Chicago, Illinois Revisions
MILEPOST 1492
Chicago's forecast for Friday has moved 12°F warmer
60°F in the 20261022T18:00Z run, 72°F in the 20261024T12:00Z — the 2nd-largest revision of the 5 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 Friday, October 30 at 21Z in Chicago, that trail runs from 59.7°F in the 20261022T18:00Z cycle to 72.0°F in the 20261024T12:00Z — a move of +12.3°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 Friday at 21Z api.weather.city /v1/history (nbm-qmd) |
12.3 °F | normal 0.0 °F · 2 of 5 8 synoptic cycles |
| 10th-to-90th percentile spread at that hour api.weather.city (nbm-qmd) |
7.7 °F | normal 12.3 °F current run |
- Milepost
- 1492 · laid 2026-10-24T22:25:22Z
- Model
- nbm-qmd · cycle 20261024T12:00Z
- 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
- 284f3c9d208f6b75353e7c4496ab26355441e5b1cdf77784321a9a29dc7827c0
- Machine
- JSON