Chicago, Illinois Revisions
MILEPOST 1269
Chicago's forecast for Sunday has moved 11°F warmer
60°F in the 20260930T06:00Z run, 71°F in the 20261002T00:00Z — the 2nd-largest revision of the 9 cities on the roster that moved at all. The current run's 10th-to-90th percentile spread at that hour is 19°F.
Successive cycles do not merely refresh a forecast; they leave a trail. For Sunday, October 11 at 18Z in Chicago, that trail runs from 59.8°F in the 20260930T06:00Z cycle to 71.1°F in the 20261002T00:00Z — a move of +11.2°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) |
11.2 °F | normal 0.0 °F · 2 of 9 8 synoptic cycles |
| 10th-to-90th percentile spread at that hour api.weather.city (nbm-qmd) |
18.9 °F | normal 11.2 °F current run |
- Milepost
- 1269 · laid 2026-10-02T10:25:11Z
- Model
- nbm-qmd · cycle 20261002T00:00Z
- 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
- df4f3385176ddcd2a141020498e30a2945ef01f27e0d18e3c9bc8977a9b797e2
- Machine
- JSON