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Milepost
1185

TheForecast Post

A chronicle of American weather and climate  ·  Wednesday, 23 September 2026

Salt Lake City, Utah Revisions MILEPOST 1183

Salt Lake City's forecast for Wednesday has moved 9°F colder

76°F in the 20260921T00:00Z run, 67°F in the 20260922T18:00Z — the largest revision of any city on the roster. The current run's 10th-to-90th percentile spread at that hour is 14°F.

Successive cycles do not merely refresh a forecast; they leave a trail. For Wednesday, September 30 at 00Z in Salt Lake City, that trail runs from 76.2°F in the 20260921T00:00Z cycle to 67.0°F in the 20260922T18:00Z — a move of -9.3°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 Wednesday at 00Z
api.weather.city /v1/history (nbm-qmd)
-9.3 °F normal 0.0 °F · 1 of 6
8 synoptic cycles
10th-to-90th percentile spread at that hour
api.weather.city (nbm-qmd)
14.5 °F normal 9.3 °F
current run
Milepost
1183 · laid 2026-09-23T04:25:16Z
Model
nbm-qmd · cycle 20260922T18:00Z
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
e256898632d8deeaa8c7aa322ce9ffebc50039c55f4eeed1a2781003d0902cf9
Machine
JSON