Chicago, Illinois Revisions
MILEPOST 1530
Chicago's forecast for Thursday has moved 7°F warmer
48°F in the 20261027T18:00Z run, 55°F in the 20261029T12:00Z — the 3rd-largest revision of the 5 cities on the roster that moved at all. The current run's 10th-to-90th percentile spread at that hour is 12°F.
Successive cycles do not merely refresh a forecast; they leave a trail. For Thursday, November 5 at 12Z in Chicago, that trail runs from 47.6°F in the 20261027T18:00Z cycle to 54.6°F in the 20261029T12:00Z — a move of +7.0°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 Thursday at 12Z api.weather.city /v1/history (nbm-qmd) |
7 °F | normal 0.0 °F · 3 of 5 8 synoptic cycles |
| 10th-to-90th percentile spread at that hour api.weather.city (nbm-qmd) |
11.7 °F | normal 7.0 °F current run |
- Milepost
- 1530 · laid 2026-10-29T22:25:23Z
- Model
- nbm-qmd · cycle 20261029T12:00Z
- 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
- 4a985d916639a676379ca89b3229a12e6e473cca2cb6c0fac21ef31c857694f7
- Machine
- JSON