Edition 2026-09-17 The Ledger Archive API RSS Weather Trader
Milepost
1113

TheForecast Post

A chronicle of American weather and climate  ·  Thursday, 17 September 2026

New York, New York Revisions MILEPOST 1113

New York's forecast for Sunday has moved 8°F colder

75°F in the 20260915T00:00Z run, 67°F in the 20260916T18:00Z — 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 14°F.

Successive cycles do not merely refresh a forecast; they leave a trail. For Sunday, September 20 at 18Z in New York, that trail runs from 75.1°F in the 20260915T00:00Z cycle to 66.8°F in the 20260916T18:00Z — a move of -8.3°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)
-8.3 °F normal 0.0 °F · 3 of 6
8 synoptic cycles
10th-to-90th percentile spread at that hour
api.weather.city (nbm-qmd)
13.6 °F normal 8.3 °F
current run
Milepost
1113 · laid 2026-09-17T04:25:20Z
Model
nbm-qmd · cycle 20260916T18:00Z
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
12e320a4138d76c1e5e94c7894197f660e3205b0d24ea91aacc81b8faabab40a
Machine
JSON