Why Heavy Rain Events are Becoming More Common

Torrential rain events and the flooding they cause are nothing new. Global warming, however, is helping to make them more likely.

Heavy rainfall trends in NYC. Credit: Climate Central

According to the most recent National Climate Assessment, heavy precipitation events have increased in both frequency and intensity across the United States. While there are seasonal variations with different regions, the greatest increases have been observed in the northeast.

Climate scientists attribute this increase in heavy precipitation to our warming world. As greenhouse gases warm the atmosphere, the air is able to hold more water vapor. More specifically, according to the Clausius–Clapeyron relation, for every increase of 1°F, the saturation level of the atmosphere increases by about 4%. That means there is more evaporation from oceans, rivers, and lakes, and therefore more water vapor available to condense and fall as precipitation.

Heavy rain events have a number of consequences, including an increased risk of both flash floods and river floods. This, in turn, is a threat to life and property. Over the long-term, it also affects insurance rates and property values. According to NOAA, individual billion-dollar flooding events (excluding tropical cyclones) in the U.S. have added up to $39 billion in losses since 2010.

As our global temperature continues to rise, experts say we should expect to see more extreme rain events, even in areas where overall precipitation is projected to decrease. In other words, when it rains, it will likely pour.

Downpours have been getting more frequent and intense across the US. Credit: Climate Central and NCA4

Heavy Rain Drenches NYC and Its Subways

An intense rainstorm swept through New York City on Monday. With bands of torrential downpours, it unleashed more than half a month’s worth of rain in just a few hours.

According to the NWS, 2.82 inches of rain was measured in Central Park. While that is an impressive total, it did not break the daily rainfall record for the date. That honor belongs to April 16, 1983 when 3.29 inches of rain was reported. New York City, on average, gets 4.50 inches of rain for the entire month of April.

The heavy rain caused flash flooding and disrupted travel across the city. Torrents of water poured into several subway stations through leaks in the ceiling and down the entrance/exit steps. During the morning commute, the MTA announced that several stops, including the 145th St station on the Number 1 line and the 42nd St-Bryant Park stop on the F and M lines, would be bypassed because of “excess water”.  Significant delays and cancellations were also reported at the area’s airports.

This type of heavy rain event, according to NOAA, is expected to become more common in the northeast as global temperatures rise and precipitation patterns change.

Heavy rain sends water cascading down the steps of the 145th St Station of the No. 1 train in NYC. Credit: Josh Guild/Twitter.

Summer Preview Brings NYC First 80° of the Year

It felt more like June than April in New York City on Friday. The temperature in Central Park soared to 82°F, marking the city’s first 80-degree day of the year.

Topping out at 22°F above average, the day was more than unseasonably warm. However, it was not a record breaker. That honor belongs to April 13, 1977, when the mercury soared to 88°F. The low temperature was 60°F, which ironically is the normal high for the date.

After an extended winter that included four nor’easters in March and a snowy start to April, many New Yorkers took full advantage of this summer preview. The parks and outdoor cafes were packed.

This spring heat was the result of a ridge in the jet-stream that allowed warm southern air to move further north than it normally would at this time of year.  While the balmy conditions are forecast to remain in place through Saturday, temperatures are expected to plummet into the 40s on Sunday. So, enjoy it while it lasts, but get ready for weather whiplash!

A summer preview for NYC. Credit: The Weather Gamut

Hurricane Names Harvey, Irma, Maria and Nate Retired

There will never be another hurricane by the name of Harvey, Irma, Maria, or Nate. The World Meteorological Organization (WMO) has announced that it is officially retiring these names from its list of Atlantic cyclones.

The WMO is responsible for naming tropical storms and hurricanes around the world.  It maintains a set of six rotating lists for each hurricane-prone region. After a six-year cycle, names are re-used.  Names are only retired when a storm was particularly noteworthy – causing a large number of fatalities or an extraordinary amount of damage.

The 2017 Atlantic hurricane season was brutal, but four storms were particularly destructive. Hurricane Harvey, a category-4 storm, made landfall in Texas and dumped a record-breaking amount of rain in the Houston area, unleashing catastrophic flooding. Irma clobbered the Florida Keys as category-4 hurricane, but its impacts were felt throughout the entire Sunshine state. Hurricane Maria made landfall in Puerto Rico as a high end category-4 storm and knocked out power to more than 90% of the island for months. Nate hit the US Gulf Coast as a category-1 storm, but most of its deadly impacts were felt in Central America when it was still a tropical storm.

According to the National Hurricane Center, 86 storm names have been retired since the current naming system began in 1953. This year marks the fifth time that four or more names have been retired from a single season. Three of those -1955, 1995, and 2004 – each had four names retired. In 2005, five names were retired – the most ever from one hurricane season.

Starting in 2023, when last year’s list is recycled, the names Harvey, Irma, Maria, and Nate will be replaced by Harold, Idalia, Margot, and Nigel. Some other notable retired Atlantic Basin storm names include: Andrew, Katrina, Irene, and Sandy.

The 2018 Atlantic hurricane season officially begins on June 1.

Four names from the 2017 Atlantic hurricane season are retired. Credit: WMO

Do April Showers Really Bring May Flowers?

The phrase, “April showers bring May flowers “ has been around for centuries. It is derived from a poem written in the 1500s by Thomas Tusser – an English poet and farmer. This old adage, however, does not hold true in the northeastern United States.

Coming on the heels of the snowy months of winter, April typically produces more rain than snow. Many people, therefore, consider it a rainy month. Since water is necessary for the overall survival of plants, they also associate it with the bloom of flowers in May. Nevertheless, according to botanists, perennials – the plants that go dormant in winter and re-grow in the spring – are more dependent on the soil moisture derived from winter snowmelt and the long-term local precipitation pattern.

In the end, though, temperature is the most significant factor in determining when a flower will bloom. As soon as the weather becomes more spring-like, flowers will start to blossom, regardless of how much it rained in April or whatever the prior month was. That said, a “false spring” – a warm spell that triggers flowering but is followed by a hard frost – can kill the fragile blooms.

It is also worth noting that April is not typically the wettest month of the year for most places in the US. In New York City, July, on average, takes that honor because of the downpours associated with its strong summer thunderstorms.

Peonies in bloom. Credit: Melissa Fleming

Speaking Event: The Art and Science of Climate Change

Climate change is a complex scientific subject with a plethora of data-rich reports that detail its causation and diverse impacts. However, as important as all that information is, not everyone responds to facts and figures or charts and graphs. That is why art, which taps into human emotion and tells visual stories, can help create new pathways to understanding this critical issue that affects us all.

On Saturday, April 7, I will be giving a presentation titled, The Art and Science of Climate Change, at the Ann Street Gallery in Newburgh, NY. Blending my two passions, it introduces the basic science of climate change and explores how artists from around the globe are reacting to its various impacts and possible solutions.

Currently on view in the gallery is Anthropocene, a group exhibition in which I am showing pieces from my Under Glass series. Curated by Virginia Walsh, the show has been well covered in the press, including a blog post on Climate You and a nine page feature in Issues in Science and Technology, a magazine published by The National Academies of Sciences, Engineering, and Medicine.

If you are in the area, please stop in and say hello. The program begins at 2PM and it is also the final day of the exhibition. The Ann Street Gallery is located at 104 Ann Street, Newburgh, NY.

“Memory: 41 years” is on view in the Anthropocene exhibit. Credit: Melissa Fleming

Spring Storm Sets New Daily Snowfall Record in NYC

A spring snowstorm slammed the northeastern United States on Monday. Coming on the heels of a mild Easter weekend, it felt like weather whiplash across the region.

Here in New York City, the storm dumped 5.5 inches of snow in Central Park, setting a new daily snowfall record for the date. The previous record of 2 inches had been in place since 1871. The storm also marked the snowiest April day the city has seen in 36 years.

Despite the ground being relatively warm, the heavy, wet snow was able to accumulate because it came down very quickly. La Guardia Airport reported a snowfall rate of 2 inches per hour.

The city, on average, gets 0.6 inches of snow for the entire month of April.

Source: NWS

March 2018 was More of a Lion Than a Lamb in NYC

There is an old saying that March comes in like a lion and goes out like a lamb. It refers to the transition from winter to spring that takes place during the month and the change in weather that usually follows. In New York City this year, however, that tradition went out the window as March turned out to be colder than February.

This type of temperature flip-flop, according to the NWS, has only occurred three other times in New York City history – 1890, 1891, and 2017.

This March, twenty-six out of thirty-one days posted below average temperatures. Four of those days had highs that did not get out of the 30s. In the end, the city’s mean temperature for the month was 40.2°F, which is 2.3°F below normal.

The month was also unusually wet. The four nor’easters that blasted the region in as many weeks brought the city copious amounts of precipitation. In all, we received 5.17 inches of rain, which is 0.81 inches above average. Snowfall was also abundant, with 11.6 inches measured in Central Park. Of that total, 8.4 inches fell during the fourth and final nor’easter of the month. March, on average, usually only brings the city 3.9 inches of snow.

New York City weather records date back to 1869.

March was colder than February in NYC. Credit: The Weather Gamut

National Drought Update: Early Spring 2018

The northeastern United States received copious amounts of precipitation from the four nor’easters that blasted the region this month. Much of the rest of the country, however, has been parched.

According to the latest report from the U.S. Drought Monitor, 31% of the nation is dealing with some form of drought. While this number represents a slight improvement for California, the situation in the southern plains and the southwest has been getting worse. Parts of the Texas Panhandle, western Oklahoma and southwestern Kansas are in exceptional drought, the worst possible category.

Drought conditions have also been building in parts of the southeast. In Florida, according to the state’s Forest Service, dry conditions have fueled more than 1000 wildfires across the peninsula since the beginning of the year.

The US Drought Monitor is a weekly publication produced by a partnership of government agencies, including the National Drought Mitigation Center, the United States Department of Agriculture, and the National Oceanic and Atmospheric Administration.

Credit: US Drought Monitor

Fourth Nor’easter of the Month Slams NYC

The calendar says spring, but it felt more like winter in New York City on Wednesday as the fourth nor’easter of the month slammed the region.

According to the NWS, the storm dumped 8.4 inches of heavy, wet snow in Central Park, setting a new daily snowfall record for the date. The previous record of 7.1 inches had been in place since 1958. The city, on average, gets 3.9 inches of snow for the entire month of March.

This storm was the fourth nor’easter to affect the city and region in less than three weeks. The others were on March 2, March 7, and March 13. This one, however, was by far the snowiest. It was also the first time since 1992 that the city saw at least 6 inches of snow from a spring storm.

The reason for the plethora of nor’easters this month involves something called the North Atlantic Oscillation (NAO). Stuck in its negative phase for weeks, it has caused the jet stream to dip south over the eastern US and steer storms toward the northeastern seaboard.

View of the fourth nor’easter to hit the east coast this March. Credit:  RAMMB/CIRA/CSU