.78 °F2026-08-28: +0.94 °F2026-08-29: +5.79 °F2026-08-30: +1.74 °F2026-08-052026-08-30°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 (26 days, newest first) · download CSV
Climatological dayError °F
2026-08-30+1.74
2026-08-29+5.79
2026-08-28+0.94
2026-08-27-0.78
2026-08-26+0.46
2026-08-25+1.76
2026-08-24-1.02
2026-08-23+0.79
2026-08-22-2.11
2026-08-21-3.32
2026-08-20+1.65
2026-08-19-0.03
2026-08-18-0.05
2026-08-17+3.76
2026-08-16-0.18
2026-08-15-4.21
2026-08-14-1.45
2026-08-13+0.50
2026-08-12-0.46
2026-08-11+2.51
2026-08-10+2.03
2026-08-09+1.57
2026-08-08-1.06
2026-08-07-3.41
2026-08-06-0.64
2026-08-05-3.52

Error distribution

Distribution of the signed daily error in °F for ECMWF AIFS Single at KTTN, lead day 4-10 to -9 °F: 0 days-9 to -8 °F: 0 days-8 to -7 °F: 0 days-7 to -6 °F: 0 days-6 to -5 °F: 0 days-5 to -4 °F: 1 day-4 to -3 °F: 3 days-3 to -2 °F: 1 day-2 to -1 °F: 3 days-1 to 0 °F: 6 days0 to 1 °F: 4 days1 to 2 °F: 4 days2 to 3 °F: 2 days3 to 4 °F: 1 day4 to 5 °F: 0 days5 to 6 °F: 1 day6 to 7 °F: 0 days7 to 8 °F: 0 days8 to 9 °F: 0 days9 to 10 °F: 0 daysdashed: P50 |e| 1.51 · P90 |e| 3.64 °F-100+10 °Fn = 26 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
-8.00-7.000
-7.00-6.000
-6.00-5.000
-5.00-4.001
-4.00-3.003
-3.00-2.001
-2.00-1.003
-1.00+0.006
+0.00+1.004
+1.00+2.004
+2.00+3.002
+3.00+4.001
+4.00+5.000
+5.00+6.001
+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
2026-08261.76 +0.05

Availability

ModelScored period DaysCoverage
ECMWF AIFS Single2026-08-05 → 2026-08-30 26
ECMWF AIFS Single2026-08-05 → 2026-08-30 26
ECMWF AIFS Single2026-08-05 → 2026-08-30 26
ECMWF AIFS Single2026-08-05 → 2026-08-30 26

Compared with other models

Paired bootstrap on the days both models cover (90d, 00Z, bilinear, daily maximum). Negative means ECMWF AIFS Single has the lower MAE. "Distinguishable" means the 95 % interval excludes zero.

Other modelCommon days MAE difference °FDistinguishable
NCEP GFS 26 -1.39 [-2.35, -0.26] yes
GraphCast (IFS init) 25 -0.85 [-1.51, -0.17] yes
ECMWF IFS HRES 20 -1.78 [-2.70, -0.55] yes
Persistence (baseline) 26 -1.78 [-2.85, -0.31] yes

Cite this page

ShortCastCheck, KTTN aifs_single lead 4, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KTTN/model/aifs_single/lead/4/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KTTN (Trenton Mercer), model aifs_single, lead day 4. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KTTN/model/aifs_single/lead/4/

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