Chicago, Illinois Revisions
MILEPOST 1352
Chicago's forecast for Tuesday has moved 13°F warmer
64°F in the 20261009T00:00Z run, 77°F in the 20261010T18:00Z — the largest revision of any city on the roster. The current run's 10th-to-90th percentile spread at that hour is 10°F.
Successive cycles do not merely refresh a forecast; they leave a trail. For Tuesday, October 13 at 18Z in Chicago, that trail runs from 64.2°F in the 20261009T00:00Z cycle to 77.5°F in the 20261010T18:00Z — a move of +13.2°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 Tuesday at 18Z api.weather.city /v1/history (nbm-qmd) |
13.2 °F | normal 0.0 °F · 1 of 10 8 synoptic cycles |
| 10th-to-90th percentile spread at that hour api.weather.city (nbm-qmd) |
10.3 °F | normal 13.2 °F current run |
- Milepost
- 1352 · laid 2026-10-11T04:25:15Z
- Model
- nbm-qmd · cycle 20261010T18:00Z
- 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
- 6501b003630b76bae2786b4d820b19c6217ef8786c5e18a0962555183304a825
- Machine
- JSON