Monthly Archives: August 2017

Harvey Sets New Rainfall Record for Continental US

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Battering southeast Texas for days, Tropical Storm Harvey has produced more rainfall than any other single storm on record in the contiguous United States.

According to the NWS, 51.88 inches of rain was reported at a gauge near Mont Belvieu at Cedar Bayou, about 40 miles east of Houston. This crushes the previous record of 48 inches that was set by Tropical Storm Amelia which hit Medina, TX in 1978.

The record for the entire US, however, still stands. It was set in 1950 when Hurricane Hiki dropped 52 inches of rain on Hawaii.

Source: NWS

Harvey Unleashes Catastrophic Flooding in Houston

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Days after making landfall as a category-4 hurricane, Harvey, now a tropical storm, is still battering southeast Texas. Relentless rain has unleashed catastrophic flooding across the region, including Houston – this country’s fourth largest city.

While this devastating event is still unfolding, rainfall totals in some areas have already exceeded two feet. Dayton, TX, northeast of Houston, has reported a staggering 39.72 inches of rain since Thursday. Houston Intercontinental Airport (IAH) has posted 25.66 inches of rain so far and reported its wettest calendar day on record on Sunday with 16.07 inches.

This intense rainfall is causing the many rivers, creeks, and bayous in the metro Houston area to overflow their banks and flood homes, businesses, and major roadways – effectively paralyzing the area. Rainfall rates reached as high as 3 inches per hour on Sunday in some areas, prompting the NWS to issue a flash flood emergency – the highest level of a flood alert.

No evacuation order was issued ahead of the storm in Houston and residents were told to shelter in place. Now, thousands of high water rescues are taking place via boat and helicopter to save people trapped in their homes. The situation has many people comparing it to scenes that played out in the aftermath of Hurricane Katrina in New Orleans. The mayor of Houston, Sylvester Turner, has opened the massive George R. Brown Convention Center to be used as a shelter. As of Monday, eight storm-related deaths have been reported. But sadly, local authorities expect this number to increase as the water continues to rise.

Southeast Texas is no stranger to flooding. However, officials in Houston say this event is the worst they have seen since Tropical Storm Allison in 2001. That storm dumped more than 35 inches of rain on the metro area over the course of five days and caused $5 billion worth of damage.

Harvey, wedged between two areas of high pressure, is expected to linger over the region for several more days and dump an additional 15 to 25 inches of rain. Forecasters at the NWS say the rainfall total for this storm could reach an unprecedented 50 inches in some spots.

Eighteen counties in Texas, according to Governor Greg Abbot, have been declared federal disaster areas because of this storm.

TS Harvey caused unprecedented flooding in Houston, TX. Credit: Aryan Midas

Hurricane Harvey Hammers Texas

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Hurricane Harvey, the eighth named storm of the 2017 Atlantic Hurricane Season, made landfall in Rockport, TX late Friday night. It was the strongest storm to hit the United States in twelve years.

Coming ashore with winds measured up to 130mph, Harvey was classified as a Category-4 hurricane on the Saffir-Simpson Scale. These powerful winds along with storm surge flooding and torrential rain caused catastrophic property damage across the Texas Coastal Bend region. It also downed trees and left hundreds of thousands of people without power. To date, according to local officials, only two storm-related deaths have been reported.

Moving inland, toward Houston, Harvey weakened to a Tropical Storm on Saturday afternoon. However, despite this downgrade in wind speed, its rain bands are still drawing moisture from the Gulf of Mexico and unleashing massive amounts of precipitation. Wedged between two areas of high pressure, the storm is essentially stalled over the region. Therefore, even more flooding rain is expected over the next several days.

Harvey was the first major hurricane – category 3 or higher – to make landfall in the Lone Star State since Hurricane Carla in September 1961.

Satellite imagery from NOAA shows Hurricane Harvey along the Texas Coast. Credit: NOAA

Weather Lingo: The Brown Ocean Effect

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Tropical cyclones are fueled by warm ocean water and typically peter out over land. Sometimes, however, their lives are extended by something called the “brown ocean effect”.

This is a phenomenon where a storm derives energy from the evaporation of abundant soil moisture deposited by previous rainfall. Essentially, the saturated soil mimics the role of the ocean allowing a tropical cyclone to maintain its strength or even intensify after making landfall.

For the brown ocean effect to occur, according to a NASA funded study by Theresa Andersen and Marshall Shepherd of the University of Georgia, three criteria need to be met:

  • The soil needs to contain copious amounts of moisture.
  • Atmospheric conditions near the ground must have tropical characteristics with minimal variation in temperature.
  • Evaporation rates must be high enough to provide the storm with sufficient latent heat that it uses for fuel, at least 70 watts averaged per square meter.

Although this process supplies less energy than the ocean, it is enough to sustain a storm for a longer period than normal over land. It was first noticed in 2007 after Tropical Storm Erin made landfall in Texas and then intensified as it traveled inland. It formed an eye over Oklahoma and unleashed a massive amount of rainfall.

Storms that are impacted by the brown ocean effect maintain a warm-core and are known as Inland Tropical Cyclone Maintenance and Intensification events (TCMIs). While rare, they are most common in the US, China, and Australia.

Credit: NBC/TWC

Solar Eclipse Cools NYC by Nearly 4°F

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Monday marked the first time in decades that a total solar eclipse was visible in the continental US. The path of totality was about 70 miles wide and passed through 14 states, from Oregon to South Carolina. The rest of the country, however, saw varying degrees of a partial eclipse.

Partial Solar Eclipse 2017 seen from NYC. Credit: Melissa Fleming

Here in New York City, the magnitude was only about 72%. Nonetheless, this celestial event had a noticeable impact on the local temperature. Our weather station in mid-town Manhattan showed a drop of 3.7°F as the moon briefly obscured the afternoon sun.

The next solar eclipse that will be visible from the east coast will take place on April 8, 2024. So, hold on to those eclipse viewing glasses!

The solar eclipse peaked at 2:44 PM EDT in NYC. Credit: The Weather Gamut

The Great American Solar Eclipse of 2017

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The Great American Solar Eclipse will take place on Monday, August 21. It will be the first time that a total solar eclipse has been visible anywhere in the contiguous US since 1979 and the first event of its kind to travel across the entire continent since 1918.

A solar eclipse occurs when the moon passes between the Earth and the Sun, casting a shadow on the planet’s surface. Communities that are located in the large, but lighter penumbral shadow will see a partial eclipse. Those in the smaller, but darker umbral shadow will experience a total solar eclipse. Moving across the Earth, the umbral shadow creates what is known as a path of totality.

Credit: NASA

On Monday, this path will cross through fourteen states, from Oregon to South Carolina. However, every state in the Lower 48, as well as parts of Mexico and Canada, will see some degree of a partial eclipse.

This celestial event is also expected to affect the weather across the country. As the moon briefly obscures the Sun, temperatures are forecast to drop a few degrees. This, in turn, will also cause the winds to slacken.

When viewing this historic event, do not look directly at the Sun. Doing so will cause serious eye damage. Use special eclipse viewing glasses or a method of indirect viewing, such as a pinhole projector.

Path of Totality for Solar Eclipse 2017. Credit: GreatAmericanEclipse

July 2017: Earth’s Second Warmest on Record

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Our global temperature continued its upward trend last month with July 2017 marking the second warmest July ever recorded on this planet. Only July 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 61.89°F. That is 1.49°F above the 20th-century average. July was also the 391st 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 July, some places were particularly warm, including China, the Middle East, Australia, southern Africa, and the western United States. For the contiguous US as a whole, it was the 10th warmest July 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 July, which means there was neither an El Niño nor a La Niña to influence global weather patterns.

Year to date, the first seven months of 2017 were the second warmest such period of any year on record. Global temperature records date back to 1880.

July 2017 was the planet’s second warmest July on record. Credit: NOAA

Wearable Artwork Raises Awareness about Air Quality

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The air we breathe is not always good for us. Air pollution has been linked to a number of health concerns, from asthma to heart disease, and even cancer. To raise awareness about this issue, artist Dominque Paul has created a dress that changes colors to indicate how safe the air we breathe actually is. It’s called Air Quality Interactive Wearable.

With the exception of smog and wildfire smoke, air pollution is not something we can always see with the naked eye. To make it visible, Ms. Paul uses an Air Beam, a portable device that measures the amount of small particles (PM 2.5) in the air. These are particles that are less than 2.5 microns or 0.0001 inches in diameter. Using the Air Beam’s calculation, a color from the EPA’s Air Quality Index is assigned to the dress. These colors range from green for good air quality to yellow, orange, red, and purple, which indicate increasing levels of pollution.

Ms. Paul created this wearable art piece as part of a residency program with IDEAS xLab, a non-profit organization that uses art to raise awareness about public health. Watch the video below of her “Air Walk” in the South Bronx section of New York City.

Weather History: Ten Year Anniversary of NYC’s Strongest Tornado

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Ten years ago today, an EF2 tornado roared through New York City. It was the strongest twister on record to hit the Big Apple.

NYC Tornado of 2007. Credit: NYT

With winds measured up to 135 mph, it left a trail of destruction nine miles long from Staten Island to Brooklyn with the hardest hit neighborhoods being Bay Ridge and Sunset Park. The storm toppled trees and knocked out power to more than 4,000 customers. It damaged hundreds of cars and dozens of homes, including five that had their roofs ripped off. The storm also dumped 1.91 inches of rain in just one hour, which caused flash floods and the temporary suspension of subway service during the morning commute.

Historically, tornadoes have been rare events in NYC. In recent years, however, they have been happening more frequently. Of the eleven twisters that have touched down in the city since 1950, seven have occurred since 2003.

Note: Tornado ratings moved from the Fujita Scale (F) to the Enhanced Fujita Scale (EF) in 2007.

Weather Lingo: Invest

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The Hurricane Season officially began in June, but August is when things typically start to ramp up. It is also when the word “invest” (short for an investigative area) becomes more prevalent in weather forecasts.

When the National Hurricane Center (NHC) wants to take a closer look at an area of disturbed weather that could possibly develop into a tropical cyclone, it designates it as an invest. This opens up specialized resources, such as computer models and satellites that provide forecasters with additional data on the area in question. That said, an invest does not always become a tropical system.

More than one invest can exist at any given time, so the NHC has a special way to identify them. They are numbered from 90 to 99, followed by a letter. If the invest is in the Atlantic, the letter will be “L” and if it is in the Eastern Pacific, it will be an “E”. The numbers can be reused throughout a season, as necessary.

The Central Pacific Hurricane Center and the Joint Typhoon Warning Center follow a similar system. Letters for the basins they cover include “C” for the Central Pacific, “W” for the Western Pacific, “A” for the Arabian Sea, and “B” for the Bay of Bengal.

If an invest in any basin develops into a tropical storm, it is reclassified and given a name from that season’s pre-determined list.

An example of how the National Hurricane Center monitors and forecasts the development track of an Invest. Red is the current Invest 99L and Yellow is 90L Credit: NHC