How to Read
Weather Radar
Weather radar is the single most useful tool for tracking storms in real time. Once you know what you're looking at, you can see exactly what's coming and when it'll arrive.
What Radar Actually Shows
Doppler weather radar sends out pulses of energy that bounce off precipitation — rain, snow, hail, and sometimes debris. What you see on a radar map is reflectivity: how much energy bounced back. More energy = heavier precipitation = brighter colors.
The radar does NOT show clouds, fog, drizzle, or wind by itself. It shows precipitation intensity and, with Doppler capability, the motion of that precipitation toward or away from the radar site.
What the Colors Mean
Radar color scales vary by app, but the standard NWS reflectivity scale follows this pattern:
Green — Light to Moderate Rain
Light green is light rain or drizzle. Dark green is moderate, steady rain. You'll get wet but it's not dangerous.
Yellow — Heavy Rain
Heavy rain that can reduce visibility. In a sustained band, this can cause localized flooding. Pay attention.
Orange — Very Heavy Rain
Intense rainfall. Possible small hail. If you see a compact orange core, that's a strong thunderstorm cell.
Red — Extreme Rain / Hail
Extremely heavy rain, likely hail. Red cores inside thunderstorms are where the worst conditions are. Severe weather is likely.
Purple / White — Giant Hail or Tornado Debris
The most intense returns. In a supercell, this can indicate giant hail (2"+) or even a tornado debris signature (TDS). Take shelter.
How to Spot Dangerous Storms
Hook Echo
A hook-shaped appendage on the south side of a storm cell. Classic signature of a rotating supercell, often associated with tornadoes. If you see one near you, take shelter.
Bow Echo
A line of storms that bows outward. Indicates powerful straight-line winds (60–100+ mph) called a derecho. Can be as destructive as a tornado across a wider area.
Training Echoes
Multiple storm cells moving over the same area in a line, like train cars on a track. Causes extreme rainfall and flash flooding even if individual cells are moderate.
High-Reflectivity Core
A bright red/purple/white core inside a storm indicates large hail. The brighter and more compact, the bigger the hail. 2"+ hail can shatter windshields.
Tips for Reading Radar
Use the Loop
A single frame tells you where rain is. The animation loop tells you where it's going. Always watch the loop to see storm motion and speed.
Check the Timestamp
Radar images can be 5–10 minutes old by the time you see them. Fast-moving storms may be miles ahead of where the radar shows.
Zoom In
National views are good for the big picture, but you need to zoom into your county to see individual storm cells and their structure.
Live Radar on Your Phone
StormCast includes live interactive radar with storm cell tracking and NWS warning polygons overlaid so you can see exactly what's warned and what's heading your way.
