Fall Foliage and Climate Change

Autumn is a season well known for its colorful foliage. Driven by the combination of sunlight, temperature, and precipitation, local displays vary from year to year. However, as the climate changes, so too will this familiar natural phenomenon.

As daylight hours decrease in the fall, there is less sunlight available to power photosynthesis – the chemical process that provides nutrients to trees by converting carbon dioxide and water into glucose, which is consumed by the tree and oxygen, which is released. This, in combination with falling temperatures, tells a tree to start preparing for winter.

To do this, a tree turns off its food producers by slowly corking the connection between leaf-stems and its branches.  This blocks the movement of sugars from the leaves to the tree as well as the flow of water from the roots to the leaves.  As a result, the leaves stop producing chlorophyll, the agent of photosynthesis and the reason for the green color of summer foliage.  As the green fades, other chemicals that have been present in the leaves all along begin to show.  These include xanthophyll and carotene, which produce yellow and orange leaves, respectively. Red to purplish colors are the result of anthocyanin, a chemical produced as a result any remaining sugars trapped in a leaf.

The change of leaf color happens every year, but the timing and duration of the displays are largely dependent on temperature and rainfall. Dry, sunny days and cool nights are the ideal recipe for beautiful fall foliage. Warmer and wetter conditions, on the other hand tend to delay the color change. However, extreme conditions, such as high heat, frost, excessive rain, or drought, can be a source of stress for trees and cause the colors to change early and the leaves to fall off faster.

As our climate changes, so too will displays of fall foliage. With warmer and wetter conditions forecast for the northeast, autumn colors are expected to peak later and disappear sooner. While there will still be variability from year to year, the fall foliage season in general is expected to get shorter. Furthermore, with the increasing probability of extreme weather events, such as storms with heavy rain, leaves could be swept from trees, effectively ending the season in a single day.

These changes will have more than an aesthetic affect. They are sure to have an impact on the multi-billion-dollar a year leaf-peeping ecotourism industry in several states.

Credit: Climate Central

Weather and Art: Rainworks

Rainy days can sometimes make people feel sad or depressed. This is what inspired artist Peregrine Church to create Rainworks – artwork activated by rain. His goal, he says, is “to give people a reason to smile on a rainy day”.

Based in Seattle, a city known for precipitation, he uses a super-hydrophobic spray to create images and sayings on concrete surfaces that are only visible when wet. As concrete gets wet, it gets darker. However, the areas covered in the waterproof coating stay dry and therefore lighter in color. This contrast allows the images and sayings to be visible to passersby.

Essentially street art, his first piece in 2014 was written on a city sidewalk and said “Stay Dry Out There”. He was soon joined his friend by Xack Fischer in creating Rainworks across the Emerald City.

In 2016, they started selling their specially formulated spray online. They also offer tutorials on their website to help people create their own Rainworks around the world. The spray according to the artists, is eco-friendly and biodegrades over the course of 2 to 4 months.

To date, more than 200 Rainworks have been created across five continents. You can find their locations (and add your own) on the Rainworks map.

A Rainwork in Yokohama, Japan. Image Credit: Rainworks Gallery

NYC Monthly Weather Summary: October 2018

October had a split personality in New York City this year. It started off unseasonably warm, but then temperatures plunged dramatically in the middle of the month and remained mostly below average until Halloween. Highs ranged from a balmy 80°F to a brisk 50°F. But in the end, these extremes balanced each other out. The city’s mean temperature for the month was 57.7°F, which is only 0.8°F above average.

In terms of precipitation, the city was fairly dry. Overall, 3.59 inches of rain was measured in Central Park. Of this total, 35% fell in single day during the first nor’easter of the season. On average, the Big Apple gets 4.40 inches of rain for month. This October also marked first month since June that the city received below average rainfall.

Credit: The Weather Gamut

Weather Lingo: Indian Summer

Autumn is a season known for colorful leaves and falling temperatures. Every once in a while, however, summer warmth makes a resurgence. When this happens, it is often dubbed “Indian Summer”.

This weather phenomenon, according to the NWS glossary, is defined as “an unseasonably warm period near the middle of autumn, usually following a substantial period of cool weather.”  In the northeastern US, it is generally associated with an area of high pressure to the south that ushers warm air northward.

In popular use since the 18th century, the exact origins of the term are a bit foggy. One of the more reasonable explanations behind this unique phrase suggests a connection to when Native Americans began their hunting season, but no one knows for sure.

In other parts of the world, this summer-like weather goes by a variety of different names. In Europe, a number of countries associate the unusual warmth with the nearest saint’s day. It is known as “St. Luke’s Little Summer” if it develops in October or a “St. Martin’s Summer” if it occurs in November. In temperate parts of South America, it is simply known as “Veranico” (little summer).

The timing and intensity of these autumn warm spells vary from year to year. Nevertheless, when they do occur, they usually only last a few days. So, as we inevitably move toward winter, enjoy them while you can.

Fall foliage. Credit: Melissa Fleming

Flashback Facts: Sixth Anniversary of Hurricane Sandy

Today marks the sixth anniversary of Superstorm Sandy. Here is a look back at some of the facts from that historic storm.

  • Sandy was the largest hurricane to form in the Atlantic basin. Its tropical storm force winds spanned 900 miles in diameter.
  • Impacts from Sandy were felt across 24 states, from Florida to Maine and as far inland as Michigan.
  • The most severe damage occurred in New York and New Jersey.
  • The storm surge at The Battery in NYC reached a new record high of 13.88 feet, flooding the streets, tunnels, and subways of lower Manhattan.
  • Sandy was responsible for 72 deaths in the US. Of those, 44 were in NYC and 24 were in the city’s hard hit borough of Staten Island.
  • More than 8 million people across 21 states lost power because of the storm.
  • Sandy caused more than $70 billion in damage.
  • It was the fourth costliest storm in US history after Katrina, Harvey, and Maria.

Superstorm Sandy. Credit: NOAA

First Nor’easter of the Season Slams NYC

The first nor’easter of the season slammed the northeastern United States on Saturday. Heavy precipitation, strong winds, and coastal flooding were reported across the region.

Here in New York City, the storm dumped 1.34 inches of rain in Central Park. Its powerful winds knocked down trees and caused power outages around the city’s five boroughs. The storm also caused significant travel delays, including shutting down part of the FDR Drive because of flooding.

While nor’easters are not uncommon at this time of year, this one was interesting because it started off as a hurricane in the eastern Pacific. Hurricane Willa made landfall near Mazatlan, Mexico on Tuesday night and then moved inland toward Texas. From there, the storm’s remnants merged with a cold front and became re-energized. Traveling in the jet stream, it worked its way up the eastern seaboard and became a nor’easter.

First nor’easter of the season downed trees and branches in Queens. Credit: D. Herrick

September 2018: Earth’s Fourth Warmest September on Record

Our global temperature continued its upward trend last month with September 2018 tying 2017 as the fourth warmest September ever recorded on this planet.

According to the State of the Climate report by NOAA’s National Centers for Environmental Information, Earth’s combined average temperature for the month – over both land and sea surfaces – was 60.4°F, which is 1.40°F above the 20th-century average. September also marked the 405th consecutive month with a global temperature above its long-term norm. That means the last time any month posted a below average reading was December 1984.

While heat dominated most of the planet this September, some places were particularly warm, including much of Europe, Russia, the Middle East, and both the eastern and southwestern regions of the United States. For the contiguous US as a whole, September 2018 marked the fourth warmest September on record.

These soaring temperatures are largely attributed to the long-term trend of human-caused climate change. ENSO-neutral conditions prevailed in September, which means there was neither a warm El Niño nor a cool La Niña in the Pacific to influence global weather patterns.

Year to date, the first nine months of 2018 were the fourth warmest such period of any year on record. Global temperature records date back to 1880.

September 2018 was the planet’s 4th warmest September on record. Credit: NOAA

Fall Finally Arrives in NYC

After an unusually warm September and a rather balmy start to October, it finally felt like autumn in New York City this weekend.

According to the NWS, the temperature in Central Park only made it to 55°F on Saturday and 58°F on Sunday. The overnight lows were also rather chilly in the mid-40s. This was the coldest weather the city has seen since last spring. Its rather sudden arrival was a bit a jolt for many New Yorkers who had to scramble to find their jackets and sweaters that had been tucked away for months.

The average high and low for NYC at this time of year is 65°F and 51°F, respectively.

Credit: The Weather Gamut

Hurricane Michael Devastates Florida Panhandle

Hurricane Michael, the 13th named storm of this Atlantic Hurricane season, made landfall near Mexico Beach, Florida on Wednesday. It was the strongest storm on record to hit the Florida Panhandle.

Coming ashore with sustained winds measured up to 155mph, Michael was classified as a high-end category-four hurricane. Its powerful winds sheared roofs off buildings, uprooted trees, and toppled power lines. Storm surge flooding was also a major force of destruction. The NHC estimates the water reached between nine and fourteen feet above normally dry ground from Mexico Beach eastward through Apalachee Bay.

Fueled by the unseasonably warm waters of the Gulf of Mexico, Michael intensified rapidly as it moved closer to shore. According the NWS, Michael was the strongest hurricane to make landfall in the US since Hurricane Andrew in 1992. It was also the strongest storm to ever hit this country in the month of October.

Moving quickly, the storm traveled across the Florida Panhandle toward the northeast. Its strong winds and heavy rain caused flashing flowing and power outages in several states.

As of Friday, the death toll from this historic storm stands at sixteen. But sadly, officials say that number is expected to rise as search and rescue efforts continue in the hardest hit areas.

Hurricane Michael makes landfall near Mexico Beach, FL. Credit: NOAA

Summerlike Heat in October for NYC

The calendar says October, but it still feels like summer in New York City.

The temperature in Central Park soared to an unusually balmy 80°F on Wednesday. While this did not break any records, the overnight low did.  The mercury only dropped to 71°F, setting a new record warm minimum temperature for the date. The previous record of 69°F had been in place since 1949.

It is also interesting to note that Wednesday’s low was warmer than the date’s normal high. The city’s average high and low temperatures for this time of year are 66°F and 52°F, respectively.

New record warm low temperature set in NYC. Credit: The Weather Gamut