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

Los Angeles Intl · GraphCast (IFS init) · lead day 8

KLAX · graphcast_ifs · 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, GRAP_v100, starting 2026-01-01 — days before that ran a different version of the model and are excluded rather than silently pooled. Of the scored days, 2 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 2 QC4.90 [2.97, 6.91]2.61-4.90 [-6.91, -2.97]5.74 [3.38, 7.51]5% [0%, 12%]18%36%-0.46+0.172026-08-09 → 2026-08-30
tmax00Zbilinear90d22 2 QC4.90 [2.82, 7.11]2.61-4.90 [-7.11, -2.82]5.74 [3.20, 7.62]5% [0%, 13%]18%36%-0.46+0.172026-08-09 → 2026-08-30
tmax00Zbilinear365d28 2 QC4.78 [3.05, 6.69]2.51-4.76 [-6.69, -3.02]5.60 [3.51, 7.27]7% [0%, 16%]18%36%-0.01+0.402026-01-09 → 2026-08-30
tmax00Zbilinearall28 2 QC4.78 [3.12, 6.68]2.51-4.76 [-6.67, -3.11]5.60 [3.63, 7.29]7% [0%, 16%]18%36%-0.01+0.402026-01-09 → 2026-08-30
tmax00Znearest30d22 2 QC7.57 [5.33, 9.86]2.73-7.57 [-9.86, -5.33]8.20 [5.60, 10.31]0% [0%, 0%]0%0%-1.25+0.132026-08-09 → 2026-08-30
tmax00Znearest90d22 2 QC7.57 [5.13, 10.03]2.73-7.57 [-10.03, -5.13]8.20 [5.35, 10.42]0% [0%, 0%]0%0%-1.25+0.132026-08-09 → 2026-08-30
tmax00Znearest365d28 2 QC6.91 [4.81, 9.19]2.84-6.86 [-9.18, -4.68]7.64 [5.20, 9.76]4% [0%, 13%]4%7%-0.47+0.322026-01-09 → 2026-08-30
tmax00Znearestall28 2 QC6.91 [4.65, 9.44]2.84-6.86 [-9.44, -4.49]7.64 [5.10, 9.89]4% [0%, 14%]4%7%-0.47+0.322026-01-09 → 2026-08-30
tmax12Zbilinear30d22 2 QC4.24 [2.36, 5.94]2.37-4.24 [-5.94, -2.36]5.03 [2.58, 6.56]5% [0%, 19%]23%50%-0.26+0.252026-08-09 → 2026-08-30
tmax12Zbilinear90d22 2 QC4.24 [2.18, 6.13]2.37-4.24 [-6.13, -2.18]5.03 [2.27, 6.69]5% [0%, 22%]23%50%-0.26+0.252026-08-09 → 2026-08-30
tmax12Zbilinear365d27 2 QC4.10 [2.43, 5.84]2.42-3.89 [-5.66, -2.11]4.87 [2.74, 6.41]7% [0%, 22%]22%48%+0.05+0.382026-01-09 → 2026-08-30
tmax12Zbilinearall27 2 QC4.10 [2.52, 5.86]2.42-3.89 [-5.78, -2.12]4.87 [2.95, 6.50]7% [0%, 25%]22%48%+0.05+0.382026-01-09 → 2026-08-30
tmax12Znearest30d22 2 QC7.10 [4.97, 9.08]2.57-7.10 [-9.08, -4.97]7.67 [5.16, 9.48]0% [0%, 0%]0%0%-1.11+0.182026-08-09 → 2026-08-30
tmax12Znearest90d22 2 QC7.10 [4.70, 9.19]2.57-7.10 [-9.19, -4.70]7.67 [4.79, 9.55]0% [0%, 0%]0%0%-1.11+0.182026-08-09 → 2026-08-30
tmax12Znearest365d27 2 QC6.43 [4.16, 8.56]2.83-6.21 [-8.47, -3.46]7.13 [4.48, 9.11]4% [0%, 14%]4%7%-0.48+0.272026-01-09 → 2026-08-30
tmax12Znearestall27 2 QC6.43 [3.99, 8.73]2.83-6.21 [-8.72, -3.29]7.13 [4.45, 9.17]4% [0%, 15%]4%7%-0.48+0.272026-01-09 → 2026-08-30
tmin00Zbilinear30d22 2 QC1.69 [0.97, 2.58]1.65-0.85 [-2.16, 0.40]2.19 [1.27, 3.04]36% [15%, 55%]64%86%+0.27+0.172026-08-09 → 2026-08-30
tmin00Zbilinear90d22 2 QC1.69 [0.96, 2.73]1.65-0.85 [-2.39, 0.52]2.19 [1.22, 3.16]36% [13%, 56%]64%86%+0.27+0.172026-08-09 → 2026-08-30
tmin00Zbilinear365d28 2 QC3.60 [1.17, 7.40]3.97+1.61 [-1.50, 6.88]5.38 [1.46, 8.72]29% [7%, 48%]50%68%+0.05-0.022026-01-09 → 2026-08-30
tmin00Zbilinearall28 2 QC3.60 [1.20, 8.44]3.97+1.61 [-1.69, 7.82]5.38 [1.53, 9.33]29% [4%, 50%]50%68%+0.05-0.022026-01-09 → 2026-08-30
tmin00Znearest30d22 2 QC1.49 [1.04, 2.04]1.48+0.14 [-0.99, 1.18]1.81 [1.34, 2.28]36% [17%, 52%]73%91%+0.36+0.262026-08-09 → 2026-08-30
tmin00Znearest90d22 2 QC1.49 [0.95, 2.11]1.48+0.14 [-1.18, 1.26]1.81 [1.20, 2.33]36% [15%, 53%]73%91%+0.36+0.262026-08-09 → 2026-08-30
tmin00Znearest365d28 2 QC4.18 [1.21, 9.73]4.68+3.11 [-0.43, 9.44]6.73 [1.50, 11.44]29% [7%, 46%]57%71%-0.10-0.202026-01-09 → 2026-08-30
tmin00Znearestall28 2 QC4.18 [1.27, 10.71]4.68+3.11 [-0.60, 10.70]6.73 [1.60, 12.13]29% [3%, 45%]57%71%-0.10-0.202026-01-09 → 2026-08-30
tmin12Zbilinear30d22 2 QC1.35 [0.74, 2.12]1.34-0.50 [-1.61, 0.58]1.78 [0.93, 2.50]45% [20%, 67%]73%86%+0.42+0.322026-08-09 → 2026-08-30
tmin12Zbilinear90d22 2 QC1.35 [0.69, 2.28]1.34-0.50 [-1.75, 0.76]1.78 [0.83, 2.60]45% [17%, 71%]73%86%+0.42+0.322026-08-09 → 2026-08-30
tmin12Zbilinear365d27 2 QC3.11 [0.86, 7.02]3.49+1.60 [-1.03, 6.76]4.96 [1.09, 8.51]37% [8%, 63%]59%70%+0.18+0.112026-01-09 → 2026-08-30
tmin12Zbilinearall27 2 QC3.11 [0.93, 8.15]3.49+1.60 [-1.28, 7.82]4.96 [1.17, 9.18]37% [6%, 60%]59%70%+0.18+0.112026-01-09 → 2026-08-30
tmin12Znearest30d22 2 QC1.32 [0.93, 1.73]1.20+0.52 [-0.41, 1.42]1.59 [1.20, 2.00]45% [28%, 64%]73%95%+0.43+0.402026-08-09 → 2026-08-30
tmin12Znearest90d22 2 QC1.32 [0.84, 1.82]1.20+0.52 [-0.57, 1.55]1.59 [1.05, 2.12]45% [25%, 69%]73%95%+0.43+0.402026-08-09 → 2026-08-30
tmin12Znearest365d27 2 QC3.76 [1.06, 9.43]4.21+3.10 [0.05, 9.24]6.40 [1.35, 11.33]37% [13%, 58%]59%78%+0.02-0.072026-01-09 → 2026-08-30
tmin12Znearestall27 2 QC3.76 [1.13, 10.67]4.21+3.10 [-0.12, 10.67]6.40 [1.39, 12.15]37% [7%, 57%]59%78%+0.02-0.072026-01-09 → 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 GraphCast (IFS init) at KLAX, lead day 8, 00Z bilinear tmax+10+50-5-102026-08-09: -5.65 °F2026-08-10: -2.51 °F2026-08-11: -3.18 °F2026-08-12: -1.5 °F2026-08-13: -2.02 °F2026-08-14: -4.34 °F2026-08-15: -0.81 °F2026-08-16: -2.26 °F2026-08-17: -2.45 °F2026-08-18: -5.54 °F2026-08-19: -7.72 °F2026-08-20: -1.74 °F2026-08-21: -5.39 °F2026-08-22: -6.16 °F2026-08-23: -9.58 °F2026-08-24: -9.94 °F2026-08-25: -8.81 °F2026-08-26: -8.47 °F2026-08-27: -9.8 °F2026-08-28: -3.24 °F2026-08-29: -5.61 °F2026-08-30: -1.12 °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
2026-08-30-1.12
2026-08-29-5.61
2026-08-28-3.24
2026-08-27-9.80
2026-08-26-8.47
2026-08-25-8.81
2026-08-24-9.94
2026-08-23-9.58
2026-08-22-6.16
2026-08-21-5.39
2026-08-20-1.74
2026-08-19-7.72
2026-08-18-5.54
2026-08-17-2.45
2026-08-16-2.26
2026-08-15-0.81
2026-08-14-4.34
2026-08-13-2.02
2026-08-12-1.50
2026-08-11-3.18
2026-08-10-2.51
2026-08-09-5.65

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KLAX, lead day 8-10 to -9 °F: 3 days-9 to -8 °F: 3 days-8 to -7 °F: 1 day-7 to -6 °F: 1 day-6 to -5 °F: 6 days-5 to -4 °F: 2 days-4 to -3 °F: 2 days-3 to -2 °F: 5 days-2 to -1 °F: 3 days-1 to 0 °F: 1 day0 to 1 °F: 1 day1 to 2 °F: 0 days2 to 3 °F: 0 days3 to 4 °F: 0 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| 4.88 · P90 |e| 9.04 °F-100+10 °Fn = 28 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
-10.00-9.003
-9.00-8.003
-8.00-7.001
-7.00-6.001
-6.00-5.006
-5.00-4.002
-4.00-3.002
-3.00-2.005
-2.00-1.003
-1.00+0.001
+0.00+1.001
+1.00+2.000
+2.00+3.000
+3.00+4.000
+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
2026-08224.90 -4.90
2026-0164.36 -4.23

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-09 → 2026-08-30 28
GraphCast (IFS init)2026-01-09 → 2026-08-30 28
GraphCast (IFS init)2026-01-09 → 2026-08-30 27
GraphCast (IFS init)2026-01-09 → 2026-08-30 27

Compared with other models

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

Other modelCommon days MAE difference °FDistinguishable
ECMWF AIFS Single 22 +3.03 [1.45, 4.76] yes
NCEP GFS 22 +1.91 [0.16, 3.89] yes
ECMWF IFS HRES 17 +2.21 [0.52, 3.97] yes
Persistence (baseline) 22 +1.54 [0.41, 2.55] yes

Cite this page

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

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KLAX (Los Angeles Intl), model graphcast_ifs, 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/KLAX/model/graphcast_ifs/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