Chicago, Illinois Revisions
MILEPOST 1564
Chicago's forecast for Saturday has moved 8°F colder
60°F in the 20261031T12:00Z run, 52°F in the 20261102T06:00Z — 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 8°F.
Successive cycles do not merely refresh a forecast; they leave a trail. For Saturday, November 7 at 18Z in Chicago, that trail runs from 59.7°F in the 20261031T12:00Z cycle to 51.7°F in the 20261102T06:00Z — a move of -8.1°F across 8 runs.
The change is larger than the run's own 10th-to-90th percentile spread — the guidance did not merely narrow, it moved off its previous position.
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 Saturday at 18Z api.weather.city /v1/history (nbm-qmd) |
-8.1 °F | normal 0.0 °F · 3 of 7 8 synoptic cycles |
| 10th-to-90th percentile spread at that hour api.weather.city (nbm-qmd) |
7.8 °F | normal 8.1 °F current run |
- Milepost
- 1564 · laid 2026-11-02T16:25:25Z
- Model
- nbm-qmd · cycle 20261102T06:00Z
- 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
- 324546e985bfb3b1c5e92945e1a910b1e1d8b35ddd2ce5593dd40e3965c6c20e
- Machine
- JSON