Edition 2026-09-16 The Ledger Archive API RSS Weather Trader
Milepost
1108

TheForecast Post

A chronicle of American weather and climate  ·  Wednesday, 16 September 2026

Denver, Colorado Revisions MILEPOST 1089

Denver's forecast for Sunday has moved 9°F colder

78°F in the 20260912T18:00Z run, 69°F in the 20260914T18:00Z — the 3rd-largest revision of the 9 cities on the roster that moved at all. The current run's 10th-to-90th percentile spread at that hour is 11°F.

Successive cycles do not merely refresh a forecast; they leave a trail. For Sunday, September 20 at 18Z in Denver, that trail runs from 78.2°F in the 20260912T18:00Z cycle to 68.8°F in the 20260914T18:00Z — a move of -9.4°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 Sunday at 18Z
api.weather.city /v1/history (nbm-qmd)
-9.4 °F normal 0.0 °F · 3 of 9
8 synoptic cycles
10th-to-90th percentile spread at that hour
api.weather.city (nbm-qmd)
11.4 °F normal 9.4 °F
current run
Milepost
1089 · laid 2026-09-15T04:25:13Z
Model
nbm-qmd · cycle 20260914T18:00Z
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
cf6052156042e06b19e5708692b4e88d0aa5c07d3d3087e19d428bae6cc79a5a
Machine
JSON