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

Philadelphia Intl · GraphCast (GFS init) · lead day 1

KPHL · graphcast_gfs · lead 1

Target day = initialization date + 1 day. 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 2026-08-28 — 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
tmax00Zbilinear30d1 1 QC6.35 [6.35, 6.35]0.00-6.35 [-6.35, -6.35]6.35 [6.35, 6.35]0% [0%, 0%]0%0%-0.27—2026-08-30 → 2026-08-30
tmax00Zbilinear90d1 1 QC6.35 [6.35, 6.35]0.00-6.35 [-6.35, -6.35]6.35 [6.35, 6.35]0% [0%, 0%]0%0%-0.27—2026-08-30 → 2026-08-30
tmax00Zbilinear365d1 1 QC6.35 [6.35, 6.35]0.00-6.35 [-6.35, -6.35]6.35 [6.35, 6.35]0% [0%, 0%]0%0%-0.27—2026-08-30 → 2026-08-30
tmax00Zbilinearall1 1 QC6.35 [6.35, 6.35]0.00-6.35 [-6.35, -6.35]6.35 [6.35, 6.35]0% [0%, 0%]0%0%-0.27—2026-08-30 → 2026-08-30
tmax00Znearest30d1 1 QC5.65 [5.65, 5.65]0.00-5.65 [-5.65, -5.65]5.65 [5.65, 5.65]0% [0%, 0%]0%0%-0.13—2026-08-30 → 2026-08-30
tmax00Znearest90d1 1 QC5.65 [5.65, 5.65]0.00-5.65 [-5.65, -5.65]5.65 [5.65, 5.65]0% [0%, 0%]0%0%-0.13—2026-08-30 → 2026-08-30
tmax00Znearest365d1 1 QC5.65 [5.65, 5.65]0.00-5.65 [-5.65, -5.65]5.65 [5.65, 5.65]0% [0%, 0%]0%0%-0.13—2026-08-30 → 2026-08-30
tmax00Znearestall1 1 QC5.65 [5.65, 5.65]0.00-5.65 [-5.65, -5.65]5.65 [5.65, 5.65]0% [0%, 0%]0%0%-0.13—2026-08-30 → 2026-08-30
tmax12Zbilinear30d2 1 QC4.53 [4.07, 4.98]0.45-4.53 [-4.98, -4.07]4.55 [4.07, 4.98]0% [0%, 0%]0%0%+0.09+0.912026-08-29 → 2026-08-30
tmax12Zbilinear90d2 1 QC4.53 [4.07, 4.98]0.45-4.53 [-4.98, -4.07]4.55 [4.07, 4.98]0% [0%, 0%]0%0%+0.09+0.912026-08-29 → 2026-08-30
tmax12Zbilinear365d2 1 QC4.53 [4.07, 4.98]0.45-4.53 [-4.98, -4.07]4.55 [4.07, 4.98]0% [0%, 0%]0%0%+0.09+0.912026-08-29 → 2026-08-30
tmax12Zbilinearall2 1 QC4.53 [4.07, 4.98]0.45-4.53 [-4.98, -4.07]4.55 [4.07, 4.98]0% [0%, 0%]0%0%+0.09+0.912026-08-29 → 2026-08-30
tmax12Znearest30d2 1 QC4.25 [3.90, 4.60]0.35-4.25 [-4.60, -3.90]4.27 [3.90, 4.60]0% [0%, 0%]0%0%+0.15+0.932026-08-29 → 2026-08-30
tmax12Znearest90d2 1 QC4.25 [3.90, 4.60]0.35-4.25 [-4.60, -3.90]4.27 [3.90, 4.60]0% [0%, 0%]0%0%+0.15+0.932026-08-29 → 2026-08-30
tmax12Znearest365d2 1 QC4.25 [3.90, 4.60]0.35-4.25 [-4.60, -3.90]4.27 [3.90, 4.60]0% [0%, 0%]0%0%+0.15+0.932026-08-29 → 2026-08-30
tmax12Znearestall2 1 QC4.25 [3.90, 4.60]0.35-4.25 [-4.60, -3.90]4.27 [3.90, 4.60]0% [0%, 0%]0%0%+0.15+0.932026-08-29 → 2026-08-30
tmin00Zbilinear30d1 1 QC1.56 [1.56, 1.56]0.00+1.56 [1.56, 1.56]1.56 [1.56, 1.56]0% [0%, 0%]100%100%——2026-08-30 → 2026-08-30
tmin00Zbilinear90d1 1 QC1.56 [1.56, 1.56]0.00+1.56 [1.56, 1.56]1.56 [1.56, 1.56]0% [0%, 0%]100%100%——2026-08-30 → 2026-08-30
tmin00Zbilinear365d1 1 QC1.56 [1.56, 1.56]0.00+1.56 [1.56, 1.56]1.56 [1.56, 1.56]0% [0%, 0%]100%100%——2026-08-30 → 2026-08-30
tmin00Zbilinearall1 1 QC1.56 [1.56, 1.56]0.00+1.56 [1.56, 1.56]1.56 [1.56, 1.56]0% [0%, 0%]100%100%——2026-08-30 → 2026-08-30
tmin00Znearest30d1 1 QC2.20 [2.20, 2.20]0.00+2.20 [2.20, 2.20]2.20 [2.20, 2.20]0% [0%, 0%]0%100%——2026-08-30 → 2026-08-30
tmin00Znearest90d1 1 QC2.20 [2.20, 2.20]0.00+2.20 [2.20, 2.20]2.20 [2.20, 2.20]0% [0%, 0%]0%100%——2026-08-30 → 2026-08-30
tmin00Znearest365d1 1 QC2.20 [2.20, 2.20]0.00+2.20 [2.20, 2.20]2.20 [2.20, 2.20]0% [0%, 0%]0%100%——2026-08-30 → 2026-08-30
tmin00Znearestall1 1 QC2.20 [2.20, 2.20]0.00+2.20 [2.20, 2.20]2.20 [2.20, 2.20]0% [0%, 0%]0%100%——2026-08-30 → 2026-08-30
tmin12Zbilinear30d2 1 QC1.38 [1.26, 1.51]0.13+1.38 [1.26, 1.51]1.39 [1.26, 1.51]0% [0%, 0%]100%100%+0.54+0.962026-08-29 → 2026-08-30
tmin12Zbilinear90d2 1 QC1.38 [1.26, 1.51]0.13+1.38 [1.26, 1.51]1.39 [1.26, 1.51]0% [0%, 0%]100%100%+0.54+0.962026-08-29 → 2026-08-30
tmin12Zbilinear365d2 1 QC1.38 [1.26, 1.51]0.13+1.38 [1.26, 1.51]1.39 [1.26, 1.51]0% [0%, 0%]100%100%+0.54+0.962026-08-29 → 2026-08-30
tmin12Zbilinearall2 1 QC1.38 [1.26, 1.51]0.13+1.38 [1.26, 1.51]1.39 [1.26, 1.51]0% [0%, 0%]100%100%+0.54+0.962026-08-29 → 2026-08-30
tmin12Znearest30d2 1 QC1.86 [1.72, 2.01]0.14+1.86 [1.72, 2.01]1.87 [1.72, 2.01]0% [0%, 0%]50%100%+0.38+0.952026-08-29 → 2026-08-30
tmin12Znearest90d2 1 QC1.86 [1.72, 2.01]0.14+1.86 [1.72, 2.01]1.87 [1.72, 2.01]0% [0%, 0%]50%100%+0.38+0.952026-08-29 → 2026-08-30
tmin12Znearest365d2 1 QC1.86 [1.72, 2.01]0.14+1.86 [1.72, 2.01]1.87 [1.72, 2.01]0% [0%, 0%]50%100%+0.38+0.952026-08-29 → 2026-08-30
tmin12Znearestall2 1 QC1.86 [1.72, 2.01]0.14+1.86 [1.72, 2.01]1.87 [1.72, 2.01]0% [0%, 0%]50%100%+0.38+0.952026-08-29 → 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 (GFS init) at KPHL, lead day 1, 00Z bilinear tmax+10+50-5-102026-08-30: -6.35 °F2026-08-30°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 (1 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-6.35

Error distribution

Distribution of the signed daily error in °F for GraphCast (GFS init) at KPHL, lead day 1-10 to -9 °F: 0 days-9 to -8 °F: 0 days-8 to -7 °F: 0 days-7 to -6 °F: 1 day-6 to -5 °F: 0 days-5 to -4 °F: 0 days-4 to -3 °F: 0 days-3 to -2 °F: 0 days-2 to -1 °F: 0 days-1 to 0 °F: 0 days0 to 1 °F: 0 days1 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| 6.35 · P90 |e| 6.35 °F-100+10 °Fn = 1 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
-8.00-7.000
-7.00-6.001
-6.00-5.000
-5.00-4.000
-4.00-3.000
-3.00-2.000
-2.00-1.000
-1.00+0.000
+0.00+1.000
+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
2026-0816.35 -6.35

Availability

ModelScored period DaysCoverage
GraphCast (GFS init)2026-08-30 → 2026-08-30 1
GraphCast (GFS init)2026-08-30 → 2026-08-30 1
GraphCast (GFS init)2026-08-29 → 2026-08-30 2
GraphCast (GFS init)2026-08-29 → 2026-08-30 2

Compared with other models

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

Other modelCommon days MAE difference °FDistinguishable
ECMWF AIFS Single 1 +2.10 [2.10, 2.10] yes
Aurora (GFS init) 1 -0.16 [-0.16, -0.16] yes
Aurora (IFS init) 1 +1.51 [1.51, 1.51] yes
FourCastNet v2 (GFS init) 1 +1.63 [1.63, 1.63] yes
FourCastNet v2 (IFS init) 1 +1.10 [1.10, 1.10] yes
NCEP GFS 1 +6.27 [6.27, 6.27] yes
GraphCast (IFS init) 1 +0.26 [0.26, 0.26] yes
ECMWF IFS HRES 1 +3.20 [3.20, 3.20] yes
Pangu-Weather (GFS init) 1 +3.82 [3.82, 3.82] yes
Pangu-Weather (IFS init) 1 +3.04 [3.04, 3.04] yes
Persistence (baseline) 1 +1.35 [1.35, 1.35] yes

Cite this page

ShortCastCheck, KPHL graphcast_gfs lead 1, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KPHL/model/graphcast_gfs/lead/1/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KPHL (Philadelphia Intl), model graphcast_gfs, lead day 1. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KPHL/model/graphcast_gfs/lead/1/

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