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

Phoenix Sky Harbor · GraphCast (IFS init) · lead day 5

KPHX · graphcast_ifs · lead 5

Target day = initialization date + 5 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, 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
tmax00Zbilinear30d25 1 QC5.06 [3.46, 6.67]2.56-4.87 [-6.67, -3.01]5.90 [3.81, 7.53]4% [0%, 11%]12%28%+0.07+0.532026-08-06 → 2026-08-30
tmax00Zbilinear90d25 1 QC5.06 [3.28, 6.87]2.56-4.87 [-6.87, -2.88]5.90 [3.65, 7.65]4% [0%, 11%]12%28%+0.07+0.532026-08-06 → 2026-08-30
tmax00Zbilinear365d31 1 QC5.08 [3.63, 6.68]2.52-4.92 [-6.68, -3.24]5.87 [3.99, 7.47]3% [0%, 10%]13%29%+0.12+0.552026-01-06 → 2026-08-30
tmax00Zbilinearall31 1 QC5.08 [3.63, 6.60]2.52-4.92 [-6.60, -3.34]5.87 [4.07, 7.40]3% [0%, 10%]13%29%+0.12+0.552026-01-06 → 2026-08-30
tmax00Znearest30d25 1 QC4.92 [3.28, 6.52]2.55-4.71 [-6.51, -2.85]5.77 [3.71, 7.38]8% [0%, 19%]20%32%+0.10+0.532026-08-06 → 2026-08-30
tmax00Znearest90d25 1 QC4.92 [3.11, 6.70]2.55-4.71 [-6.70, -2.74]5.77 [3.53, 7.49]8% [0%, 22%]20%32%+0.10+0.532026-08-06 → 2026-08-30
tmax00Znearest365d31 1 QC4.96 [3.50, 6.52]2.51-4.79 [-6.52, -3.13]5.76 [3.86, 7.32]6% [0%, 16%]19%32%+0.15+0.562026-01-06 → 2026-08-30
tmax00Znearestall31 1 QC4.96 [3.52, 6.44]2.51-4.79 [-6.44, -3.23]5.76 [3.98, 7.25]6% [0%, 17%]19%32%+0.15+0.562026-01-06 → 2026-08-30
tmax12Zbilinear30d25 1 QC5.34 [4.00, 6.76]2.53-5.20 [-6.76, -3.69]6.13 [4.30, 7.56]4% [0%, 11%]12%28%+0.02+0.542026-08-06 → 2026-08-30
tmax12Zbilinear90d25 1 QC5.34 [3.84, 6.89]2.53-5.20 [-6.89, -3.54]6.13 [4.09, 7.76]4% [0%, 11%]12%28%+0.02+0.542026-08-06 → 2026-08-30
tmax12Zbilinear365d30 1 QC5.20 [3.98, 6.61]2.50-5.09 [-6.61, -3.75]6.00 [4.38, 7.49]3% [0%, 10%]17%30%+0.13+0.572026-01-06 → 2026-08-30
tmax12Zbilinearall30 1 QC5.20 [3.92, 6.60]2.50-5.09 [-6.60, -3.75]6.00 [4.36, 7.45]3% [0%, 10%]17%30%+0.13+0.572026-01-06 → 2026-08-30
tmax12Znearest30d25 1 QC5.19 [3.84, 6.61]2.53-5.05 [-6.61, -3.53]6.00 [4.16, 7.43]4% [0%, 11%]12%24%+0.05+0.542026-08-06 → 2026-08-30
tmax12Znearest90d25 1 QC5.19 [3.65, 6.73]2.53-5.05 [-6.73, -3.40]6.00 [3.95, 7.63]4% [0%, 11%]12%24%+0.05+0.542026-08-06 → 2026-08-30
tmax12Znearest365d30 1 QC5.08 [3.85, 6.49]2.50-4.96 [-6.49, -3.61]5.89 [4.27, 7.39]3% [0%, 10%]17%27%+0.15+0.572026-01-06 → 2026-08-30
tmax12Znearestall30 1 QC5.08 [3.78, 6.47]2.50-4.96 [-6.47, -3.60]5.89 [4.23, 7.30]3% [0%, 10%]17%27%+0.15+0.572026-01-06 → 2026-08-30
tmin00Zbilinear30d25 1 QC3.52 [2.68, 4.60]3.45-0.65 [-2.93, 0.93]4.27 [3.19, 5.41]12% [4%, 22%]28%48%+0.37+0.382026-08-06 → 2026-08-30
tmin00Zbilinear90d25 1 QC3.52 [2.56, 4.70]3.45-0.65 [-3.45, 1.06]4.27 [3.06, 5.51]12% [0%, 23%]28%48%+0.37+0.382026-08-06 → 2026-08-30
tmin00Zbilinear365d31 1 QC3.43 [2.55, 4.49]3.35-0.85 [-3.09, 0.67]4.26 [3.14, 5.39]16% [6%, 29%]32%48%+0.43+0.422026-01-06 → 2026-08-30
tmin00Zbilinearall31 1 QC3.43 [2.54, 4.47]3.35-0.85 [-3.06, 0.65]4.26 [3.16, 5.39]16% [7%, 31%]32%48%+0.43+0.422026-01-06 → 2026-08-30
tmin00Znearest30d25 1 QC3.57 [2.70, 4.65]3.50-0.61 [-2.89, 0.98]4.33 [3.20, 5.48]12% [4%, 22%]28%48%+0.36+0.372026-08-06 → 2026-08-30
tmin00Znearest90d25 1 QC3.57 [2.58, 4.74]3.50-0.61 [-3.44, 1.11]4.33 [3.07, 5.57]12% [0%, 23%]28%48%+0.36+0.372026-08-06 → 2026-08-30
tmin00Znearest365d31 1 QC3.45 [2.56, 4.52]3.37-0.81 [-3.07, 0.71]4.30 [3.14, 5.42]16% [6%, 29%]32%48%+0.43+0.422026-01-06 → 2026-08-30
tmin00Znearestall31 1 QC3.45 [2.53, 4.49]3.37-0.81 [-3.06, 0.73]4.30 [3.14, 5.40]16% [7%, 31%]32%48%+0.43+0.422026-01-06 → 2026-08-30
tmin12Zbilinear30d25 1 QC3.46 [2.28, 4.90]3.15-1.56 [-3.38, -0.18]4.31 [3.04, 5.51]20% [6%, 36%]36%52%+0.38+0.442026-08-06 → 2026-08-30
tmin12Zbilinear90d25 1 QC3.46 [2.00, 5.03]3.15-1.56 [-3.84, 0.01]4.31 [2.57, 5.59]20% [4%, 38%]36%52%+0.38+0.442026-08-06 → 2026-08-30
tmin12Zbilinear365d30 1 QC3.20 [1.99, 4.62]3.03-1.31 [-3.14, 0.04]4.07 [2.67, 5.31]27% [8%, 50%]40%53%+0.48+0.472026-01-06 → 2026-08-30
tmin12Zbilinearall30 1 QC3.20 [1.94, 4.49]3.03-1.31 [-3.13, 0.05]4.07 [2.62, 5.23]27% [10%, 50%]40%53%+0.48+0.472026-01-06 → 2026-08-30
tmin12Znearest30d25 1 QC3.52 [2.32, 4.99]3.25-1.56 [-3.39, -0.13]4.39 [3.04, 5.65]24% [8%, 38%]32%52%+0.37+0.422026-08-06 → 2026-08-30
tmin12Znearest90d25 1 QC3.52 [2.01, 5.12]3.25-1.56 [-3.87, 0.04]4.39 [2.62, 5.74]24% [5%, 40%]32%52%+0.37+0.422026-08-06 → 2026-08-30
tmin12Znearest365d30 1 QC3.24 [1.96, 4.69]3.08-1.31 [-3.14, 0.03]4.13 [2.62, 5.41]30% [12%, 50%]37%53%+0.47+0.462026-01-06 → 2026-08-30
tmin12Znearestall30 1 QC3.24 [1.94, 4.58]3.08-1.31 [-3.18, 0.11]4.13 [2.57, 5.32]30% [14%, 50%]37%53%+0.47+0.462026-01-06 → 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 KPHX, lead day 5, 00Z bilinear tmax+20+100-10-202026-08-06: -1.35 °F2026-08-07: -5.55 °F2026-08-08: -5.01 °F2026-08-09: -2.09 °F2026-08-10: -2.15 °F2026-08-11: -1.6 °F2026-08-12: -5.18 °F2026-08-13: -2.39 °F2026-08-14: +2.47 °F2026-08-15: -3.3 °F2026-08-16: -4.79 °F2026-08-17: -4.77 °F2026-08-18: -5.32 °F2026-08-19: -4.31 °F2026-08-20: -4.45 °F2026-08-21: -8.54 °F2026-08-22: -12.14 °F2026-08-23: -10.44 °F2026-08-24: -0.57 °F2026-08-25: -6.52 °F2026-08-26: -8.48 °F2026-08-27: -3.02 °F2026-08-28: -3.85 °F2026-08-29: -10.73 °F2026-08-30: -7.56 °F2026-08-062026-08-30°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 (25 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-7.56
2026-08-29-10.73
2026-08-28-3.85
2026-08-27-3.02
2026-08-26-8.48
2026-08-25-6.52
2026-08-24-0.57
2026-08-23-10.44
2026-08-22-12.14
2026-08-21-8.54
2026-08-20-4.45
2026-08-19-4.31
2026-08-18-5.32
2026-08-17-4.77
2026-08-16-4.79
2026-08-15-3.30
2026-08-14+2.47
2026-08-13-2.39
2026-08-12-5.18
2026-08-11-1.60
2026-08-10-2.15
2026-08-09-2.09
2026-08-08-5.01
2026-08-07-5.55
2026-08-06-1.35

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KPHX, lead day 5-20 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: 2 days-10 to -8 °F: 3 days-8 to -6 °F: 4 days-6 to -4 °F: 8 days-4 to -2 °F: 8 days-2 to 0 °F: 4 days0 to 2 °F: 0 days2 to 4 °F: 1 day4 to 6 °F: 0 days6 to 8 °F: 0 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| 4.77 · P90 |e| 8.96 °F-200+20 °Fn = 31 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
-12.00-10.002
-10.00-8.003
-8.00-6.004
-6.00-4.008
-4.00-2.008
-2.00+0.004
+0.00+2.000
+2.00+4.001
+4.00+6.000
+6.00+8.000
+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
2026-08255.06 -4.87
2026-0165.16 -5.16

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-06 → 2026-08-30 31
GraphCast (IFS init)2026-01-06 → 2026-08-30 31
GraphCast (IFS init)2026-01-06 → 2026-08-30 30
GraphCast (IFS init)2026-01-06 → 2026-08-30 30

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 25 +0.92 [-0.32, 2.04] no
NCEP GFS 25 +1.05 [0.16, 2.48] yes
ECMWF IFS HRES 18 +2.11 [-1.32, 3.33] no
Persistence (baseline) 25 -0.38 [-3.41, 2.60] no

Cite this page

ShortCastCheck, KPHX graphcast_ifs lead 5, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KPHX/model/graphcast_ifs/lead/5/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KPHX (Phoenix Sky Harbor), model graphcast_ifs, lead day 5. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KPHX/model/graphcast_ifs/lead/5/

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