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.
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
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
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.
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
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
Written by 91 scientists from 40 countries, the report finds that quick and dramatic action needs to be taken to avoid a warming increase of 1.5°C (2.7°F) above pre-industrial levels. Without aggressive cuts to global greenhouse gas emissions, the planet is expected to reach this warming threshold between 2030 and 2052.
The Paris Agreement set the target of holding global warming to 2°C (3.6°F) above pre-industrial levels and urged countries to pursue an even tighter cap of 1.5°C (2.7°F) if possible. This more aggressive goal was added at the urging of officials from low-lying island nations – those most susceptible to sea level rise. As such, the IPCC began to look more closely at what 1.5°C (2.7°F) of warming would mean for people and ecosystems around the planet.
Previously, scientists thought that the most severe effects of climate change could be held off if the planet stayed below 2°C (3.6°F) of warming. However, this report shows that those impacts will come sooner, at the 1.5°C (2.7°F) mark. These consequences include coastal inundation from rising seas, worsening droughts and wildfires, as well as food shortages and mass die-offs of coral reefs. An extra half-degree Celsius, from 1.5°C to 2°C, would magnify those impacts.
To avoid the worst case of these types of effects, the report says the global economy needs to be transformed within the next few years. More specifically, greenhouse gas pollution must be reduced by 45% from 2010 levels by 2030, and 100% by 2050. While this is technically possible, the report also highlights it will require enormous political will.
Under the Paris Agreement, every country around the globe submitted individualized plans to reduce its greenhouse gas emissions known as nationally determined contributions (NDCs). While an important first step, these are not enough to meet the agreement’s 2°C (3.6°F) goal, to say nothing of the more aspirational target of 1.5°C (2.7°F). In fact, they would allow for 3°C (5.4°F) of warming by the end of the century. However, the agreement does legally obligate countries to reconvene every five years to present updated plans spelling out how they will deepen their emissions cuts.
For the US, the second largest carbon polluter in the world after China, political will for climate action is something that is sorely lacking. President Trump announced plans to withdraw the US from the Paris Climate Agreement and has been rolling back his predecessor’s Clean Power Plan, the principle aspect of this country’s NDC.
Nonetheless, 2018 marks the halfway point between the passage of the Paris Climate Agreement in 2015 and the 2020 target for countries to begin ratcheting up their greenhouse gas cutting commitments. As such, this new report will be key to the discussions at the upcoming UN Climate Conference in Katowice, Poland this December.
September 2018 was another temperature roller coaster in New York City. Highs ranged from an unseasonably cool 62°F to a sizzling 93°F. However, with fifteen days posting above average temperatures, including three with readings in the 90s, the heat won out in the end. This warm finish was also aided by the unusually balmy overnight lows that were seen throughout most of the month. In fact, on September 5, the low only dropped to 77°F. That tied the record high minimum temperature for the date, which was set in 1985. In the end, the city’s mean temperature for the month was 70.7F°, which is 2.7°F above average.
In terms of precipitation, September was a soggy month in the Big Apple. In all, 6.19 inches of rain was measured in Central Park. Of this impressive total, 51% fell on just two days, each of which saw flash flooding around the five-boros. The city, on average, gets 4.28 inches of rain for the entire month.