Edition 2026-09-22 The Ledger Archive API RSS Weather Trader
Milepost
1175

TheForecast Post

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

Denver, Colorado Revisions MILEPOST 1174

Denver's forecast for Thursday has moved 11°F colder

80°F in the 20260920T00:00Z run, 69°F in the 20260921T18:00Z — the largest revision of any city on the roster. The current run's 10th-to-90th percentile spread at that hour is 16°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 79.8°F in the 20260920T00:00Z cycle to 68.6°F in the 20260921T18:00Z — a move of -11.2°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)
-11.2 °F normal 0.0 °F · 1 of 5
8 synoptic cycles
10th-to-90th percentile spread at that hour
api.weather.city (nbm-qmd)
15.6 °F normal 11.2 °F
current run
Milepost
1174 · laid 2026-09-22T04:25:17Z
Model
nbm-qmd · cycle 20260921T18:00Z
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
eae7ff88c577f0d3d2247a4adc83f5f4072b31edec0099622b8b9fb7229e1651
Machine
JSON