Edition 2026-09-19 The Ledger Archive API RSS Weather Trader
Milepost
1137

TheForecast Post

A chronicle of American weather and climate  ·  Saturday, 19 September 2026

Nashville, Tennessee Revisions MILEPOST 1137

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

68°F in the 20260917T00:00Z run, 59°F in the 20260918T18:00Z — the 2nd-largest revision of the 8 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, September 27 at 12Z in Nashville, that trail runs from 68.3°F in the 20260917T00:00Z cycle to 59.2°F in the 20260918T18:00Z — a move of -9.1°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 12Z
api.weather.city /v1/history (nbm-qmd)
-9.1 °F normal 0.0 °F · 2 of 8
8 synoptic cycles
10th-to-90th percentile spread at that hour
api.weather.city (nbm-qmd)
17.1 °F normal 9.1 °F
current run
Milepost
1137 · laid 2026-09-19T04:25:25Z
Model
nbm-qmd · cycle 20260918T18:00Z
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
44f8807c496722150d5c925f89ede246527e507fcc8807d68ef568ac5651b4e2
Machine
JSON