Chicago, Illinois Revisions
MILEPOST 1483
Chicago's forecast for Wednesday has moved 10°F warmer
59°F in the 20261021T18:00Z run, 69°F in the 20261023T12:00Z — the largest revision of any city on the roster. The current run's 10th-to-90th percentile spread at that hour is 10°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 59.4°F in the 20261021T18:00Z cycle to 69.4°F in the 20261023T12:00Z — a move of +10.0°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 Wednesday at 21Z api.weather.city /v1/history (nbm-qmd) |
10 °F | normal 0.0 °F · 1 of 8 8 synoptic cycles |
| 10th-to-90th percentile spread at that hour api.weather.city (nbm-qmd) |
10.2 °F | normal 10.0 °F current run |
- Milepost
- 1483 · laid 2026-10-23T22:25:25Z
- Model
- nbm-qmd · cycle 20261023T12:00Z
- 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
- 0167e3a23f41b3ae1d612744b193011e301c590169526850e2a695f7d511df5a
- Machine
- JSON