Chicago, Illinois Revisions
MILEPOST 1481
Chicago's forecast for Wednesday has moved 8°F warmer
61°F in the 20261021T12:00Z run, 69°F in the 20261023T06:00Z — the largest revision of any city on the roster. The current run's 10th-to-90th percentile spread at that hour is 11°F.
Successive cycles do not merely refresh a forecast; they leave a trail. For Wednesday, October 28 at 21Z in Chicago, that trail runs from 60.5°F in the 20261021T12:00Z cycle to 68.6°F in the 20261023T06:00Z — a move of +8.1°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 Wednesday at 21Z api.weather.city /v1/history (nbm-qmd) |
8.1 °F | normal 0.0 °F · 1 of 7 8 synoptic cycles |
| 10th-to-90th percentile spread at that hour api.weather.city (nbm-qmd) |
10.7 °F | normal 8.1 °F current run |
- Milepost
- 1481 · laid 2026-10-23T16:25:20Z
- Model
- nbm-qmd · cycle 20261023T06:00Z
- 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
- d4de5d6b54621043d0ae91a3a3973b52e7020c5d92f0402deadd71e47e40deed
- Machine
- JSON