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

Las Vegas Harry Reid · GraphCast (IFS init) · lead day 0

KLAS · graphcast_ifs · lead 0

Target day = initialization date + 0 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, 2 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 2 QC5.17 [4.59, 5.86]1.43-4.94 [-5.46, -4.48]5.55 [4.71, 6.53]0% [0%, 0%]0%4%——2026-08-01 → 2026-08-30
tmax00Zbilinear90d28 2 QC5.17 [4.52, 5.82]1.43-4.94 [-5.51, -4.44]5.55 [4.66, 6.47]0% [0%, 0%]0%4%——2026-08-01 → 2026-08-30
tmax00Zbilinear365d34 2 QC5.08 [4.54, 5.68]1.40-4.89 [-5.35, -4.44]5.43 [4.69, 6.29]0% [0%, 0%]0%6%——2026-01-01 → 2026-08-30
tmax00Zbilinearall34 2 QC5.08 [4.51, 5.73]1.40-4.89 [-5.46, -4.45]5.43 [4.65, 6.30]0% [0%, 0%]0%6%——2026-01-01 → 2026-08-30
tmax00Znearest30d28 2 QC6.46 [6.03, 6.95]1.44-6.33 [-6.84, -5.86]6.79 [6.13, 7.55]0% [0%, 0%]4%4%——2026-08-01 → 2026-08-30
tmax00Znearest90d28 2 QC6.46 [5.97, 6.95]1.44-6.33 [-6.85, -5.82]6.79 [6.06, 7.54]0% [0%, 0%]4%4%——2026-08-01 → 2026-08-30
tmax00Znearest365d34 2 QC6.26 [5.71, 6.76]1.40-6.16 [-6.67, -5.63]6.57 [5.83, 7.30]0% [0%, 0%]3%3%——2026-01-01 → 2026-08-30
tmax00Znearestall34 2 QC6.26 [5.73, 6.83]1.40-6.16 [-6.74, -5.70]6.57 [5.83, 7.35]0% [0%, 0%]3%3%——2026-01-01 → 2026-08-30
tmin00Zbilinear30d28 2 QC2.40 [1.67, 3.13]1.61-1.83 [-3.11, -0.38]2.72 [1.90, 3.43]14% [3%, 30%]36%79%——2026-08-01 → 2026-08-30
tmin00Zbilinear90d28 2 QC2.40 [1.68, 3.28]1.61-1.83 [-3.27, -0.46]2.72 [1.94, 3.53]14% [0%, 30%]36%79%——2026-08-01 → 2026-08-30
tmin00Zbilinear365d34 2 QC2.26 [1.61, 2.97]1.74-1.44 [-2.78, -0.09]2.58 [1.84, 3.24]15% [2%, 29%]41%82%——2026-01-01 → 2026-08-30
tmin00Zbilinearall34 2 QC2.26 [1.66, 2.99]1.74-1.44 [-2.88, -0.20]2.58 [1.89, 3.28]15% [3%, 29%]41%82%——2026-01-01 → 2026-08-30
tmin00Znearest30d28 2 QC3.12 [2.05, 4.12]1.78-2.75 [-4.12, -1.17]3.50 [2.40, 4.37]11% [0%, 27%]29%39%——2026-08-01 → 2026-08-30
tmin00Znearest90d28 2 QC3.12 [2.11, 4.28]1.78-2.75 [-4.28, -1.21]3.50 [2.48, 4.47]11% [0%, 27%]29%39%——2026-08-01 → 2026-08-30
tmin00Znearest365d34 2 QC2.90 [1.94, 3.86]1.95-2.30 [-3.77, -0.78]3.28 [2.24, 4.15]12% [0%, 27%]32%50%——2026-01-01 → 2026-08-30
tmin00Znearestall34 2 QC2.90 [2.04, 3.95]1.95-2.30 [-3.89, -0.90]3.28 [2.38, 4.20]12% [0%, 26%]32%50%——2026-01-01 → 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 KLAS, lead day 0, 00Z bilinear tmax+20+100-10-202026-08-01: -5.34 °F2026-08-02: -3.56 °F2026-08-03: -4.97 °F2026-08-04: -4.12 °F2026-08-05: -6.14 °F2026-08-06: -2.12 °F2026-08-07: -4.32 °F2026-08-08: -5.58 °F2026-08-09: -5.6 °F2026-08-10: -3.49 °F2026-08-11: -4.09 °F2026-08-12: -10.62 °F2026-08-13: -4.42 °F2026-08-14: -12.36 °F2026-08-15: +3.22 °F2026-08-16: -4.62 °F2026-08-17: -5.27 °F2026-08-18: -4.78 °F2026-08-19: -4.22 °F2026-08-20: -5.67 °F2026-08-21: -5.11 °F2026-08-22: -3.99 °F2026-08-23: -5.05 °F2026-08-24: -6.55 °F2026-08-25: -5.26 °F2026-08-28: -5.35 °F2026-08-29: -5.31 °F2026-08-30: -3.7 °F2026-08-012026-08-30°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 (30 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-3.70
2026-08-29-5.31
2026-08-28-5.35
2026-08-27—
2026-08-26—
2026-08-25-5.26
2026-08-24-6.55
2026-08-23-5.05
2026-08-22-3.99
2026-08-21-5.11
2026-08-20-5.67
2026-08-19-4.22
2026-08-18-4.78
2026-08-17-5.27
2026-08-16-4.62
2026-08-15+3.22
2026-08-14-12.36
2026-08-13-4.42
2026-08-12-10.62
2026-08-11-4.09
2026-08-10-3.49
2026-08-09-5.60
2026-08-08-5.58
2026-08-07-4.32
2026-08-06-2.12
2026-08-05-6.14
2026-08-04-4.12
2026-08-03-4.97
2026-08-02-3.56
2026-08-01-5.34

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KLAS, lead day 0-20 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: 1 day-10 to -8 °F: 0 days-8 to -6 °F: 3 days-6 to -4 °F: 21 days-4 to -2 °F: 7 days-2 to 0 °F: 0 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| 4.88 · P90 |e| 6.42 °F-200+20 °Fn = 34 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
-12.00-10.001
-10.00-8.000
-8.00-6.003
-6.00-4.0021
-4.00-2.007
-2.00+0.000
+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
2026-08285.17 -4.94
2026-0164.63 -4.63

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-01 → 2026-08-30 34
GraphCast (IFS init)2026-01-01 → 2026-08-30 34

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 28 +0.14 [-0.26, 0.69] no
Aurora (GFS init) 2 -0.88 [-1.71, -0.05] yes
Aurora (IFS init) 3 +0.82 [0.53, 1.15] yes
FourCastNet v2 (GFS init) 2 -0.76 [-1.70, 0.19] no
FourCastNet v2 (IFS init) 3 -1.14 [-3.44, 0.61] no
NCEP GFS 28 +0.15 [-0.81, 1.12] no
GraphCast (GFS init) 2 -3.44 [-3.70, -3.18] yes
ECMWF IFS HRES 23 +1.43 [0.92, 2.06] yes
Pangu-Weather (GFS init) 2 -0.65 [-1.41, 0.11] no
Pangu-Weather (IFS init) 3 -0.53 [-1.07, 0.56] no

Cite this page

ShortCastCheck, KLAS graphcast_ifs lead 0, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KLAS/model/graphcast_ifs/lead/0/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KLAS (Las Vegas Harry Reid), model graphcast_ifs, lead day 0. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KLAS/model/graphcast_ifs/lead/0/

Accessed2026-08-31 (data through 2026-08-30; page built 2026-08-31T03:52:06+00:00)

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