Storm Forecast helps a team prepare before a warning exists. Users inspect possible severe weather over their service area, select a forecast period, and decide what to monitor. This is a proposed capability; no forecast-ingestion or forecast-notification implementation is established by these docs.
The information journey begins with Forecast → Alert → Radar → Map → Impact → Report. These are entry points, not a mandatory sequence. A forecast may never lead to a warning, and an observed storm may enter the system without a stored forecast. Forecast ingestion does not block the first Storm Report release.
Use the forecast to prepare staffing and watch areas. Keep active warnings in Storm Alert, and measured or radar-derived evidence in Storm Radar. Forecast probabilities do not become observed hail, damaged roofs, or permission to dispatch a field team.
Start with NOAA/NWS Storm Prediction Center outlooks. The NWS briefing reference ↗ presents Day 1 and Day 2 hazard-specific outlooks, Day 3 severe-weather guidance, and Day 4–8 outlooks. The NOAA outlook GIS service ↗ is a discovery lead for geographic products, not an approved StormTrust source contract.
Preserve the native product, issue time, valid start/end, forecast day, hazard, category or probability definition, geography, and narrative. Verify the exact product version before decoding it. Do not relabel a combined severe-weather probability as hail probability, average nested contours, or turn a probability near a point into the probability that a county or roof will be damaged.
Longer-horizon guidance supports broader preparation. It does not locate a future neighborhood hail swath. Display the publisher's confidence and uncertainty statements, including cases where no risk area is drawn; absence of a polygon is not an all-clear.
Separate issued at, valid for, retrieved at, and last checked. A day label depends on the selected issuance and valid period, not the viewer's local calendar alone. Show UTC with an explicit local-time conversion.
A new issuance supersedes the live view while preserving older issuances for historical comparison. Keep the user's selected historical forecast pinned. Missing retrieval, expired guidance, and a publisher's low-risk assessment need different states. A later warning should link to the relevant forecast revision through a recorded association, never overwrite it.
A watch concerns possible severe weather across an area. A warning concerns severe weather reported or indicated by radar and calls for protective action. Keep these distinctions and the original NWS instructions visible; do not present a forecast as an imminent warning. See NWS alert definitions ↗.
Before implementation, approve the source interface, geometry and category mapping, update/freshness policy, historical retention, service-area intersection, and optional notification policy. Record retrieval and parsing evidence against a pinned product revision. The journey contract keeps forecast readiness separate from the first report release.