Norman Kuring/NASA Physical oceanographers will sometimes point out that the ocean has weather and seasons, much like the atmosphere. Masses of water with different temperatures, salinities, and nutrient levels clash and mix like warm and cold fronts in the air. Different plant-like species—phytoplankton—bloom, spread, and die back with the different conditions. Ocean currents swirl in turbulent fronts and eddies—much like tornadoes and hurricanes, though far more productive than destructive. Springtime in the North Atlantic Ocean is a time of great change, turbulence, and productivity. Increasing sunlight, nutrient runoff from land and upwelling from the deep, and changeable atmospheric weather all conspire to color the ocean surface with interesting patterns. The composite image above shows the northwest Atlantic Ocean on May 14, 2015, with the New England and Canadian Maritimes in the background. The image was constructed from data acquired by the Visible Infrared Imaging Radiometer Suite (VIIRS) sensor on the Suomi NPP satellite. On the left side of the image, several circular patterns are traced out by the light green phytoplankton near the surface. These rings are likely eddies that have spun off of the Gulf Stream, which turns east toward Europe in this region. The underwater plateau known as Georges Bank is also made visible (indirectly) by the plankton. The Labrador Current and the Gulf Stream meet in this area, and the relatively shallow water promotes an abundant crop of phytoplankton, marine plants, shellfish, finfish, and marine mammals, all the way up the food chain. The bank is marked by bright swirls of color in the image. Patches and swirls of phytoplankton continue to the north and east from the bank, indicating regions where there are significant nutrients near the surface and other water conditions that promote blooms. Though it is very difficult to identify the genus and species of phytoplankton from a satellite, researchers working from ships in the North Atlantic confirmed that at least some of the phytoplankton blooming in May were diatoms, including Guinardia delicatula. The Gulf of Maine and Georges Bank have historically been some of the most productive fishing grounds on the planet. Overfishing and pollution brought significant declines in the late 20th century, though regulation and changes in fishing practices may now restore some of the abundance in the local waters. Researchers from the Woods Hole Oceanographic Institution, North Carolina State University, and NOAA have been regularly monitoring the region with ship-based studies, ocean models, and automated, moored instruments in order to keep track of phytoplankton and algae species, particularly those that lead to toxic algae blooms.

Many think of spring as a blissful time of the year when flowers bloom, but for some parts of the United States, it spawns the year’s most dangerous weather.

For instance, spring is when there is the highest potential for damaging tornadoes, among other threats.

Here are four different ways weather can wreak havoc during the spring.

Spring thunderstorms can produce strong tornadoes

Severe thunderstorms are hazardous during the spring in the U.S. because there is potential for damaging winds, tornadoes and flooding rainfall.

AccuWeather meteorologists agree tornadoes are by far the most extreme event in the spring. They are also the most prominent during this time. The United States has a unique setup that creates favorable conditions for tornado development.

“The risk is greatest in the spring due to the potential for large contrasts of dry, moist and cold air,” AccuWeather Senior Meteorologist Dan Kottlowski said. 

Those come together to produce some of the most violent weather conditions on Earth.

“If these ingredients come together quickly, there can be multiple tornadoes and a higher potential for EF4 and EF5 tornadoes, the most deadly and destructive tornadoes,” Kottlowski said.

“Several tornadoes in one area can lead to tremendous damage and lives taken,” AccuWeather Lead Long-Range Meteorologist Paul Pastelok said. “Isolated tornadoes runs with just a few miles of coverage. Outbreaks can be over 200 miles of risk area,” he said.

Snowstorms can cause disruptions to travel

In the early spring, snowstorms are still a potential extreme weather problem.

“In the past some of the biggest snowstorms for cities like Denver, Cheyenne, Wyoming, and even Chicago have occurred during the early spring,” Kottlowski said.

As March and April are transition months, extreme warmth can often be followed by extreme cold. The contrasts between warm and cold help fuel powerful spring storms.

Springflooding can be a significant threat to lives, property

Flooding is not an event to be forgotten in the spring. During spring’s warmup, rainfall and melting snow can very easily cause large amounts of runoff in a short period of time.

While severe thunderstorms and tornadoes are the biggest threat in spring, significant flood events can occur due to rapid snow melt, ice jams or just from heavy rain events, according to Pastelok.

According to the United States Geological Survey (USGS), flooding causes about $2 billion in damage each year and kills an average of 165 people.

The Federal Emergency Management Agency (FEMA) outlines spring flooding in particular due to its high risks.

FEMA explained how spring brings heavy rains which can lead to severe flooding by oversaturating the ground, overfilling storm drains or causing rivers to spill over their banks or levees.

Gusty winds can trigger dust storms 

One other extreme weather event is dust storms and firestorms. The strongest winds occur during March and April due to the development of big and powerful surface storms developing in the lee of the Rockies then moving east.

“If an area is very dry or drought stricken and experiences these strong winds, dust storms can develop,” Kottlowski said.

Dust storms can turn into firestorms if accidental or careless burning takes place.

Firestorms in the Plains can consume hundreds of square miles of grassland and forests.

“If houses and buildings are in the path of these fast-moving firestorms, total destruction can take place, but unlike tornadoes, firestorms can be prevented,” Kottlowski said.