Fall Nor’easter Transitions to Sub-Tropical Storm Melissa

The nor’easter that has been battering the northeast coast of the US for several days transitioned to Sub-Tropical Storm Melissa on Friday. It is now the 13th named storm of the Atlantic hurricane season.

Lingering offshore since Wednesday, states from the mid-Atlantic to New England have been feeling its impacts in the form of strong winds, heavy rain, and coastal flooding. On Friday, its sustained winds were measured up to 60 mph.

Classified as subtropical, Melissa is a hybrid between a tropical storm and a regular low-pressure system. A tropical system is fueled by the latent heat released by the evaporation of ocean water while a regular storm is powered by the temperature contrast between air masses. Hybrids are able to access both energy sources.

The National Hurricane Center expects Melissa to become post-tropical and move further out to sea over the weekend.

Subtropical Storm Melissa swirling off the coast of New England. Credit: NOAA

What Causes the Smell of Rain?

Rain is often associated with particular smells. But, rain itself is odorless. So, where do these aromas come from?

The distinctive scent that lingers in the air after a rainstorm is known as petrichor. It is the product of two reactions that occur when rainwater hits the ground. Its main driver is a soil-dwelling bacteria called actinomycetes. These microorganisms thrive in moist conditions, but as the soil dries out, they produce spores. These are then released into the air by the moisture and force with which the rain hits the ground. This happens at the same time the rainwater is mixing with oils that were secreted by plants onto nearby rocks and soil during times of dryness. Together these reactions produce the musky petrichor smell, which is particularly strong after a long dry spell. The term was coined in 1964 by two Australian scientists, Isabel Joy Bear and RG Thomson. They derived it from the Greek words, “petra” meaning stone and “ichor”, the term used to describe the blood of the gods in ancient mythology.

A different, and often more pungent, rain smell is associated with thunderstorms. After the powerful electric charge of a lightning bolt splits the oxygen and nitrogen molecules in the atmosphere, they often recombine as nitric oxide. This, in turn, interacts with other atmospheric chemicals to form ozone (O3). When people say they can “smell the rain coming”, this is the scent they detect as it often arrives in the wind ahead of an approaching storm.

Credit: freepik

October Begins with Weather Whiplash in NYC

Autumn is a transitional season where a few warm days still pop up as cooler temperatures gradually take hold. This week in New York City, however, it felt like we jumped from mid-July to late October in only one day.

On Wednesday, the temperature soared to a sweltering 93°F, setting a new record high for the date. The previous record of 90°F had been in place since 1927. Then, the temperature plummeted overnight. On Thursday, the mercury only made to 63°F.  While not a record-breaker, it was the coolest day the city has seen in months.

The normal high for this time of year in the Big Apple is around 70°F.

Credit: The Weather Gamut

Record Breaking October Heat in NYC

The season officially changed to autumn last week, but it felt more like summer in New York City on Wednesday.

The temperature in Central Park soared to 93°F, setting a new record high for the date. The previous record of 90°F had been in place since 1927. Wednesday also marked the second warmest October day ever recorded in the Big Apple. Only October 5, 1941, was warmer when the temperature hit an unseasonably sultry 94°F.

This type of heat is unusual for NYC in October. In fact, this was only the sixth time temperatures ventured into the 90s during the month since record-keeping began in 1869.

At this point in October, the normal high in the city is 69°F. But with a stubborn ridge of high pressure sitting over the region, warm air is flowing further north than it normally would at this time of year.  It is also important to note that as our climate changes, record warm days are occurring more often and the autumn season as a whole is heating up.

Credit: The Weather Gamut

September 2019: 8th Driest September on Record for NYC

September 2019 felt like a weather roller coaster in New York City. Highs ranged from a balmy 89°F to a chilly 67°F. But, with 18 out of 30 days posting above-average readings, the warmth won out in the end. The city’s mean temperature for the month was 70.4°F, which is 2.4°F above average.

In terms of precipitation, September was a month for the record books. The city only received 0.95 inches of rain in Central Park, marking its eighth driest September on record. It was also the second month in a row to deliver below-average rainfall in NYC. On average, the Big Apple gets 4.28 inches of rain for the month.