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Weather radar, explained
Start here · Radar basicsHow to read weather radar
What a radar measures, what the colors mean and how to read a loop.
Weather alertsWatch vs warning: what each one means
What a watch and a warning say for tornadoes, severe storms and floods, and how they look on a radar map.
Winter weatherHow to tell rain from snow on radar
Why the colors look alike, how the correlation coefficient shows melting, and what the beam misses near the ground.
Severe weatherWhat is a derecho? Reading a bow echo
The bowed line on reflectivity, the block of wind on velocity, and what makes a bow echo a derecho.
Severe weatherHow to spot hail on radar
Why a red core can be hail or heavy rain, what the two dual-pol maps add, and what radar can’t tell you about size.
Radar echoesWhy radar shows rain when it isn’t raining
Rain that dries up before the ground, birds and insects, clutter and a picture a few minutes old.
ForecastsWhy weather forecasts are often wrong
Why the same hour is forecast differently from one run to the next, and what a rain chance means.
Forecast mapsHow to read a GFS precipitation map
The rain, snow and sleet colors, the six-hour average rate, the pressure lines and the 540 line.
Forecast mapsHow to read a GFS temperature map
The color scale, the dashed 32°F line, and how night, day and mountains change the map.
Forecast mapsHow to read a GFS snowfall map
What the totals add up, the 10-to-1 rule and why mountain totals are rough.
Forecast mapsHow to read a 500 mb map
The height lines, troughs and ridges, and the shaded vorticity.
HurricanesHow to read a hurricane forecast map
The cone, the colored model lines, and what the strength colors and categories mean.
Doppler radarHow Doppler radar works
How the radar measures wind, why it only sees motion toward or away, and where the reading breaks down.
Severe weatherHow to spot a tornado on radar
The hook echo, the rotation pair on velocity and the debris signature.
Dual-polarizationDual-polarization radar, explained
Correlation coefficient, differential reflectivity and KDP, and how they tell rain from hail, debris, birds and insects.
3D radar3D weather radar, explained
How a 3D view is built from the radar’s tilts, what it shows that a flat map can’t, and where it can mislead.
Using AleruaHow to use the Alerua radar map
Every control on the radar page, from Product to Settings, and what the tilts see.