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Milepost
1253

TheForecast Post

A chronicle of American weather and climate  ·  Wednesday, 30 September 2026

Denver, Colorado Revisions MILEPOST 1251

Denver's forecast for Sunday has moved 10°F warmer

69°F in the 20260928T12:00Z run, 79°F in the 20260930T06:00Z — the largest revision of any city on the roster. The current run's 10th-to-90th percentile spread at that hour is 7°F.

Successive cycles do not merely refresh a forecast; they leave a trail. For Sunday, October 4 at 00Z in Denver, that trail runs from 68.9°F in the 20260928T12:00Z cycle to 78.8°F in the 20260930T06:00Z — a move of +10.0°F across 8 runs.

The change is larger than the run's own 10th-to-90th percentile spread — the guidance did not merely narrow, it moved off its previous position.

Model NBM-QMD, via api.weather.city /v1/history. Percentiles are the same run's own.

The numbers in this piece, with what they are measured against
forecast revision for Sunday at 00Z
api.weather.city /v1/history (nbm-qmd)
10 °F normal 0.0 °F · 1 of 5
8 synoptic cycles
10th-to-90th percentile spread at that hour
api.weather.city (nbm-qmd)
7.4 °F normal 10.0 °F
current run
Milepost
1251 · laid 2026-09-30T16:25:15Z
Model
nbm-qmd · cycle 20260930T06:00Z
Desk
revision v1
Method
the same valid time read from successive synoptic cycles; the move is last run minus first run
Source
https://api.weather.city/v1/history
Digest
11fc64f30fbcefc5142e96f8b50cce8547b913d45157ccc9aed0dd33cc731c09
Machine
JSON