NHC Tropical Weather Outlook Explained — Yellow / Orange / Red Areas

NHC Tropical Weather Outlook Explained — Yellow / Orange / Red AreasHow to read the National Hurricane Center's Tropical Weather Outlook — yellow/orange/red colored areas showing 2-day and 7-day cyclone formation probability, the difference from the cone of uncertainty, and what triggers EMA pre-positioning.The National Hurricane Center publishes Tropical Weather Outlooks ("TWOs") four times a day during hurricane season (May 15 – Nov 30 Eastern Pacific, Jun 1 – Nov 30 Atlantic). The map shows where existing or potential tropical systems are, color-coded by NHC's confidence that they'll develop into a depression / storm in the next 48 hours and 7 days.The colored shapes

Yellow X / area: Low chance (less than 40%) of tropical cyclone formation in the next 7 days.

Orange X / area: Medium chance (40–60%).

Red X / area: High chance (greater than 60%). Pay attention.

Hurricane symbol (red spiral): Active named tropical cyclone. Intensity + track are on a separate page (the NHC track cone).

The 7-day vs 2-day outlookNHC publishes both. The 2-day is what you'd use for "should I be watching this thing today?" The 7-day is what you'd use for planning ("am I going to need to start moving boats / boarding up / advising my coastal county next week?"). The 7-day was added in 2023 — older procedures may still reference only the 5-day version.What spotters / EMA do with it

Pre-positioning: Yellow areas in the Gulf of Mexico in August trigger early warning of resource positioning. Orange areas trigger pre-positioning. Red areas trigger activation.

Early-stage tracking: Once a system has a yellow / orange / red blob over it, watch the NHC discussion text for guidance on which models are converging.

Atlantic vs Pacific basins: Both have separate outlooks. East Pacific impacts Mexico and the desert SW (via remnant moisture). West Pacific is a separate JTWC product.

This product is not the cone: Once a system is named, the cone of uncertainty (separate product) replaces the colored blob in operational decision-making.

Source: nhc.noaa.gov. Updated four times daily (2 AM, 8 AM, 2 PM, 8 PM Eastern) during hurricane season; suspended outside the season.Part of the BloomWX learn library — beginner-friendly explainers covering every surface of the BloomWX weather dashboard. Open BloomWX to see live data for any U.S. county.