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Milepost
1160

TheForecast Post

A chronicle of American weather and climate  ·  Sunday, 20 September 2026

Minneapolis, Minnesota Revisions MILEPOST 1159

Minneapolis's forecast for Monday has moved 7°F colder

66°F in the 20260918T18:00Z run, 60°F in the 20260920T12:00Z — the 2nd-largest revision of the 3 cities on the roster that moved at all. 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 Monday, September 21 at 21Z in Minneapolis, that trail runs from 66.2°F in the 20260918T18:00Z cycle to 59.7°F in the 20260920T12:00Z — a move of -6.5°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 Monday at 21Z
api.weather.city /v1/history (nbm-qmd)
-6.5 °F normal 0.0 °F · 2 of 3
8 synoptic cycles
10th-to-90th percentile spread at that hour
api.weather.city (nbm-qmd)
10.3 °F normal 6.5 °F
current run
Milepost
1159 · laid 2026-09-20T22:26:16Z
Model
nbm-qmd · cycle 20260920T12:00Z
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
d3692a71102bb1816a1567353db833da19d24fb47a563d07aee38a7f6f96f17c
Machine
JSON