Chicago, Illinois Revisions
MILEPOST 1349
Chicago's forecast for Tuesday has moved 12°F warmer
63°F in the 20261008T18:00Z run, 75°F in the 20261010T12:00Z — the 2nd-largest revision of the 8 cities on the roster that moved at all. The current run's 10th-to-90th percentile spread at that hour is 16°F.
Successive cycles do not merely refresh a forecast; they leave a trail. For Tuesday, October 13 at 21Z in Chicago, that trail runs from 63.0°F in the 20261008T18:00Z cycle to 75.1°F in the 20261010T12:00Z — a move of +12.1°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 Tuesday at 21Z api.weather.city /v1/history (nbm-qmd) |
12.1 °F | normal 0.0 °F · 2 of 8 8 synoptic cycles |
| 10th-to-90th percentile spread at that hour api.weather.city (nbm-qmd) |
16.2 °F | normal 12.1 °F current run |
- Milepost
- 1349 · laid 2026-10-10T22:25:13Z
- Model
- nbm-qmd · cycle 20261010T12:00Z
- 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
- dd750999a67108d9e382915771066287c78cdaf87f6c2d35ff9dd8eae0f254e7
- Machine
- JSON