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Milepost
1160

TheForecast Post

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

Dallas, Texas Revisions MILEPOST 1158

Dallas's forecast for Wednesday has moved 11°F colder

92°F in the 20260919T06:00Z run, 81°F in the 20260920T12:00Z — the largest revision of any city on the roster. The current run's 10th-to-90th percentile spread at that hour is 25°F.

Successive cycles do not merely refresh a forecast; they leave a trail. For Wednesday, September 30 at 18Z in Dallas, that trail runs from 92.4°F in the 20260919T06:00Z cycle to 81.0°F in the 20260920T12:00Z — a move of -11.4°F across 8 runs.

The change sits well inside the run's own spread, which is the guidance converging rather than reversing.

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 18Z
api.weather.city /v1/history (nbm-qmd)
-11.4 °F normal 0.0 °F · 1 of 3
8 synoptic cycles
10th-to-90th percentile spread at that hour
api.weather.city (nbm-qmd)
24.6 °F normal 11.4 °F
current run
Milepost
1158 · 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
adf7e455ab80313e2f0791c3e9abdc9a428ea9b46d9b0e27dad92cd7bb5bda84
Machine
JSON