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

Las Vegas Harry Reid · GraphCast (IFS init) · lead day 4

KLAS · graphcast_ifs · lead 4

Target day = initialization date + 4 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
tmax00Zbilinear30d25 1 QC7.23 [6.21, 8.16]2.82-6.58 [-8.05, -4.95]7.72 [6.80, 8.45]4% [0%, 11%]4%8%-0.27+0.502026-08-05 → 2026-08-29
tmax00Zbilinear90d25 1 QC7.23 [6.05, 8.29]2.82-6.58 [-8.28, -4.87]7.72 [6.63, 8.57]4% [0%, 12%]4%8%-0.27+0.502026-08-05 → 2026-08-29
tmax00Zbilinear365d31 1 QC6.26 [4.13, 7.90]3.11-5.74 [-7.74, -3.70]7.05 [5.11, 8.26]10% [0%, 24%]13%23%-0.08+0.462026-01-05 → 2026-08-29
tmax00Zbilinearall31 1 QC6.26 [3.71, 7.74]3.11-5.74 [-7.65, -3.36]7.05 [4.70, 8.12]10% [0%, 25%]13%23%-0.08+0.462026-01-05 → 2026-08-29
tmax00Znearest30d25 1 QC8.33 [7.29, 9.26]2.74-7.77 [-9.19, -6.16]8.74 [7.80, 9.49]0% [0%, 0%]4%4%-0.47+0.512026-08-05 → 2026-08-29
tmax00Znearest90d25 1 QC8.33 [7.19, 9.32]2.74-7.77 [-9.31, -6.05]8.74 [7.67, 9.56]0% [0%, 0%]4%4%-0.47+0.512026-08-05 → 2026-08-29
tmax00Znearest365d31 1 QC7.34 [5.18, 9.03]3.10-6.89 [-8.91, -4.81]8.01 [5.99, 9.32]0% [0%, 0%]10%13%-0.26+0.462026-01-05 → 2026-08-29
tmax00Znearestall31 1 QC7.34 [4.74, 8.89]3.10-6.89 [-8.79, -4.45]8.01 [5.60, 9.19]0% [0%, 0%]10%13%-0.26+0.462026-01-05 → 2026-08-29
tmax12Zbilinear30d25 1 QC7.06 [5.98, 7.78]2.25-6.82 [-7.73, -5.68]7.51 [6.55, 8.06]0% [0%, 0%]4%8%-0.24+0.602026-08-05 → 2026-08-29
tmax12Zbilinear90d25 1 QC7.06 [5.85, 7.86]2.25-6.82 [-7.86, -5.50]7.51 [6.44, 8.06]0% [0%, 0%]4%8%-0.24+0.602026-08-05 → 2026-08-29
tmax12Zbilinear365d30 1 QC6.34 [4.43, 7.60]2.56-6.14 [-7.48, -4.39]6.97 [5.12, 7.89]3% [0%, 12%]10%13%-0.08+0.572026-01-05 → 2026-08-29
tmax12Zbilinearall30 1 QC6.34 [4.06, 7.58]2.56-6.14 [-7.42, -4.01]6.97 [4.60, 7.87]3% [0%, 14%]10%13%-0.08+0.572026-01-05 → 2026-08-29
tmax12Znearest30d25 1 QC8.02 [6.88, 8.80]2.31-7.86 [-8.75, -6.65]8.47 [7.49, 9.06]0% [0%, 0%]0%12%-0.41+0.592026-08-05 → 2026-08-29
tmax12Znearest90d25 1 QC8.02 [6.78, 8.86]2.31-7.86 [-8.86, -6.50]8.47 [7.37, 9.10]0% [0%, 0%]0%12%-0.41+0.592026-08-05 → 2026-08-29
tmax12Znearest365d30 1 QC7.31 [5.43, 8.60]2.59-7.17 [-8.53, -5.35]7.91 [6.03, 8.91]0% [0%, 0%]3%17%-0.24+0.562026-01-05 → 2026-08-29
tmax12Znearestall30 1 QC7.31 [4.98, 8.62]2.59-7.17 [-8.53, -4.95]7.91 [5.48, 8.85]0% [0%, 0%]3%17%-0.24+0.562026-01-05 → 2026-08-29
tmin00Zbilinear30d25 1 QC3.95 [3.12, 4.86]2.20-3.11 [-4.86, -0.95]4.33 [3.53, 5.14]8% [0%, 19%]12%28%+0.32+0.622026-08-05 → 2026-08-29
tmin00Zbilinear90d25 1 QC3.95 [3.10, 5.10]2.20-3.11 [-5.10, -1.00]4.33 [3.48, 5.33]8% [0%, 18%]12%28%+0.32+0.622026-08-05 → 2026-08-29
tmin00Zbilinear365d31 1 QC3.45 [2.32, 4.61]2.76-2.26 [-4.54, -0.12]3.98 [2.91, 4.93]16% [0%, 34%]23%39%+0.39+0.512026-01-05 → 2026-08-29
tmin00Zbilinearall31 1 QC3.45 [2.26, 4.65]2.76-2.26 [-4.42, 0.01]3.98 [2.87, 4.97]16% [0%, 38%]23%39%+0.39+0.512026-01-05 → 2026-08-29
tmin00Znearest30d25 1 QC4.75 [3.51, 5.95]2.19-4.27 [-5.95, -2.17]5.21 [4.10, 6.18]8% [0%, 20%]12%16%+0.18+0.622026-08-05 → 2026-08-29
tmin00Znearest90d25 1 QC4.75 [3.50, 6.17]2.19-4.27 [-6.17, -2.25]5.21 [4.10, 6.37]8% [0%, 20%]12%16%+0.18+0.622026-08-05 → 2026-08-29
tmin00Znearest365d31 1 QC4.05 [2.46, 5.65]2.81-3.37 [-5.60, -1.15]4.72 [3.24, 5.95]16% [0%, 33%]26%29%+0.28+0.502026-01-05 → 2026-08-29
tmin00Znearestall31 1 QC4.05 [2.37, 5.66]2.81-3.37 [-5.50, -1.07]4.72 [3.14, 5.99]16% [0%, 37%]26%29%+0.28+0.502026-01-05 → 2026-08-29
tmin12Zbilinear30d25 1 QC3.79 [2.87, 4.63]1.85-3.50 [-4.63, -2.10]4.21 [3.35, 4.88]8% [0%, 21%]20%36%+0.35+0.682026-08-05 → 2026-08-29
tmin12Zbilinear90d25 1 QC3.79 [2.90, 4.68]1.85-3.50 [-4.68, -2.13]4.21 [3.37, 4.98]8% [0%, 21%]20%36%+0.35+0.682026-08-05 → 2026-08-29
tmin12Zbilinear365d30 1 QC3.39 [2.30, 4.42]2.29-2.79 [-4.40, -0.96]3.90 [2.87, 4.78]17% [0%, 38%]30%43%+0.38+0.582026-01-05 → 2026-08-29
tmin12Zbilinearall30 1 QC3.39 [2.15, 4.44]2.29-2.79 [-4.43, -0.93]3.90 [2.72, 4.79]17% [0%, 44%]30%43%+0.38+0.582026-01-05 → 2026-08-29
tmin12Znearest30d25 1 QC4.62 [3.44, 5.62]1.87-4.47 [-5.62, -3.07]5.05 [4.03, 5.86]4% [0%, 12%]16%20%+0.20+0.682026-08-05 → 2026-08-29
tmin12Znearest90d25 1 QC4.62 [3.48, 5.67]1.87-4.47 [-5.67, -3.09]5.05 [4.06, 5.92]4% [0%, 12%]16%20%+0.20+0.682026-08-05 → 2026-08-29
tmin12Znearest365d30 1 QC4.08 [2.70, 5.42]2.28-3.75 [-5.42, -1.89]4.65 [3.31, 5.69]10% [0%, 25%]27%33%+0.25+0.582026-01-05 → 2026-08-29
tmin12Znearestall30 1 QC4.08 [2.58, 5.41]2.28-3.75 [-5.39, -1.82]4.65 [3.20, 5.70]10% [0%, 26%]27%33%+0.25+0.582026-01-05 → 2026-08-29

+ 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 4, 00Z bilinear tmax+20+100-10-202026-08-05: -7.85 °F2026-08-06: -4.45 °F2026-08-07: -2.36 °F2026-08-08: -8.45 °F2026-08-09: -8.85 °F2026-08-10: -6.08 °F2026-08-11: -3.86 °F2026-08-12: -11.82 °F2026-08-13: -0.64 °F2026-08-14: -7.93 °F2026-08-15: +8.1 °F2026-08-16: -5.02 °F2026-08-17: -7.69 °F2026-08-18: -7.96 °F2026-08-19: -6.16 °F2026-08-20: -9.37 °F2026-08-21: -10.74 °F2026-08-22: -10.99 °F2026-08-23: -8.95 °F2026-08-24: -6.51 °F2026-08-25: -6.18 °F2026-08-26: -5.42 °F2026-08-27: -8.75 °F2026-08-28: -11.41 °F2026-08-29: -5.16 °F2026-08-052026-08-29°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
2026-08-29-5.16
2026-08-28-11.41
2026-08-27-8.75
2026-08-26-5.42
2026-08-25-6.18
2026-08-24-6.51
2026-08-23-8.95
2026-08-22-10.99
2026-08-21-10.74
2026-08-20-9.37
2026-08-19-6.16
2026-08-18-7.96
2026-08-17-7.69
2026-08-16-5.02
2026-08-15+8.10
2026-08-14-7.93
2026-08-13-0.64
2026-08-12-11.82
2026-08-11-3.86
2026-08-10-6.08
2026-08-09-8.85
2026-08-08-8.45
2026-08-07-2.36
2026-08-06-4.45
2026-08-05-7.85

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KLAS, lead day 4-20 to -18 °F: 0 days-18 to -16 °F: 0 days-16 to -14 °F: 0 days-14 to -12 °F: 0 days-12 to -10 °F: 4 days-10 to -8 °F: 5 days-8 to -6 °F: 8 days-6 to -4 °F: 5 days-4 to -2 °F: 4 days-2 to 0 °F: 4 days0 to 2 °F: 0 days2 to 4 °F: 0 days4 to 6 °F: 0 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| 6.18 · P90 |e| 10.74 °F-200+20 °Fn = 31 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
-14.00-12.000
-12.00-10.004
-10.00-8.005
-8.00-6.008
-6.00-4.005
-4.00-2.004
-2.00+0.004
+0.00+2.000
+2.00+4.000
+4.00+6.000
+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
2026-08257.23 -6.58
2026-0162.24 -2.24

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-05 → 2026-08-29 31
GraphCast (IFS init)2026-01-05 → 2026-08-29 31
GraphCast (IFS init)2026-01-05 → 2026-08-29 30
GraphCast (IFS init)2026-01-05 → 2026-08-29 30

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 25 +1.32 [0.74, 1.92] yes
NCEP GFS 25 +2.69 [1.89, 3.36] yes
ECMWF IFS HRES 19 +4.06 [2.31, 5.35] yes
Persistence (baseline) 25 +1.55 [-2.73, 6.22] no

Cite this page

ShortCastCheck, KLAS graphcast_ifs lead 4, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KLAS/model/graphcast_ifs/lead/4/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KLAS (Las Vegas Harry Reid), model graphcast_ifs, lead day 4. 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/4/

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