Edition 2026-09-27 The Ledger Archive API RSS Weather Trader
Milepost
1223

TheForecast Post

A chronicle of American weather and climate  ·  Sunday, 27 September 2026

Atlanta, Georgia Revisions MILEPOST 1223

Atlanta's forecast for Sunday has moved 12°F colder

85°F in the 20260925T00:00Z run, 73°F in the 20260926T18:00Z — the 2nd-largest revision of the 10 cities on the roster that moved at all. The current run's 10th-to-90th percentile spread at that hour is 17°F.

Successive cycles do not merely refresh a forecast; they leave a trail. For Sunday, October 4 at 18Z in Atlanta, that trail runs from 85.0°F in the 20260925T00:00Z cycle to 73.3°F in the 20260926T18:00Z — a move of -11.7°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)
-11.7 °F normal 0.0 °F · 2 of 10
8 synoptic cycles
10th-to-90th percentile spread at that hour
api.weather.city (nbm-qmd)
16.7 °F normal 11.7 °F
current run
Milepost
1223 · laid 2026-09-27T04:25:13Z
Model
nbm-qmd · cycle 20260926T18:00Z
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
bdb6cf29b586a7a9812b330e6df488b673972ad74adcd90526437e70784cb683
Machine
JSON