Chicago, Illinois Revisions
MILEPOST 1558
Chicago's forecast for Friday has moved 7°F colder
59°F in the 20261030T12:00Z run, 51°F in the 20261101T06:00Z — 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 8°F.
Successive cycles do not merely refresh a forecast; they leave a trail. For Friday, November 6 at 21Z in Chicago, that trail runs from 58.8°F in the 20261030T12:00Z cycle to 51.4°F in the 20261101T06:00Z — a move of -7.4°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 21Z api.weather.city /v1/history (nbm-qmd) |
-7.4 °F | normal 0.0 °F · 3 of 9 8 synoptic cycles |
| 10th-to-90th percentile spread at that hour api.weather.city (nbm-qmd) |
7.7 °F | normal 7.4 °F current run |
- Milepost
- 1558 · laid 2026-11-01T16:25:23Z
- Model
- nbm-qmd · cycle 20261101T06:00Z
- 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
- a8d5322176a11d8ac123b5e5713dd53b00a444416a7d6ebb61f5aeb74d1fec37
- Machine
- JSON