Chicago, Illinois Revisions
MILEPOST 1324
Chicago's forecast for Sunday has moved 7°F colder
74°F in the 20261006T06:00Z run, 66°F in the 20261008T00:00Z — the 2nd-largest revision of the 6 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 Sunday, October 11 at 21Z in Chicago, that trail runs from 73.6°F in the 20261006T06:00Z cycle to 66.1°F in the 20261008T00:00Z — a move of -7.5°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 Sunday at 21Z api.weather.city /v1/history (nbm-qmd) |
-7.5 °F | normal 0.0 °F · 2 of 6 8 synoptic cycles |
| 10th-to-90th percentile spread at that hour api.weather.city (nbm-qmd) |
8.1 °F | normal 7.5 °F current run |
- Milepost
- 1324 · laid 2026-10-08T10:25:14Z
- Model
- nbm-qmd · cycle 20261008T00:00Z
- 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
- f516765a7f31b923a44a4c9889c63c9cb4077873a449de8ac9c4c00598eda99d
- Machine
- JSON