what does purple mean on the weather map

What does purple mean on the weather map? You know you need to be able to read weather maps to understand meteorological events.

That is when you have to learn about what different colors indicate on a map.

And interestingly, the color purple always piques curiosity, which is why it makes sense to unravel its significance.

Essentially, colors on weather maps represent different things about potential impacts, atmospheric conditions, etc., but what does the color purple mean on a weather map?

The color purple on weather maps indicates extreme conditions, including freezing rain, heavy snow, etc., usually depending on the map’s specific context.

What Does Purple Mean on the Weather Map?

meaning of purple on weather map

Modern weather maps convey a wealth of information about the short-term conditions of the atmosphere.

They have been in use since 1875 which were utilized to summarize yesterday’s weather.

Meteorologists now employ radar scanning and the color spectrum to graphically represent the weather with extremes in incremental shades of purple.

Areas expected to experience nominal rain or light showers are assigned the color blue.

The heavier the rainfall, the darker the shade used.

Where heavy precipitation is expected such as in a thunderstorm, red to purple is used, with the deepest purple where the rainfall is likely to be heaviest. 

Color Used to Indicate Hailstorms

color used to indicate hailstorms

Even hail can be detected by radar and returns a signal much like rain.

However, modern radar technology has become so efficient it can determine the size of the hail pellets forming inside thunderstorms.

On images hail data is assigned the pinks, appearing as spots within the reds and purples of thunderstorms.

An Important Consideration

The false color reds and purples of assigned storm data make them easy to spot on a map.

Meteorologists collect data by slicing through the storm to study the updrafts.

But, on the resulting image, the instantly recognizable colors are particularly useful when issuing extreme weather warnings to the public.

Fact: On weather maps, intense weather events with heavy rain are represented by deep reds and warmer colors.

Interpretation of Purple on Weather Maps 

interpretation of purple on weather maps

Due to climate change, the color purple appears on weather maps more often.

In 2013 the Australian Bureau of Meteorology added deep purple and pinks to their interactive weather maps.

The recalibration was necessary to be able to represent the extremely high temperatures of 500 plus they were experiencing more regularly.

Radio waves detect objects, including water droplets and ice, regardless of the weather and were developed for use in meteorology post war. 

Using the Doppler Effect, radars collect data translated by computer into colored images.

On radar, heavier rain is shown in warmer colors including deep reds and purples.

Satellite Imagery and Purple on the Map

satellite imagery and purple on the map

Satellite imagery can be in the visible, infrared or water vapor. Visible satellite images use true color and so only work in daylight.

Infrared images report temperatures and water vapor images humidity.

Computers add false colors to these images, including purple to show greater intensity so meteorologists can monitor temperatures and air density.    

Precipitation maps use rain data to create images scientists can use to decide how rain is likely to fall, such as liquid drops, ice or snow.

This helps make predictions about when and where the rain will fall according to its intensity in false color.

Fact: Oranges and reds indicate moderate to heavy rain and hail, and purple indicates strong to severe thunderstorms.

The Significance of Purple in Meteorology

the significance of purple in meteorology

Climate change research predicts the Earth’s population will experience more frequent, stronger, and longer-lasting storms.

Keeping that in mind, countries are looking for other ways to indicate severe weather.

Australia is a good example. But, Australia is not the only country recalibrating the colors on its weather maps.

Many countries will face the challenges of extreme weather with higher ranges in their data and purple on maps becoming more normal. 

The Role of Winter Storms

the role of winter storms

Winter storms are already showing an upturn in frequency and severity.

As sea temperatures rise to create a wider difference between sea temperatures and land temperatures, storms have more water vapor to use as fuel and greater ferocity as weather fronts collide.

With the air holding more water, there is more available to fall as rain.

Because it is the difference between land and sea temperatures that trigger supercell storms, coastal areas are especially vulnerable.  

The Role of Extreme Weather

The extreme weather upturn is causing havoc all over the world.

As well as more purple on maps for severe thunderstorms, climate change will trigger other extreme weather events.

the role of extreme weather

These include:

  • Heatwaves
  • Cold snaps
  • Cyclones
  • Hurricanes
  • Droughts
  • Torrential rain
  • Flooding
  • Wildfires

In 2021, Zhengzhou, China experienced a years’ worth of rain in one day.

Fact: The US and Canadian cities saw record breaking day and night-time temperatures, and Siberia was in a drought lasting 150 years, suggesting the impact of extreme climatic shifts.

The Effect of Global Warming

the effect of global warming

Because of global warming, research and modeling suggest the precipitation intensity will increase worldwide by 16 – 24%.

It is going to rain harder.

South Asia and Central Africa are predicted to be worse affected.

As much as more rain is expected so are more droughts, with areas experiencing soil drying out faster, lower levels of runoff and lower stream flow. 

All the modeling suggests the Mediterranean and southern Africa will see a decrease in rain.

Does Purple on Radar Mean Tornado?

Tornadoes spawn in intense superstorms that are colored purple on the weather maps.

It is a column of air that rapidly rotates as it reaches from a thundercloud down to the ground.

They are violent winds causing extremes of damage. Wind Speeds of 300 miles per hour have been recorded.

does purple on radar mean a tornado

On most radar images tornados are assigned two false colors:

  • Green for winds moving toward the radar
  • Red for those moving away

The slower the wind, the darker the shade.

As a result, images and maps reveal tornados as a dot of red surrounded by green.

As storms have increased in frequency and severity, so have the tornadoes that accompany them and consequently, the red dot is more likely to become a deep purple.

Fact: Although it is difficult to predict where a tornado will touch down, scientists issue warnings once radar picks up the red of early tornado formation.

Tornado Indicators on Radar 

tornado indicators on radar

When a tornado has been indicated by radar as in rotation, an official tornado warning is given.

Further warnings will confirm that a tornado has formed.

Scientists understand the tornado formation process and can recognize the early indicators announcing that a tornado is about to spawn. 

A characteristic of a tornado producing storm is the formation of a hook-like appendage.

On radar, it is a well-established indicator of tornados in a supercell.

The hook echo is due to changing vertical winds that are heavy with rain, hail and debris wrapping around the updraft as rotating tornados at the hook’s center.

On the radar, they show up as deep red areas lower down in the storm on the southwestern side.

More about a Radar Pattern to Identify Tornadoes

details on radar pattern for detecting tornadoes

During the research, scientists noticed a radar pattern with intense rotation appearing just a few miles above the ground surface whenever a tornado was about to touch down.


Although this distinctive tornado vortex signature, TVS, does not always mean a tornado, it strongly increases the possibility. 

In fact, coupled with the presence of a hook echo, identifying a TVS provides scientists with a reliable way to increase the accuracy and effectiveness of tornado warnings.

tornado vortex signature

A TDS is a tornadic debris signature; sometimes it is referred to as the debris ball.

On radar is a highly reflective collection of debris lifted aloft by a tornado.

It is a mix of anthropogenic material resulting from human activity and biomass, plant-based debris.

A TNS debris ball is normally the result of an EF3 or above tornado, with the flying debris rather than wind and rain being the most immediate threat to life. 


What does purple mean on the weather map?

The color purple on weather maps represents extreme conditions such as heavy snow and freezing rain.

Meteorologists rely heavily on the color spectrum when reporting weather conditions and issuing safety advisories to the public.

Understanding the meaning of purple on weather maps is essential for preparation and safety as the frequency of extreme weather events increases.