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

Trenton Mercer · ECMWF AIFS Single · lead day 9

KTTN · aifs_single · 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, 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
tmax00Zbilinear30d21 1 QC3.91 [2.80, 4.96]3.29-1.70 [-4.01, 0.51]4.73 [3.18, 5.94]0% [0%, 0%]33%43%-0.01-0.322026-08-10 → 2026-08-30
tmax00Zbilinear90d21 1 QC3.91 [2.59, 5.05]3.29-1.70 [-4.12, 0.67]4.73 [3.02, 5.96]0% [0%, 0%]33%43%-0.01-0.322026-08-10 → 2026-08-30
tmax00Zbilinear365d21 1 QC3.91 [2.60, 5.21]3.29-1.70 [-4.40, 0.79]4.73 [2.91, 6.16]0% [0%, 0%]33%43%-0.01-0.322026-08-10 → 2026-08-30
tmax00Zbilinearall21 1 QC3.91 [2.72, 5.11]3.29-1.70 [-4.45, 1.00]4.73 [3.11, 6.12]0% [0%, 0%]33%43%-0.01-0.322026-08-10 → 2026-08-30
tmax00Znearest30d21 1 QC3.76 [2.69, 4.72]3.26-1.42 [-3.69, 0.76]4.61 [3.15, 5.74]5% [0%, 14%]33%43%+0.02-0.302026-08-10 → 2026-08-30
tmax00Znearest90d21 1 QC3.76 [2.47, 4.85]3.26-1.42 [-3.80, 0.94]4.61 [2.96, 5.78]5% [0%, 15%]33%43%+0.02-0.302026-08-10 → 2026-08-30
tmax00Znearest365d21 1 QC3.76 [2.47, 4.97]3.26-1.42 [-4.12, 1.07]4.61 [2.82, 5.94]5% [0%, 14%]33%43%+0.02-0.302026-08-10 → 2026-08-30
tmax00Znearestall21 1 QC3.76 [2.60, 4.87]3.26-1.42 [-4.17, 1.29]4.61 [3.05, 5.90]5% [0%, 15%]33%43%+0.02-0.302026-08-10 → 2026-08-30
tmax12Zbilinear30d21 1 QC2.86 [1.85, 4.15]2.68-1.59 [-3.57, -0.17]3.98 [2.30, 5.33]29% [11%, 45%]48%62%+0.26-0.072026-08-10 → 2026-08-30
tmax12Zbilinear90d21 1 QC2.86 [1.69, 4.35]2.68-1.59 [-4.06, 0.04]3.98 [2.11, 5.31]29% [6%, 50%]48%62%+0.26-0.072026-08-10 → 2026-08-30
tmax12Zbilinear365d21 1 QC2.86 [1.69, 4.35]2.68-1.59 [-4.17, 0.19]3.98 [2.11, 5.34]29% [0%, 50%]48%62%+0.26-0.072026-08-10 → 2026-08-30
tmax12Zbilinearall21 1 QC2.86 [1.69, 4.45]2.68-1.59 [-4.36, -0.01]3.98 [2.14, 5.55]29% [0%, 50%]48%62%+0.26-0.072026-08-10 → 2026-08-30
tmax12Znearest30d21 1 QC2.77 [1.76, 4.02]2.72-1.33 [-3.33, 0.12]3.94 [2.28, 5.27]29% [11%, 45%]52%62%+0.28-0.092026-08-10 → 2026-08-30
tmax12Znearest90d21 1 QC2.77 [1.59, 4.18]2.72-1.33 [-3.86, 0.35]3.94 [2.13, 5.25]29% [6%, 50%]52%62%+0.28-0.092026-08-10 → 2026-08-30
tmax12Znearest365d21 1 QC2.77 [1.59, 4.18]2.72-1.33 [-3.97, 0.48]3.94 [2.11, 5.30]29% [0%, 50%]52%62%+0.28-0.092026-08-10 → 2026-08-30
tmax12Znearestall21 1 QC2.77 [1.57, 4.37]2.72-1.33 [-4.18, 0.27]3.94 [2.08, 5.45]29% [0%, 50%]52%62%+0.28-0.092026-08-10 → 2026-08-30
tmin00Zbilinear30d21 1 QC4.31 [2.82, 5.83]3.74+3.89 [2.34, 5.59]5.82 [3.86, 7.36]24% [12%, 38%]43%52%+0.07-0.102026-08-10 → 2026-08-30
tmin00Zbilinear90d21 1 QC4.31 [2.79, 6.06]3.74+3.89 [2.33, 5.72]5.82 [3.84, 7.52]24% [11%, 38%]43%52%+0.07-0.102026-08-10 → 2026-08-30
tmin00Zbilinear365d21 1 QC4.31 [2.67, 6.08]3.74+3.89 [2.26, 5.82]5.82 [3.57, 7.60]24% [11%, 38%]43%52%+0.07-0.102026-08-10 → 2026-08-30
tmin00Zbilinearall21 1 QC4.31 [2.66, 6.23]3.74+3.89 [2.18, 6.10]5.82 [3.52, 7.78]24% [12%, 40%]43%52%+0.07-0.102026-08-10 → 2026-08-30
tmin00Znearest30d21 1 QC4.45 [2.96, 5.99]3.74+4.13 [2.58, 5.83]5.97 [4.01, 7.53]29% [12%, 46%]43%48%+0.04-0.102026-08-10 → 2026-08-30
tmin00Znearest90d21 1 QC4.45 [2.96, 6.18]3.74+4.13 [2.57, 5.95]5.97 [4.00, 7.68]29% [11%, 50%]43%48%+0.04-0.102026-08-10 → 2026-08-30
tmin00Znearest365d21 1 QC4.45 [2.81, 6.23]3.74+4.13 [2.50, 6.05]5.97 [3.74, 7.76]29% [11%, 50%]43%48%+0.04-0.102026-08-10 → 2026-08-30
tmin00Znearestall21 1 QC4.45 [2.81, 6.38]3.74+4.13 [2.42, 6.31]5.97 [3.68, 7.96]29% [14%, 50%]43%48%+0.04-0.102026-08-10 → 2026-08-30
tmin12Zbilinear30d21 1 QC4.05 [2.34, 5.61]2.90+3.84 [2.19, 5.55]5.16 [3.12, 6.56]19% [7%, 36%]38%43%+0.12+0.142026-08-10 → 2026-08-30
tmin12Zbilinear90d21 1 QC4.05 [2.04, 5.86]2.90+3.84 [1.87, 5.86]5.16 [2.80, 6.70]19% [7%, 40%]38%43%+0.12+0.142026-08-10 → 2026-08-30
tmin12Zbilinear365d21 1 QC4.05 [1.81, 5.80]2.90+3.84 [1.80, 5.80]5.16 [2.24, 6.71]19% [3%, 38%]38%43%+0.12+0.142026-08-10 → 2026-08-30
tmin12Zbilinearall21 1 QC4.05 [1.75, 5.64]2.90+3.84 [1.72, 5.64]5.16 [2.15, 6.58]19% [7%, 40%]38%43%+0.12+0.142026-08-10 → 2026-08-30
tmin12Znearest30d21 1 QC4.27 [2.59, 5.88]2.91+4.10 [2.43, 5.85]5.36 [3.31, 6.79]19% [7%, 36%]33%43%+0.07+0.142026-08-10 → 2026-08-30
tmin12Znearest90d21 1 QC4.27 [2.26, 6.14]2.91+4.10 [2.10, 6.14]5.36 [2.98, 6.95]19% [7%, 40%]33%43%+0.07+0.142026-08-10 → 2026-08-30
tmin12Znearest365d21 1 QC4.27 [2.05, 6.09]2.91+4.10 [2.05, 6.09]5.36 [2.42, 6.97]19% [3%, 38%]33%43%+0.07+0.142026-08-10 → 2026-08-30
tmin12Znearestall21 1 QC4.27 [1.98, 5.95]2.91+4.10 [1.96, 5.95]5.36 [2.33, 6.81]19% [7%, 40%]33%43%+0.07+0.142026-08-10 → 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 ECMWF AIFS Single at KTTN, lead day 9, 00Z bilinear tmax+20+100-10-202026-08-10: +1.74 °F2026-08-11: -1.2 °F2026-08-12: -2.63 °F2026-08-13: -1.98 °F2026-08-14: -3.94 °F2026-08-15: -8.47 °F2026-08-16: -4.67 °F2026-08-17: -12.02 °F2026-08-18: -3.51 °F2026-08-19: -1.9 °F2026-08-20: +3.16 °F2026-08-21: +5.21 °F2026-08-22: -4.68 °F2026-08-23: +1.26 °F2026-08-24: +7.42 °F2026-08-25: -1.61 °F2026-08-26: -2.12 °F2026-08-27: -1.12 °F2026-08-28: -4.69 °F2026-08-29: +4.44 °F2026-08-30: -4.34 °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
2026-08-30-4.34
2026-08-29+4.44
2026-08-28-4.69
2026-08-27-1.12
2026-08-26-2.12
2026-08-25-1.61
2026-08-24+7.42
2026-08-23+1.26
2026-08-22-4.68
2026-08-21+5.21
2026-08-20+3.16
2026-08-19-1.90
2026-08-18-3.51
2026-08-17-12.02
2026-08-16-4.67
2026-08-15-8.47
2026-08-14-3.94
2026-08-13-1.98
2026-08-12-2.63
2026-08-11-1.20
2026-08-10+1.74

Error distribution

Distribution of the signed daily error in °F for ECMWF AIFS Single at KTTN, 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: 1 day-12 to -10 °F: 0 days-10 to -8 °F: 1 day-8 to -6 °F: 0 days-6 to -4 °F: 4 days-4 to -2 °F: 4 days-2 to 0 °F: 5 days0 to 2 °F: 2 days2 to 4 °F: 1 day4 to 6 °F: 2 days6 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| 3.51 · P90 |e| 7.42 °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
-14.00-12.001
-12.00-10.000
-10.00-8.001
-8.00-6.000
-6.00-4.004
-4.00-2.004
-2.00+0.005
+0.00+2.002
+2.00+4.001
+4.00+6.002
+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
2026-08213.91 -1.70

Availability

ModelScored period DaysCoverage
ECMWF AIFS Single2026-08-10 → 2026-08-30 21
ECMWF AIFS Single2026-08-10 → 2026-08-30 21
ECMWF AIFS Single2026-08-10 → 2026-08-30 21
ECMWF AIFS Single2026-08-10 → 2026-08-30 21

Compared with other models

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

Other modelCommon days MAE difference °FDistinguishable
NCEP GFS 21 -1.42 [-3.67, 0.96] no
GraphCast (IFS init) 21 -0.24 [-1.47, 0.89] no
ECMWF IFS HRES 16 -0.52 [-5.58, 2.18] no
Persistence (baseline) 21 +0.05 [-0.53, 0.91] no

Cite this page

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

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KTTN (Trenton Mercer), model aifs_single, 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/KTTN/model/aifs_single/lead/9/

Accessed2026-08-31 (data through 2026-08-30; page built 2026-08-31T03:52:06+00:00)

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