Edition 2026-09-22 The Ledger Archive API RSS Weather Trader
Milepost
1181

TheForecast Post

A chronicle of American weather and climate  ·  Tuesday, 22 September 2026

Denver, Colorado Revisions MILEPOST 1180

Denver's forecast for Thursday has moved 12°F colder

78°F in the 20260920T18:00Z run, 66°F in the 20260922T12:00Z — the largest revision of any city on the roster. The current run's 10th-to-90th percentile spread at that hour is 14°F.

Successive cycles do not merely refresh a forecast; they leave a trail. For Thursday, September 24 at 21Z in Denver, that trail runs from 77.9°F in the 20260920T18:00Z cycle to 65.9°F in the 20260922T12:00Z — a move of -12.0°F across 8 runs.

The change is about half the run's 10th-to-90th percentile spread, so the earlier forecast is still inside the current range of outcomes.

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 Thursday at 21Z
api.weather.city /v1/history (nbm-qmd)
-12 °F normal 0.0 °F · 1 of 4
8 synoptic cycles
10th-to-90th percentile spread at that hour
api.weather.city (nbm-qmd)
13.9 °F normal 12.0 °F
current run
Milepost
1180 · laid 2026-09-22T22:25:12Z
Model
nbm-qmd · cycle 20260922T12:00Z
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
b1333a56845bd4ee1a42bc160208252c1c8f6c82fb77f04466ea80c45394633c
Machine
JSON