Edition 2026-09-29 The Ledger Archive API RSS Weather Trader
Milepost
1243

TheForecast Post

A chronicle of American weather and climate  ·  Tuesday, 29 September 2026

Denver, Colorado Revisions MILEPOST 1243

Denver's forecast for Wednesday has moved 8°F colder

68°F in the 20260927T06:00Z run, 60°F in the 20260929T00:00Z — the 3rd-largest revision of the 6 cities on the roster that moved at all. The current run's 10th-to-90th percentile spread at that hour is 12°F.

Successive cycles do not merely refresh a forecast; they leave a trail. For Wednesday, September 30 at 21Z in Denver, that trail runs from 67.7°F in the 20260927T06:00Z cycle to 59.8°F in the 20260929T00:00Z — a move of -7.9°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 Wednesday at 21Z
api.weather.city /v1/history (nbm-qmd)
-7.9 °F normal 0.0 °F · 3 of 6
8 synoptic cycles
10th-to-90th percentile spread at that hour
api.weather.city (nbm-qmd)
12.1 °F normal 7.9 °F
current run
Milepost
1243 · laid 2026-09-29T10:25:14Z
Model
nbm-qmd · cycle 20260929T00:00Z
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
3d1670abe9a7a91460e69fd3b6e84c238c45dd4f565bc710acc61d49a847136a
Machine
JSON