Chicago, Illinois Revisions
MILEPOST 1579
Chicago's forecast for Friday has moved 6°F colder
53°F in the 20261102T12:00Z run, 46°F in the 20261104T06:00Z — the 2nd-largest revision of the 2 cities on the roster that moved at all. The current run's 10th-to-90th percentile spread at that hour is 7°F.
Successive cycles do not merely refresh a forecast; they leave a trail. For Friday, November 6 at 15Z in Chicago, that trail runs from 52.8°F in the 20261102T12:00Z cycle to 46.5°F in the 20261104T06:00Z — a move of -6.3°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 Friday at 15Z api.weather.city /v1/history (nbm-qmd) |
-6.3 °F | normal 0.0 °F · 2 of 2 8 synoptic cycles |
| 10th-to-90th percentile spread at that hour api.weather.city (nbm-qmd) |
6.6 °F | normal 6.3 °F current run |
- Milepost
- 1579 · laid 2026-11-04T16:25:25Z
- Model
- nbm-qmd · cycle 20261104T06:00Z
- 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
- 85c33a7d5c10f8a8f7214f58d9b997d713bcb7779abd989f645dab3852cf08c6
- Machine
- JSON