Observed arrival · 2026-09-23
Ninety Sky grades its own rain forecasts
A block-level rain forecast for the next 90 minutes that displays uncertainty and says it scores each prediction against observed rainfall.
- For
- People deciding whether to carry an umbrella
- Worth noticing
- It limits alerts to one of each type per half hour and suppresses them from 10 p.m. to 7 a.m.
Field notes
The described workflow combines radar motion with NOAA's HRRR and National Weather Service forecasts, which a decision model called Jev weighs against the radar. The page says each forecast is scored against what actually fell and that changes ship only when they outperform the prior version, though the extracted text does not include the linked research numbers. Coverage is stated as the contiguous United States, and the site cautions users to rely on the National Weather Service and local authorities for warnings.
Observed signals
Read the marks
Editorial observations of this landing page, not a rating.
One card from the complete issue