Tropical cyclones, known as hurricanes in the United States, develop around the globe at different times of the year. In this country, we are most impacted by the Atlantic hurricane season, which affects the North Atlantic Ocean, Caribbean Sea, and the Gulf of Mexico. It runs from June 1 through November 30.
Overall, NOAA predicts a 70% likelihood of eleven to seventeen named storms forming this season, of which five to nine could become hurricanes, including two to four major hurricanes. A major hurricane is one that is rated category 3 or higher on the Saffir-Simpson scale.
The numbers for this season’s outlook include Tropical Storm Arlene, a rare pre-season storm that developed in April.
According to NOAA, “The outlook reflects our expectation of a weak or non-existent El Niño, near or above-average sea surface temperatures across the tropical Atlantic Ocean and the Caribbean Sea, and average or weaker-than-average vertical wind shear in that same region.” El Niño conditions in the Pacific tend to cause increased wind shear in the Atlantic, which suppresses tropical development.
Regardless of the number of storms that actually form, it is important to remember that it only takes one land-falling system in your community to make it a memorable season.
Our global temperature continued its upward trend last month with April 2017 marking the second warmest April ever recorded on this planet. Only April 2016 was warmer.
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 58.32°F. That is a staggering 1.62°F above the 20th-century average. April was also the 388th 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 in April, some places were particularly warm, including Asia, Alaska, and the eastern United States. For the contiguous US as a whole, it was the 11th warmest April on NOAA’s books.
These soaring temperatures are largely attributed to the long-term trend of human-caused climate change. ENSO-neutral conditions prevailed in April, which means there was neither an El Niño nor a La Niña to influence global weather patterns.
Year to date, the first four months of 2017 were the second warmest such period of any year on record. Global temperature records date back to 1880.
April 2017 was Earth’s second warmest April on Record. Credit: NOAA
It’s official! We are having a heat wave in New York City.
The threshold for what constitutes a heat wave varies by region, but here in the northeast, it is defined as three consecutive days with temperatures reaching 90°F or higher. In Central Park, the temperature reached 90°F on Wednesday, 92°F on Thursday – setting a new record for the date – and then 91°F on Friday.
While heat waves are more common during the summer months, they have developed in the spring before. The last time one happened in May was May 2-4, 2001. The city’s earliest heat wave on record was April 16-18, 2002. This week’s event ranks as the sixth earliest, according to the NWS.
The main driver of this unseasonable heat is a stubborn Bermuda High, which is a large area of high pressure off the east coast. Spinning clockwise, it is ushering warm and humid air from the Gulf of Mexico into the region
The city’s normal high for this time of year is 72°F.
The calendar says May, but it felt more like July in New York City on Thursday. The temperature in Central Park soared to 92°F, setting a new record high for the date. The previous record of 90°F had been in place since 1936.
Wednesday was also a scorcher, producing the Big Apple’s first 90-degree day of the season. The normal high in NYC at this time of year is 71°F.
These dramatic temperatures are the result of a Bermuda High, a large area of high pressure situated off the mid-Atlantic coast. Spinning clockwise, it has been funneling very warm air from the Gulf of Mexico toward the northeast.
This type of heat can lead to the formation of ground-level ozone, which is why an air quality advisory was issued for the area. Anyone with repository concerns, like asthma, was advised to stay indoors.
While these temperatures are unseasonable, the city has seen 90° readings arrive even earlier. The earliest, according to NWS records, was April 7, 2010, when the mercury climbed to a sweltering 92°F.
If you are not quite ready for summer, fear not. Conditions more typical of May are expected to return this weekend.
Weather Whiplash for NYC. Credit: The Weather Gamut
Hurricane season in the eastern Pacific begins today.
Tropical cyclones, known as hurricanes in the United States, develop around the globe at different times of the year. In the northeastern Pacific, they tend to form between May 15 and November 30. This early start is related to the basin’s warm sea surface temperatures and relatively low wind shear.
While powerful, these Pacific storms are generally not as familiar to Americans as those that form in the Atlantic. This is because they rarely make landfall in this country. In fact, it has only happened twice. A hurricane slammed San Diego, CA in 1858 and a tropical storm battered Long Beach, CA in 1939. This low rate of occurrence is attributed to the cold water of the California Current that flows south along the west coast. Nonetheless, Pacific hurricanes can still impact the US.
Developing in the tropics, Pacific storms deteriorate as they travel north to cooler waters and in some cases over the mountains of Mexico. However, their remnants are still laden with moisture when they reach the southwestern US, where they often unleash flooding rains.
East Pacific storms can also cross into the Central Pacific and affect Hawaii. (The dividing line between the two basins is 140°W longitude.) One such storm was Hurricane Iniki in 1992, the worst hurricane in the state’s history. With wind speeds measured up to 145mph, it was rated category-4 on the Saffir-Simpson scale.
This year, the eastern Pacific hurricane season got off to a record early start, with the development of Tropical Storm Adrian on May 9. No other storm in the basin has formed earlier during the satellite era.
An unseasonable nor’easter soaked the northeastern US this Mother’s Day weekend. Heavy rain and gusty winds were reported across the region.
Here in New York City, 1.61 inches of rain fell in Central Park. This impressive total was only a few one-hundredths on an inch shy of the daily record of 1.66 inches that was set in 1971.
This storm also marked the second consecutive wet weekend for the Big Apple. Last Friday, a record-shattering 3.02 inches of rain came down in just a few hours. Between these two storms, the city has already received more precipitation than it typically sees for the entire month of May.
With an area of low pressure intensifying as it traveled north along the Atlantic coast, this storm was a textbook nor’easter. While this type of storm is more common during the fall and winter months, they can develop any time of the year.
Satellite view of the unseasonable May nor’easter. Credit: NOAA
In the northeastern United States, nor’easters are well known for producing heavy precipitation, strong winds, and coastal flooding. Despite approaching the region from the south, they take their name from the steady northeasterly winds that blow in off the ocean.
Nor’easters can occur any time of the year but are most common between November and March. This is because the cold air that dips south in a jet stream trough during fall and winter often meets warmer air moving north over the Gulf Stream, which is just off the east coast. This contrast in temperature strengthens the storms. That said, there are a few different ways in which they can develop.
The first is called a “Miller Type-A” storm and is considered the “classic” nor’easter. These occur when an area of low pressure develops along the Gulf Coast or Atlantic Coast and intensifies as it tracks northward along the eastern seaboard.
The second type originates in the mid-west and is known as a “Miller Type-B” storm. Traveling east, these low-pressure systems weaken when they run into the Appalachian Mountains and transfer their energy to the coast. Often called a “center jump”, this transfer strengthens or creates a secondary low on the lee side of the mountains, which then moves northward. These types of storms are notoriously difficult to forecast as everything depends on the timing and location of the energy transfer between the two lows.
Both Miller “types” are named after James E. Miller, an atmospheric scientist who studied storm formation in the Atlantic coastal region during the mid 20th century.
Typical Miller Type A and B storm tracks. Credit: NOAA
It was a thrill to be asked back to The Weather Channel’s WUTV show on Friday. As a New York City-based contributor to their PWS network, we discussed the record rainfall that swept through the city and the numerous flooding situations it caused.
The show, which dives into the science behind different weather events, airs weeknights from 6 to 8 PM EST on The Weather Channel.
Weather Gamut writer, Melissa Fleming, talks about record rainfall in NYC on WUTV. May 5, 2017. Credit: TWC and Melissa Fleming.
An intense rainstorm swept through New York City on Friday afternoon. With bands of heavy downpours, it unleashed more than half a month’s worth of rain in just a few hours.
According to the NWS, 3.02 inches of rain was measured in Central Park, setting a new record for the date. The previous record of 1.55 inches had been in place since 1871. On average, the Big Apple gets 4.19 inches of rain for the entire month of May.
The heavy rain disrupted travel across the city, with flash flood warnings issued in all five boroughs. 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.
Flooding on NYC’s West Side Highway. Credit: New York Patch
Transitioning to spring, April was a month of wild temperature swings in New York City. We had highs that ranged from a chilly 48°F to a summer-like 87°F. However, with 19 out of 30 days posting above average readings, the warmth won out in the end.
In terms of precipitation, April’s famous showers were slightly below normal with 3.84 inches of rain measured in Central Park. But of this total, the vast majority (74%) came down on three different, but very wet, days. The city usually sees 4.50 inches of rain for the month.