Chicago, Illinois Revisions
MILEPOST 1260
Chicago's forecast for Sunday has moved 10°F warmer
56°F in the 20260929T12:00Z run, 66°F in the 20261001T00:00Z — 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 19°F.
Successive cycles do not merely refresh a forecast; they leave a trail. For Sunday, October 11 at 00Z in Chicago, that trail runs from 56.4°F in the 20260929T12:00Z cycle to 66.3°F in the 20261001T00:00Z — a move of +9.9°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 00Z api.weather.city /v1/history (nbm-qmd) |
9.9 °F | normal 0.0 °F · 3 of 9 8 synoptic cycles |
| 10th-to-90th percentile spread at that hour api.weather.city (nbm-qmd) |
18.7 °F | normal 9.9 °F current run |
- Milepost
- 1260 · laid 2026-10-01T10:25:12Z
- Model
- nbm-qmd · cycle 20261001T00:00Z
- 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
- 129ecaeaef44c97c315254e7af9a85107913a37fc5340d264aafd39f927e9635
- Machine
- JSON