Chicago, Illinois Revisions
MILEPOST 1267
Chicago's forecast for Monday has moved 9°F warmer
56°F in the 20260930T12:00Z run, 65°F in the 20261001T18:00Z — the 3rd-largest revision of the 7 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 Monday, October 12 at 00Z in Chicago, that trail runs from 55.9°F in the 20260930T12:00Z cycle to 65.0°F in the 20261001T18:00Z — a move of +9.1°F across 8 runs.
The change sits well inside the run's own spread, which is the guidance converging rather than reversing.
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 Monday at 00Z api.weather.city /v1/history (nbm-qmd) |
9.1 °F | normal 0.0 °F · 3 of 7 8 synoptic cycles |
| 10th-to-90th percentile spread at that hour api.weather.city (nbm-qmd) |
19.3 °F | normal 9.1 °F current run |
- Milepost
- 1267 · laid 2026-10-02T04:25:12Z
- Model
- nbm-qmd · cycle 20261001T18:00Z
- 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
- 25db3909dbabcc01a001c62e7dc749bf92b6d47399b998a470e1345cd99c3783
- Machine
- JSON