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

Phoenix Sky Harbor · GraphCast (IFS init) · lead day 7

KPHX · graphcast_ifs · lead 7

Target day = initialization date + 7 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
tmax00Zbilinear30d23 1 QC6.94 [4.44, 9.70]3.80-6.66 [-9.70, -3.66]8.20 [5.02, 10.87]0% [0%, 0%]4%13%-0.30+0.302026-08-08 → 2026-08-30
tmax00Zbilinear90d23 1 QC6.94 [4.28, 10.04]3.80-6.66 [-10.04, -3.56]8.20 [4.77, 11.10]0% [0%, 0%]4%13%-0.30+0.302026-08-08 → 2026-08-30
tmax00Zbilinear365d29 1 QC6.14 [3.60, 8.99]3.59-5.92 [-8.98, -3.22]7.52 [4.41, 10.24]3% [0%, 12%]10%24%-0.14+0.332026-01-08 → 2026-08-30
tmax00Zbilinearall29 1 QC6.14 [3.57, 9.32]3.59-5.92 [-9.32, -3.25]7.52 [4.32, 10.54]3% [0%, 13%]10%24%-0.14+0.332026-01-08 → 2026-08-30
tmax00Znearest30d23 1 QC6.78 [4.35, 9.51]3.76-6.49 [-9.51, -3.56]8.04 [4.89, 10.68]0% [0%, 0%]4%13%-0.27+0.302026-08-08 → 2026-08-30
tmax00Znearest90d23 1 QC6.78 [4.17, 9.86]3.76-6.49 [-9.86, -3.43]8.04 [4.64, 10.78]0% [0%, 0%]4%13%-0.27+0.302026-08-08 → 2026-08-30
tmax00Znearest365d29 1 QC6.02 [3.56, 8.81]3.52-5.79 [-8.79, -3.16]7.37 [4.29, 10.06]3% [0%, 12%]10%24%-0.12+0.342026-01-08 → 2026-08-30
tmax00Znearestall29 1 QC6.02 [3.54, 9.13]3.52-5.79 [-9.13, -3.16]7.37 [4.20, 10.35]3% [0%, 13%]10%24%-0.12+0.342026-01-08 → 2026-08-30
tmax12Zbilinear30d23 1 QC6.50 [4.31, 8.85]3.01-6.38 [-8.85, -4.03]7.45 [4.94, 9.68]4% [0%, 12%]9%13%-0.21+0.442026-08-08 → 2026-08-30
tmax12Zbilinear90d23 1 QC6.50 [4.26, 9.04]3.01-6.38 [-9.04, -3.93]7.45 [4.90, 9.70]4% [0%, 13%]9%13%-0.21+0.442026-08-08 → 2026-08-30
tmax12Zbilinear365d28 1 QC5.92 [3.80, 8.25]2.93-5.82 [-8.25, -3.63]6.90 [4.27, 9.12]4% [0%, 11%]11%18%-0.11+0.442026-01-08 → 2026-08-30
tmax12Zbilinearall28 1 QC5.92 [3.73, 8.55]2.93-5.82 [-8.55, -3.57]6.90 [4.12, 9.34]4% [0%, 11%]11%18%-0.11+0.442026-01-08 → 2026-08-30
tmax12Znearest30d23 1 QC6.34 [4.16, 8.70]2.99-6.23 [-8.70, -3.90]7.31 [4.77, 9.52]4% [0%, 12%]9%13%-0.19+0.442026-08-08 → 2026-08-30
tmax12Znearest90d23 1 QC6.34 [4.13, 8.87]2.99-6.23 [-8.87, -3.78]7.31 [4.73, 9.55]4% [0%, 13%]9%13%-0.19+0.442026-08-08 → 2026-08-30
tmax12Znearest365d28 1 QC5.80 [3.74, 8.11]2.89-5.70 [-8.11, -3.58]6.78 [4.20, 8.99]4% [0%, 11%]11%18%-0.09+0.452026-01-08 → 2026-08-30
tmax12Znearestall28 1 QC5.80 [3.69, 8.44]2.89-5.70 [-8.44, -3.52]6.78 [4.07, 9.19]4% [0%, 11%]11%18%-0.09+0.452026-01-08 → 2026-08-30
tmin00Zbilinear30d23 1 QC3.84 [2.99, 4.64]3.69-0.95 [-3.58, 1.08]4.50 [3.65, 5.26]13% [0%, 25%]22%43%+0.34+0.372026-08-08 → 2026-08-30
tmin00Zbilinear90d23 1 QC3.84 [2.86, 4.75]3.69-0.95 [-3.95, 1.20]4.50 [3.47, 5.32]13% [0%, 26%]22%43%+0.34+0.372026-08-08 → 2026-08-30
tmin00Zbilinear365d29 1 QC4.17 [3.21, 5.12]4.04-0.98 [-3.53, 1.11]4.78 [3.86, 5.62]10% [0%, 21%]17%34%+0.31+0.342026-01-08 → 2026-08-30
tmin00Zbilinearall29 1 QC4.17 [3.23, 5.18]4.04-0.98 [-3.74, 1.06]4.78 [3.81, 5.64]10% [0%, 21%]17%34%+0.31+0.342026-01-08 → 2026-08-30
tmin00Znearest30d23 1 QC3.85 [3.05, 4.62]3.71-0.86 [-3.51, 1.16]4.50 [3.67, 5.25]13% [0%, 25%]22%48%+0.34+0.362026-08-08 → 2026-08-30
tmin00Znearest90d23 1 QC3.85 [2.94, 4.69]3.71-0.86 [-3.94, 1.29]4.50 [3.51, 5.32]13% [0%, 26%]22%48%+0.34+0.362026-08-08 → 2026-08-30
tmin00Znearest365d29 1 QC4.15 [3.24, 5.00]4.04-0.86 [-3.41, 1.23]4.74 [3.87, 5.51]10% [0%, 21%]17%38%+0.31+0.342026-01-08 → 2026-08-30
tmin00Znearestall29 1 QC4.15 [3.27, 5.06]4.04-0.86 [-3.66, 1.11]4.74 [3.80, 5.53]10% [0%, 21%]17%38%+0.31+0.342026-01-08 → 2026-08-30
tmin12Zbilinear30d23 1 QC3.99 [2.79, 5.07]3.65-1.61 [-3.89, 0.16]4.65 [3.50, 5.55]9% [0%, 19%]26%35%+0.32+0.372026-08-08 → 2026-08-30
tmin12Zbilinear90d23 1 QC3.99 [2.60, 5.13]3.65-1.61 [-4.30, 0.25]4.65 [3.24, 5.58]9% [0%, 22%]26%35%+0.32+0.372026-08-08 → 2026-08-30
tmin12Zbilinear365d28 1 QC4.18 [2.93, 5.32]3.96-1.68 [-3.83, 0.13]4.95 [3.75, 6.04]11% [0%, 21%]25%32%+0.33+0.372026-01-08 → 2026-08-30
tmin12Zbilinearall28 1 QC4.18 [2.91, 5.36]3.96-1.68 [-4.09, 0.08]4.95 [3.60, 6.11]11% [0%, 21%]25%32%+0.33+0.372026-01-08 → 2026-08-30
tmin12Znearest30d23 1 QC4.02 [2.81, 5.12]3.71-1.60 [-3.88, 0.18]4.69 [3.50, 5.60]13% [0%, 25%]26%35%+0.31+0.362026-08-08 → 2026-08-30
tmin12Znearest90d23 1 QC4.02 [2.58, 5.18]3.71-1.60 [-4.31, 0.24]4.69 [3.25, 5.65]13% [0%, 26%]26%35%+0.31+0.362026-08-08 → 2026-08-30
tmin12Znearest365d28 1 QC4.19 [2.93, 5.31]3.98-1.64 [-3.79, 0.13]4.93 [3.69, 5.97]14% [0%, 27%]25%32%+0.33+0.362026-01-08 → 2026-08-30
tmin12Znearestall28 1 QC4.19 [2.96, 5.33]3.98-1.64 [-4.04, 0.14]4.93 [3.64, 5.95]14% [0%, 27%]25%32%+0.33+0.362026-01-08 → 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 7, 00Z bilinear tmax+20+100-10-202026-08-08: -11.13 °F2026-08-09: -4.36 °F2026-08-10: -4.34 °F2026-08-11: -2.01 °F2026-08-12: -6.89 °F2026-08-13: -1.86 °F2026-08-14: +3.24 °F2026-08-15: -2.41 °F2026-08-16: -3.24 °F2026-08-17: -5.57 °F2026-08-18: -10.4 °F2026-08-19: -5.46 °F2026-08-20: -5.72 °F2026-08-21: -5.66 °F2026-08-22: -12.49 °F2026-08-23: -18.94 °F2026-08-24: -13.46 °F2026-08-25: -13.27 °F2026-08-26: -10.38 °F2026-08-27: -5.51 °F2026-08-28: -3.59 °F2026-08-29: -4.56 °F2026-08-30: -5.19 °F2026-08-082026-08-30°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 (23 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-5.19
2026-08-29-4.56
2026-08-28-3.59
2026-08-27-5.51
2026-08-26-10.38
2026-08-25-13.27
2026-08-24-13.46
2026-08-23-18.94
2026-08-22-12.49
2026-08-21-5.66
2026-08-20-5.72
2026-08-19-5.46
2026-08-18-10.40
2026-08-17-5.57
2026-08-16-3.24
2026-08-15-2.41
2026-08-14+3.24
2026-08-13-1.86
2026-08-12-6.89
2026-08-11-2.01
2026-08-10-4.34
2026-08-09-4.36
2026-08-08-11.13

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KPHX, lead day 7-20 to -18 °F: 1 day-18 to -16 °F: 0 days-16 to -14 °F: 0 days-14 to -12 °F: 3 days-12 to -10 °F: 3 days-10 to -8 °F: 1 day-8 to -6 °F: 1 day-6 to -4 °F: 9 days-4 to -2 °F: 7 days-2 to 0 °F: 3 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| 5.19 · P90 |e| 12.65 °F-200+20 °Fn = 29 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
-20.00-18.001
-18.00-16.000
-16.00-14.000
-14.00-12.003
-12.00-10.003
-10.00-8.001
-8.00-6.001
-6.00-4.009
-4.00-2.007
-2.00+0.003
+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
2026-08236.94 -6.66
2026-0163.06 -3.06

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-08 → 2026-08-30 29
GraphCast (IFS init)2026-01-08 → 2026-08-30 29
GraphCast (IFS init)2026-01-08 → 2026-08-30 28
GraphCast (IFS init)2026-01-08 → 2026-08-30 28

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 23 +1.44 [-0.83, 3.34] no
NCEP GFS 23 +2.63 [0.09, 5.67] yes
ECMWF IFS HRES 18 +4.37 [0.81, 7.91] yes
Persistence (baseline) 23 +1.59 [-1.25, 5.07] no

Cite this page

ShortCastCheck, KPHX graphcast_ifs lead 7, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KPHX/model/graphcast_ifs/lead/7/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KPHX (Phoenix Sky Harbor), model graphcast_ifs, lead day 7. 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/7/

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