Chicago, Illinois Revisions
MILEPOST 1309
Chicago's forecast for Saturday has moved 9°F warmer
67°F in the 20261004T18:00Z run, 76°F in the 20261006T12:00Z — the 3rd-largest revision of the 9 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, October 10 at 21Z in Chicago, that trail runs from 67.4°F in the 20261004T18:00Z cycle to 76.4°F in the 20261006T12:00Z — a move of +9.0°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 21Z api.weather.city /v1/history (nbm-qmd) |
9 °F | normal 0.0 °F · 3 of 9 8 synoptic cycles |
| 10th-to-90th percentile spread at that hour api.weather.city (nbm-qmd) |
7.7 °F | normal 9.0 °F current run |
- Milepost
- 1309 · laid 2026-10-06T22:25:14Z
- Model
- nbm-qmd · cycle 20261006T12:00Z
- 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
- 0ccf0abded141802bf74b507ba8e55b5f15f39af31e4582eb3face723cc6dedd
- Machine
- JSON