Edition 2026-09-18 The Ledger Archive API RSS Weather Trader
Milepost
1131

TheForecast Post

A chronicle of American weather and climate  ·  Friday, 18 September 2026

Nashville, Tennessee Revisions MILEPOST 1131

Nashville's forecast for Wednesday has moved 9°F colder

88°F in the 20260916T12:00Z run, 79°F in the 20260918T06:00Z — the 2nd-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 15°F.

Successive cycles do not merely refresh a forecast; they leave a trail. For Wednesday, September 23 at 18Z in Nashville, that trail runs from 88.5°F in the 20260916T12:00Z cycle to 79.5°F in the 20260918T06:00Z — a move of -9.0°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 Wednesday at 18Z
api.weather.city /v1/history (nbm-qmd)
-9 °F normal 0.0 °F · 2 of 6
8 synoptic cycles
10th-to-90th percentile spread at that hour
api.weather.city (nbm-qmd)
14.7 °F normal 9.0 °F
current run
Milepost
1131 · laid 2026-09-18T16:25:18Z
Model
nbm-qmd · cycle 20260918T06:00Z
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
645ae8ec23cde1ce2a497d2a95092c243e1ab03778fb7692c092660bef901fa9
Machine
JSON