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

Phoenix Sky Harbor · NCEP GFS · lead day 2

KPHX · gfs · lead 2

Target day = initialization date + 2 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, gfs-0p25, 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
tmax00Zbilinear30d28 1 QC2.75 [2.00, 3.52]1.78-2.42 [-3.29, -1.52]3.29 [2.47, 3.98]18% [4%, 32%]39%61%+0.42+0.622026-08-03 → 2026-08-30
tmax00Zbilinear90d28 1 QC2.75 [1.94, 3.63]1.78-2.42 [-3.45, -1.32]3.29 [2.43, 4.10]18% [0%, 33%]39%61%+0.42+0.622026-08-03 → 2026-08-30
tmax00Zbilinear365d28 1 QC2.75 [1.93, 3.71]1.78-2.42 [-3.59, -1.19]3.29 [2.41, 4.16]18% [0%, 33%]39%61%+0.42+0.622026-08-03 → 2026-08-30
tmax00Zbilinearall28 1 QC2.75 [1.90, 3.64]1.78-2.42 [-3.47, -1.30]3.29 [2.38, 4.08]18% [0%, 33%]39%61%+0.42+0.622026-08-03 → 2026-08-30
tmax00Znearest30d28 1 QC2.73 [1.97, 3.51]1.83-2.36 [-3.22, -1.47]3.28 [2.47, 3.97]14% [0%, 30%]39%64%+0.42+0.612026-08-03 → 2026-08-30
tmax00Znearest90d28 1 QC2.73 [1.93, 3.63]1.83-2.36 [-3.39, -1.28]3.28 [2.44, 4.11]14% [0%, 31%]39%64%+0.42+0.612026-08-03 → 2026-08-30
tmax00Znearest365d28 1 QC2.73 [1.93, 3.73]1.83-2.36 [-3.55, -1.17]3.28 [2.40, 4.15]14% [0%, 33%]39%64%+0.42+0.612026-08-03 → 2026-08-30
tmax00Znearestall28 1 QC2.73 [1.89, 3.65]1.83-2.36 [-3.45, -1.24]3.28 [2.38, 4.08]14% [0%, 32%]39%64%+0.42+0.612026-08-03 → 2026-08-30
tmax12Zbilinear30d28 1 QC2.96 [2.26, 3.75]1.98-2.52 [-3.51, -1.47]3.58 [2.58, 4.43]11% [0%, 21%]39%57%+0.37+0.582026-08-03 → 2026-08-30
tmax12Zbilinear90d28 1 QC2.96 [2.22, 3.91]1.98-2.52 [-3.65, -1.31]3.58 [2.49, 4.56]11% [0%, 21%]39%57%+0.37+0.582026-08-03 → 2026-08-30
tmax12Zbilinear365d28 1 QC2.96 [2.21, 4.01]1.98-2.52 [-3.77, -1.26]3.58 [2.49, 4.63]11% [0%, 21%]39%57%+0.37+0.582026-08-03 → 2026-08-30
tmax12Zbilinearall28 1 QC2.96 [2.20, 3.94]1.98-2.52 [-3.82, -1.29]3.58 [2.48, 4.59]11% [0%, 21%]39%57%+0.37+0.582026-08-03 → 2026-08-30
tmax12Znearest30d28 1 QC2.96 [2.30, 3.72]2.06-2.47 [-3.48, -1.40]3.60 [2.66, 4.42]11% [0%, 21%]43%61%+0.37+0.572026-08-03 → 2026-08-30
tmax12Znearest90d28 1 QC2.96 [2.28, 3.89]2.06-2.47 [-3.59, -1.22]3.60 [2.58, 4.54]11% [0%, 21%]43%61%+0.37+0.572026-08-03 → 2026-08-30
tmax12Znearest365d28 1 QC2.96 [2.31, 3.97]2.06-2.47 [-3.74, -1.22]3.60 [2.59, 4.62]11% [0%, 21%]43%61%+0.37+0.572026-08-03 → 2026-08-30
tmax12Znearestall28 1 QC2.96 [2.26, 3.92]2.06-2.47 [-3.79, -1.18]3.60 [2.56, 4.56]11% [0%, 21%]43%61%+0.37+0.572026-08-03 → 2026-08-30
tmin00Zbilinear30d28 1 QC4.23 [2.94, 5.44]3.41+3.16 [0.81, 5.10]5.40 [3.73, 6.80]18% [3%, 34%]36%46%+0.17+0.322026-08-03 → 2026-08-30
tmin00Zbilinear90d28 1 QC4.23 [2.59, 5.39]3.41+3.16 [0.33, 5.12]5.40 [3.26, 6.83]18% [4%, 40%]36%46%+0.17+0.322026-08-03 → 2026-08-30
tmin00Zbilinear365d28 1 QC4.23 [2.71, 5.46]3.41+3.16 [0.24, 5.17]5.40 [3.51, 6.82]18% [0%, 37%]36%46%+0.17+0.322026-08-03 → 2026-08-30
tmin00Zbilinearall28 1 QC4.23 [2.59, 5.57]3.41+3.16 [0.11, 5.23]5.40 [3.24, 6.95]18% [2%, 40%]36%46%+0.17+0.322026-08-03 → 2026-08-30
tmin00Znearest30d28 1 QC5.10 [3.47, 6.51]3.42+4.29 [1.77, 6.32]6.20 [4.34, 7.67]7% [0%, 17%]18%39%-0.01+0.322026-08-03 → 2026-08-30
tmin00Znearest90d28 1 QC5.10 [2.99, 6.53]3.42+4.29 [1.31, 6.34]6.20 [3.75, 7.70]7% [0%, 20%]18%39%-0.01+0.322026-08-03 → 2026-08-30
tmin00Znearest365d28 1 QC5.10 [3.18, 6.58]3.42+4.29 [1.12, 6.39]6.20 [4.01, 7.75]7% [0%, 20%]18%39%-0.01+0.322026-08-03 → 2026-08-30
tmin00Znearestall28 1 QC5.10 [2.95, 6.69]3.42+4.29 [0.99, 6.46]6.20 [3.75, 7.82]7% [0%, 20%]18%39%-0.01+0.322026-08-03 → 2026-08-30
tmin12Zbilinear30d28 1 QC4.10 [2.84, 5.37]3.11+2.87 [0.38, 4.84]4.87 [3.39, 6.04]11% [3%, 18%]25%39%+0.19+0.382026-08-03 → 2026-08-30
tmin12Zbilinear90d28 1 QC4.10 [2.56, 5.37]3.11+2.87 [-0.35, 4.87]4.87 [2.97, 6.09]11% [3%, 20%]25%39%+0.19+0.382026-08-03 → 2026-08-30
tmin12Zbilinear365d28 1 QC4.10 [2.64, 5.41]3.11+2.87 [-0.29, 4.92]4.87 [3.07, 6.11]11% [0%, 19%]25%39%+0.19+0.382026-08-03 → 2026-08-30
tmin12Zbilinearall28 1 QC4.10 [2.48, 5.57]3.11+2.87 [-0.45, 4.95]4.87 [2.89, 6.27]11% [0%, 20%]25%39%+0.19+0.382026-08-03 → 2026-08-30
tmin12Znearest30d28 1 QC4.96 [3.06, 6.53]3.17+4.24 [1.69, 6.26]5.81 [3.87, 7.16]7% [0%, 23%]21%29%+0.02+0.372026-08-03 → 2026-08-30
tmin12Znearest90d28 1 QC4.96 [2.56, 6.54]3.17+4.24 [0.91, 6.28]5.81 [3.19, 7.23]7% [0%, 28%]21%29%+0.02+0.372026-08-03 → 2026-08-30
tmin12Znearest365d28 1 QC4.96 [2.64, 6.59]3.17+4.24 [0.98, 6.37]5.81 [3.15, 7.24]7% [0%, 27%]21%29%+0.02+0.372026-08-03 → 2026-08-30
tmin12Znearestall28 1 QC4.96 [2.27, 6.73]3.17+4.24 [0.78, 6.39]5.81 [2.83, 7.40]7% [0%, 30%]21%29%+0.02+0.372026-08-03 → 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 NCEP GFS at KPHX, lead day 2, 00Z bilinear tmax+10+50-5-102026-08-03: -5.14 °F2026-08-04: +2.26 °F2026-08-05: +1.48 °F2026-08-06: -0 °F2026-08-07: -2.2 °F2026-08-08: -2.85 °F2026-08-09: -1.56 °F2026-08-10: -2.37 °F2026-08-11: -0.11 °F2026-08-12: -0.82 °F2026-08-13: -1.52 °F2026-08-14: -0.43 °F2026-08-15: -3.31 °F2026-08-16: -5.56 °F2026-08-17: -4.82 °F2026-08-18: -5.15 °F2026-08-19: -1.28 °F2026-08-20: +0.94 °F2026-08-21: -4.52 °F2026-08-22: -5.21 °F2026-08-23: -2.57 °F2026-08-24: -1.7 °F2026-08-25: -3.04 °F2026-08-26: -3.2 °F2026-08-27: -2.22 °F2026-08-28: -1.81 °F2026-08-29: -7.14 °F2026-08-30: -3.89 °F2026-08-032026-08-30°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 (28 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-3.89
2026-08-29-7.14
2026-08-28-1.81
2026-08-27-2.22
2026-08-26-3.20
2026-08-25-3.04
2026-08-24-1.70
2026-08-23-2.57
2026-08-22-5.21
2026-08-21-4.52
2026-08-20+0.94
2026-08-19-1.28
2026-08-18-5.15
2026-08-17-4.82
2026-08-16-5.56
2026-08-15-3.31
2026-08-14-0.43
2026-08-13-1.52
2026-08-12-0.82
2026-08-11-0.11
2026-08-10-2.37
2026-08-09-1.56
2026-08-08-2.85
2026-08-07-2.20
2026-08-06-0.00
2026-08-05+1.48
2026-08-04+2.26
2026-08-03-5.14

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KPHX, lead day 2-10 to -9 °F: 0 days-9 to -8 °F: 0 days-8 to -7 °F: 1 day-7 to -6 °F: 0 days-6 to -5 °F: 4 days-5 to -4 °F: 2 days-4 to -3 °F: 4 days-3 to -2 °F: 5 days-2 to -1 °F: 5 days-1 to 0 °F: 4 days0 to 1 °F: 1 day1 to 2 °F: 1 day2 to 3 °F: 1 day3 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| 2.32 · P90 |e| 5.17 °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
-10.00-9.000
-9.00-8.000
-8.00-7.001
-7.00-6.000
-6.00-5.004
-5.00-4.002
-4.00-3.004
-3.00-2.005
-2.00-1.005
-1.00+0.004
+0.00+1.001
+1.00+2.001
+2.00+3.001
+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
2026-08282.75 -2.42

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-03 → 2026-08-30 28
NCEP GFS2026-08-03 → 2026-08-30 28
NCEP GFS2026-08-03 → 2026-08-30 28
NCEP GFS2026-08-03 → 2026-08-30 28

Compared with other models

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

Other modelCommon days MAE difference °FDistinguishable
ECMWF AIFS Single 28 -0.73 [-2.11, 0.66] no
Aurora (IFS init) 1 -6.53 [-6.53, -6.53] yes
FourCastNet v2 (IFS init) 1 -7.81 [-7.81, -7.81] yes
GraphCast (IFS init) 26 -0.86 [-2.04, 0.19] no
ECMWF IFS HRES 23 +0.27 [-1.14, 1.48] no
Pangu-Weather (IFS init) 1 -3.10 [-3.10, -3.10] yes
Persistence (baseline) 28 -1.96 [-2.90, -0.80] yes

Cite this page

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

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

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