Raw model output on the native 0.25° grid — no MOS, no bias correction, no post-processing. Scores understate operational forecast quality. Read the fairness statement →

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

Philadelphia Intl · NCEP GFS · lead day 5

KPHL · gfs · 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, 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
tmax00Zbilinear30d25 1 QC4.33 [2.83, 5.71]4.30-1.96 [-4.02, 0.65]5.66 [3.99, 6.86]24% [8%, 39%]36%44%-0.18-0.202026-08-06 → 2026-08-30
tmax00Zbilinear90d25 1 QC4.33 [2.54, 5.69]4.30-1.96 [-4.10, 1.06]5.66 [3.61, 6.80]24% [8%, 40%]36%44%-0.18-0.202026-08-06 → 2026-08-30
tmax00Zbilinear365d25 1 QC4.33 [2.53, 5.82]4.30-1.96 [-4.26, 1.30]5.66 [3.52, 6.92]24% [7%, 42%]36%44%-0.18-0.202026-08-06 → 2026-08-30
tmax00Zbilinearall25 1 QC4.33 [2.60, 5.79]4.30-1.96 [-4.24, 0.97]5.66 [3.62, 6.86]24% [6%, 43%]36%44%-0.18-0.202026-08-06 → 2026-08-30
tmax00Znearest30d25 1 QC4.35 [2.86, 5.71]4.16-2.31 [-4.30, 0.13]5.71 [3.90, 6.90]24% [7%, 42%]36%40%-0.18-0.162026-08-06 → 2026-08-30
tmax00Znearest90d25 1 QC4.35 [2.60, 5.69]4.16-2.31 [-4.33, 0.49]5.71 [3.54, 6.81]24% [6%, 43%]36%40%-0.18-0.162026-08-06 → 2026-08-30
tmax00Znearest365d25 1 QC4.35 [2.54, 5.82]4.16-2.31 [-4.53, 0.80]5.71 [3.38, 6.90]24% [4%, 43%]36%40%-0.18-0.162026-08-06 → 2026-08-30
tmax00Znearestall25 1 QC4.35 [2.63, 5.75]4.16-2.31 [-4.46, 0.51]5.71 [3.50, 6.88]24% [4%, 44%]36%40%-0.18-0.162026-08-06 → 2026-08-30
tmax12Zbilinear30d25 1 QC3.16 [2.09, 4.37]3.14-1.49 [-2.92, 0.04]4.24 [2.64, 5.53]32% [17%, 46%]44%56%+0.14+0.122026-08-06 → 2026-08-30
tmax12Zbilinear90d25 1 QC3.16 [1.85, 4.34]3.14-1.49 [-2.88, 0.32]4.24 [2.28, 5.58]32% [17%, 48%]44%56%+0.14+0.122026-08-06 → 2026-08-30
tmax12Zbilinear365d25 1 QC3.16 [1.91, 4.51]3.14-1.49 [-3.10, 0.34]4.24 [2.32, 5.71]32% [14%, 50%]44%56%+0.14+0.122026-08-06 → 2026-08-30
tmax12Zbilinearall25 1 QC3.16 [1.83, 4.46]3.14-1.49 [-2.96, 0.23]4.24 [2.29, 5.68]32% [14%, 49%]44%56%+0.14+0.122026-08-06 → 2026-08-30
tmax12Znearest30d25 1 QC3.26 [2.20, 4.51]3.09-1.73 [-3.21, -0.29]4.40 [2.80, 5.71]28% [12%, 41%]40%56%+0.11+0.142026-08-06 → 2026-08-30
tmax12Znearest90d25 1 QC3.26 [1.97, 4.49]3.09-1.73 [-3.20, 0.01]4.40 [2.31, 5.76]28% [12%, 43%]40%56%+0.11+0.142026-08-06 → 2026-08-30
tmax12Znearest365d25 1 QC3.26 [2.02, 4.66]3.09-1.73 [-3.39, -0.04]4.40 [2.36, 5.89]28% [10%, 43%]40%56%+0.11+0.142026-08-06 → 2026-08-30
tmax12Znearestall25 1 QC3.26 [1.98, 4.60]3.09-1.73 [-3.32, -0.01]4.40 [2.34, 5.84]28% [11%, 43%]40%56%+0.11+0.142026-08-06 → 2026-08-30
tmin00Zbilinear30d25 1 QC2.61 [1.75, 3.44]2.61-0.10 [-1.83, 1.47]3.66 [2.17, 4.95]32% [11%, 55%]44%84%+0.13+0.172026-08-06 → 2026-08-30
tmin00Zbilinear90d25 1 QC2.61 [1.63, 3.46]2.61-0.10 [-1.80, 1.68]3.66 [1.92, 4.94]32% [10%, 59%]44%84%+0.13+0.172026-08-06 → 2026-08-30
tmin00Zbilinear365d25 1 QC2.61 [1.65, 3.49]2.61-0.10 [-2.04, 1.92]3.66 [1.89, 4.99]32% [5%, 60%]44%84%+0.13+0.172026-08-06 → 2026-08-30
tmin00Zbilinearall25 1 QC2.61 [1.57, 3.48]2.61-0.10 [-1.94, 1.64]3.66 [1.83, 4.97]32% [6%, 62%]44%84%+0.13+0.172026-08-06 → 2026-08-30
tmin00Znearest30d25 1 QC2.48 [1.40, 3.56]2.40-0.94 [-2.43, 0.45]3.60 [1.97, 4.87]32% [8%, 58%]56%72%+0.17+0.242026-08-06 → 2026-08-30
tmin00Znearest90d25 1 QC2.48 [1.26, 3.58]2.40-0.94 [-2.50, 0.66]3.60 [1.78, 4.87]32% [4%, 60%]56%72%+0.17+0.242026-08-06 → 2026-08-30
tmin00Znearest365d25 1 QC2.48 [1.26, 3.69]2.40-0.94 [-2.63, 0.88]3.60 [1.80, 4.89]32% [0%, 60%]56%72%+0.17+0.242026-08-06 → 2026-08-30
tmin00Znearestall25 1 QC2.48 [1.32, 3.59]2.40-0.94 [-2.61, 0.65]3.60 [1.84, 4.87]32% [0%, 59%]56%72%+0.17+0.242026-08-06 → 2026-08-30
tmin12Zbilinear30d25 1 QC2.65 [1.88, 3.38]2.67-0.16 [-1.44, 0.98]3.16 [2.38, 3.85]24% [5%, 48%]40%52%+0.12+0.152026-08-06 → 2026-08-30
tmin12Zbilinear90d25 1 QC2.65 [1.75, 3.41]2.67-0.16 [-1.33, 1.17]3.16 [2.30, 3.84]24% [0%, 50%]40%52%+0.12+0.152026-08-06 → 2026-08-30
tmin12Zbilinear365d25 1 QC2.65 [1.66, 3.48]2.67-0.16 [-1.55, 1.34]3.16 [2.20, 3.96]24% [0%, 50%]40%52%+0.12+0.152026-08-06 → 2026-08-30
tmin12Zbilinearall25 1 QC2.65 [1.69, 3.45]2.67-0.16 [-1.53, 1.26]3.16 [2.25, 3.91]24% [0%, 50%]40%52%+0.12+0.152026-08-06 → 2026-08-30
tmin12Znearest30d25 1 QC2.76 [2.00, 3.53]2.60-0.90 [-2.04, 0.21]3.23 [2.43, 3.95]16% [0%, 36%]40%52%+0.08+0.182026-08-06 → 2026-08-30
tmin12Znearest90d25 1 QC2.76 [1.87, 3.51]2.60-0.90 [-2.01, 0.37]3.23 [2.30, 3.93]16% [0%, 42%]40%52%+0.08+0.182026-08-06 → 2026-08-30
tmin12Znearest365d25 1 QC2.76 [1.79, 3.65]2.60-0.90 [-2.19, 0.50]3.23 [2.19, 4.05]16% [0%, 43%]40%52%+0.08+0.182026-08-06 → 2026-08-30
tmin12Znearestall25 1 QC2.76 [1.84, 3.62]2.60-0.90 [-2.19, 0.41]3.23 [2.26, 3.99]16% [0%, 42%]40%52%+0.08+0.182026-08-06 → 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 NCEP GFS at KPHL, lead day 5, 00Z bilinear tmax+20+100-10-202026-08-06: -4.08 °F2026-08-07: +0.76 °F2026-08-08: +1.18 °F2026-08-09: +0.02 °F2026-08-10: +1.88 °F2026-08-11: +4.84 °F2026-08-12: -9.83 °F2026-08-13: -2.55 °F2026-08-14: -13.1 °F2026-08-15: -7.18 °F2026-08-16: +5.08 °F2026-08-17: -5.39 °F2026-08-18: -3.88 °F2026-08-19: -2.83 °F2026-08-20: -0.22 °F2026-08-21: -12.34 °F2026-08-22: -6.52 °F2026-08-23: -5.63 °F2026-08-24: +0.2 °F2026-08-25: -0.75 °F2026-08-26: +1.27 °F2026-08-27: +5.73 °F2026-08-28: -0.32 °F2026-08-29: +8.59 °F2026-08-30: -4.05 °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
2026-08-30-4.05
2026-08-29+8.59
2026-08-28-0.32
2026-08-27+5.73
2026-08-26+1.27
2026-08-25-0.75
2026-08-24+0.20
2026-08-23-5.63
2026-08-22-6.52
2026-08-21-12.34
2026-08-20-0.22
2026-08-19-2.83
2026-08-18-3.88
2026-08-17-5.39
2026-08-16+5.08
2026-08-15-7.18
2026-08-14-13.10
2026-08-13-2.55
2026-08-12-9.83
2026-08-11+4.84
2026-08-10+1.88
2026-08-09+0.02
2026-08-08+1.18
2026-08-07+0.76
2026-08-06-4.08

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KPHL, 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: 2 days-12 to -10 °F: 0 days-10 to -8 °F: 1 day-8 to -6 °F: 2 days-6 to -4 °F: 4 days-4 to -2 °F: 3 days-2 to 0 °F: 3 days0 to 2 °F: 6 days2 to 4 °F: 0 days4 to 6 °F: 3 days6 to 8 °F: 0 days8 to 10 °F: 1 day10 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| 4.05 · P90 |e| 9.33 °F-200+20 °Fn = 25 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
-14.00-12.002
-12.00-10.000
-10.00-8.001
-8.00-6.002
-6.00-4.004
-4.00-2.003
-2.00+0.003
+0.00+2.006
+2.00+4.000
+4.00+6.003
+6.00+8.000
+8.00+10.001
+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
2026-08254.33 -1.96

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-06 → 2026-08-30 25
NCEP GFS2026-08-06 → 2026-08-30 25
NCEP GFS2026-08-06 → 2026-08-30 25
NCEP GFS2026-08-06 → 2026-08-30 25

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 25 +1.38 [-0.06, 2.62] no
GraphCast (IFS init) 25 -0.16 [-1.76, 1.02] no
ECMWF IFS HRES 18 +0.85 [-0.91, 2.16] no
Persistence (baseline) 25 +0.65 [-1.13, 2.44] no

Cite this page

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

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KPHL (Philadelphia Intl), model gfs, 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/KPHL/model/gfs/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