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

New York, New York Revisions MILEPOST 1100

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

70°F in the 20260913T18:00Z run, 62°F in the 20260915T12:00Z — 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 9°F.

Successive cycles do not merely refresh a forecast; they leave a trail. For Saturday, September 19 at 12Z in New York, that trail runs from 70.2°F in the 20260913T18:00Z cycle to 62.4°F in the 20260915T12:00Z — a move of -7.8°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 Saturday at 12Z
api.weather.city /v1/history (nbm-qmd)
-7.8 °F normal 0.0 °F · 3 of 6
8 synoptic cycles
10th-to-90th percentile spread at that hour
api.weather.city (nbm-qmd)
9.4 °F normal 7.8 °F
current run
Milepost
1100 · laid 2026-09-15T22:25:16Z
Model
nbm-qmd · cycle 20260915T12:00Z
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
32beffce21cc6b7d425b18bc8f402975d3fe430998b9b78906c8cc1b3597c456
Machine
JSON