August 2019 was another month of noticeable temperature swings in New York City. Highs ranged from an unseasonably cool 74°F to a balmy 90°F. In the end, however, the extremes balanced each other out. The city’s mean temperature for the month was 75.5°F, which is only 0.3°F above average.
In terms of precipitation, the city was unusually dry. Overall, eleven out thirty-one days posted measurable rainfall that added up to only 3.70 inches for the month. Of those eleven days, two produced strong storms that delivered more than an inch of rain each. This was the first time since March that the city received below-average rainfall. New York City, on average, gets 4.44 inches for the month.
The weather has long been a muse for artists. For Louisa McElwain (1953-2013), an American painter based in the southwest, summer storms were particularly special.
According to Evoke Contemporary, the gallery that represents her estate, McElwain was drawn to “the way the light changes and the clouds dance across the horizon ahead of the rain.” While visiting the Phoenix Art Museum recently, I came across her 2009 piece, Desert Rain God.
This large-scale oil on canvas painting captures a storm in the New Mexico desert just as a dramatic downpour is starting. These storms, largely associated with Monsoon Season in the southwest, are a vital source of moisture in the arid region.
Working outdoors, using the bed of her pick-up truck as sort of mobile studio, McElwain’s paintings aimed to capture her experience of nature. In a statement, she described her approach to painting as a “dance made to the tempo of the evolving day”. Working quickly to depict the changing effects of the atmosphere, she often used palette knives and masonry trowels to apply paint to the canvas. These tools allowed her to avoid being overly descriptive and to create an impasto effect. Most of her paintings, regardless of size, were completed in less than four hours.
Louisa McElwain’s “Desert Rain God” on display in the Phoenix Art Museum. Photo Credit: Melissa Fleming
Dealing with a cold is annoying any time of the year. During the summer, however, when you want to be outside enjoying the beautiful weather, it is especially frustrating.
According to theCenters for Disease Control and Prevention, more than 200 different viruses can cause the common cold. The two most frequently found types are rhinoviruses and enteroviruses. While present throughout the year, the prevalence of the different viruses tends to shift with the seasons. Winter colds, generally speaking, are usually the result of rhinoviruses and summer colds tend to be the product of enteroviruses.
While the weather does not cause colds, it does influence peoples’ behavior. In winter, when temperatures are chilly, people spend more time indoors where germs are more easily spread. During the warmer months of the year, people are outdoors more often, making summer colds less common than winter ones. Nevertheless, colds are spread the same way throughout the year – through close contact with infected people and contaminated surfaces.
Along with the usual sneezing, sniffling, and sore throat associated with a winter cold, certain strands of enteroviruses can also cause fever and gastrointestinal issues. Adding insult to injury, a summer cold also tends to linger a bit longer than a winter cold.
To help reduce your odds of getting sick, doctors recommend frequent hand washing and avoiding sick people.
Summer is the time of year when warm temperatures are expected. As our climate changes, however, the season is getting even hotter, especially at night.
Since 2010, according to NOAA, there have been 34% more record-warm low temperatures set than record-warm high temperatures. Nationally, summertime lows have increased an average of 1.8°F since 1895, according to an analysis by Climate Central, a nonprofit science news organization. The southwestern part of the country has seen the greatest warming, with Reno and Las Vegas, Nevada showing an increase of 16.9°F and 9.1°F respectively. Not far behind are El Paso, Texas at 7.7°F and Salt Lake City, Utah at 6.6°F.
In addition to climate change, land use issues also play a role in our warming nights. Paved surfaces hold more heat than vegetated ones, so cities tend to be hotter than rural areas, particularly during the overnight hours. This is known as the urban heat island effect.
When temperatures do not significantly cool off at night, people do not get a chance to recover from the heat of the day. This can cause serious health concerns, especially for young children, the sick, and the elderly. Warmer nights also drive up energy bills, as people with air conditioning units use them more. This in turn, if they are powered by fossil fuels, adds even more greenhouse gases to the atmosphere.
During the summer months, a change in wind direction known as a monsoon brings a major shift in the weather for the southwestern US. The season is well known for producing intense dust storms known as haboobs.
Haboobs form when thunderstorms collapse and create a strong downward flow of wind. When this downdraft of air hits the ground ahead of the storm, it blows the loose sand and soil from the desert floor high up in the air, creating a giant wall of dust. Rising quickly, haboobs often reach heights between 5000 and 8000 feet and can span out nearly 100 miles in length. Traveling at speeds ranging from 30 to 60 mph, they can cover large distances rather quickly.
Often called “black blizzards”, these storms turn day into night. Engulfing entire communities in dust, they cause respiratory problems and create serious travel hazards both in the air and on the ground. Luckily, they usually only last a few hours.
Many dry regions of the world experience haboobs, but they were first described in Sudan, along the southern edge of the Sahara Desert. As such, the word comes from Arabic and means, “blowing or blasting furiously.”
A haboob moves across Phoenix, AZ in August 2018. Credit: ChopperGuy/Twitter
Thunderstorms are impressive displays of the power of nature. However, they are also extremely dangerous.
On average, according to NOAA, lightning claims the lives of 27 people every year in the US and seriously injures hundreds more. To date in 2019, lightning has killed 12 people across ten states. The most recent victim was struck on Sunday in Richarton, ND. Local officials say the man was outside doing volunteer trail work at a recreation center when a storm moved through the area.
This type of lightning, NOAA says, strikes the US about 25 million times a year. However, 70% of lightning fatalities occur during the summer months. The season marks not only the peak of thunderstorm activity in the United States, but also the time of year when people spend more time outdoors.
According to a NWS report on lightning deaths in the US from 2006 to 2017, the vast majority of victims were men engaged in an outdoor leisure activity. Listing a variety of different pastimes at the time they were struck, fishing topped the list as the most deadly water-related recreational activity.
To avoid becoming a statistic, follow the advice of the NWS – “When thunder roars, go indoors.”
The summer phase of the North American Monsoon is underway. But what, you may wonder, are monsoons and how do they impact the United States?
While most people associate a monsoon with rain, that is only half the story. It is actually a wind system. More specifically, according to NOAA, a monsoon is “a thermally driven wind arising from differential heating between a landmass and the adjacent ocean that reverses its direction seasonally.” In fact, the word monsoon is derived from the Arabic word “mausim”, meaning seasons or wind shift.
In general, a monsoon is like a large-scale sea breeze. During the summer months, the sun heats both the land and sea, but the surface temperature of the land rises more quickly. As a result, an area of low pressure develops over the land and an area of relatively higher pressure sits over the ocean. This causes moisture-laden sea air to flow inland. As it rises and cools, it releases precipitation. In winter, this situation reverses and a dry season takes hold.
Monsoon wind systems exist in many different parts of the world, with the most famous one setting up over India and Bangladesh. In the US, we have the North American Monsoon that impacts states across the southwest. Summer temperatures in the region, which is mostly desert, can be extremely hot. Readings in the triple digits are not uncommon. This intense heat generates a thermal low near the surface and draws in moist air from the nearby Gulf of California. In addition, an area of high pressure aloft, known as the subtropical ridge, typically moves northward over the southern Plains in summer. Spinning clockwise, this shifts the winds in the area from a southwesterly to a southeasterly direction and ushers in moisture from the Gulf of Mexico. This combination of heat and moisture-rich air produces thunderstorms and heavy rainfall across the region. Monsoon rains reportedly supply 50-70% of the area’s annual precipitation.
Replenishing reservoirs and nourishing agriculture, these seasonal rains are a vital source of water in the typically arid southwest. Conversely, they can also cause a number of hazards such as flash flooding, damaging winds, dust storms, hail, and frequent lightning.
The wet phase of North American Monsoon typically runs from mid-June to the end of September.
The North American Monsoon pulls most air (green arrows) inland over the typically arid southwest region of the US. Source: NOAA/NWS
Summer vacation season is in full swing across the US. As millions of people head to beaches to have fun and beat the heat, it is important to remember that the ocean is a dynamic environment that can pose a number of hazards for swimmers. Chief among these are rip currents.
Rip currents are fast, localized channels of water moving away from the shoreline. According to NOAA, they are a result of “complex interactions between waves, currents, water levels, and nearshore bathymetry.” They can form in several different ways on any beach with breaking waves. That said, they are typically found at breaks in sandbars and along permanent structures that extend out into the water such as jetties or piers.
Moving at speeds up to 8 feet per second – which is faster than an Olympic swimmer – rip currents can easily drag unsuspecting swimmers hundreds of yards out to sea. While they will not pull anyone underwater, they can cause fatigue and panic. According to the U.S. Lifesaving Association, rip currents are responsible for 80% of all surf zone rescues. Nationally, they cause more than one hundred deaths every year.
To spot a rip current, look for a gap in the breaking waves. This is where the water is forcing its way back out to sea. The area also usually appears murky and darker than the surrounding water. On guarded beaches, red flags often indicate hazardous conditions for swimmers.
If caught in a rip current, the Red Cross recommends not trying to swim against it. Instead, they say to swim parallel to the shoreline until you are out of the current. Once free, you can start swimming back toward the beach.
Overnight lows were also mostly warmer than normal throughout the month. On July 20, the mercury only fell to 82°F, setting a new record warm low temperature for the date. In the end, the city’s mean temperature for the month was 79.6°F, which is 3.1°F above average.
It is important to note that four of the city’s ten warmest Julys on record have now occurred since 2010. The warmest was July 1999, when the average temperature for the month was 81.4°F.
This July was also above average in terms of precipitation. With several intense thunderstorms rolling through the area, a total of 5.77 inches of rain was measured in Central Park. The city, on average, gets 4.60 inches of rain for the month.
A heatwave gripped a large swath of the eastern United States this weekend. For many areas, the temperatures were extreme.
The threshold for what constitutes a heatwave varies by region, but here in the northeast, it is defined as three consecutive days with temperatures reaching 90°F or higher. In New York City, the official temperature in Central Park reached 91°F on Friday, and 95°F on both Saturday and Sunday. Overnight lows were also well above average. In fact, on Saturday, the temperature only cooled down to 82°F, tying the record warm low termperature for the date that was set in 2015.
When the humidity was factored in, it felt even hotter. The heat index ranged from 105°F-110°F.
The city’s airports, LGA and JFK, both in the borough of Queens, posted record high temperatures over the weekend, according to the National Weather Service. JFK hit 99°F on Saturday, breaking the previous record of 96°F that was set in 2013. On Sunday, LGA reached the century mark (100°F), tying the high-temperature record for the date at the site that was set in 1991.
The cause of this exceptional heat was two-fold. First, a large area of high pressure sitting over the central US was pumping hot air from the southwest toward the northeast. At the same time, a strong Bermuda High off the east coast was pumping warm, moist air from the Gulf of Mexico into the region. Together, they made it dangerously hot, which is why the NWS issued an excessive heat warning for the city. It is also why several outdoor events around the Big Apple were canceled, including the NYC Triathlon.
The hottest day ever recorded in New York City occurred on July 9, 1936, when the air temperature hit 106°F in the shade. The city’s normal high temperature this time of year is 84°F.