El Niño and La Niña are climate phenomena that originate in the equatorial Pacific Ocean. These phenomena can have wide-ranging effects on weather around the world.
Never occurring simultaneously and sometimes not at all, El Niño and La Niña are the opposite phases of the El Niño-Southern Oscillation, or ENSO. ENSO describes the fluctuation of two elements, temperature and pressure.
The temperature component of ENSO refers to ocean water temperature. When sea-surface temperatures are above average by about 1 degree Fahrenheit or more, El Niño can develop. When temperatures are below average, La Niña can form. When temperatures are at or near average neither develops. This is called ENSO-neutral.
The air pressure component refers to the difference in air pressure between the western and eastern parts of the equatorial Pacific. Scientists use readings from Darwin, on the north-central coast of Australia, and from Tahiti, more than 5,000 miles to the east. When the pressure is lower than normal in Tahiti and higher than normal in Darwin, conditions favor the development of El Niño. When the opposite occurs, La Niña may develop.
The two components, temperature and pressure, are strongly related, and conditions of both must be right for either El Niño or La Niña to form. For example, if sea-surface temperatures favor El Niño but air pressure conditions do not, El Niño will not develop.
Scientists are not sure exactly what starts the process. But from time to time, air pressure conditions change over the equatorial Pacific, affecting the trade winds, which normally blow from east to west. The winds act on the surface of the water pushing it along. If the trade winds strengthen, as occurs during La Niña, more warm water is pushed westward. And in the eastern Pacific cold, deep water rises-up to replace it. If the trade winds weaken, as happens during El Niño, less water moves westward and less cold water rises, and the central and eastern Pacific warm up more than usual.
A huge mass of warm water in the ocean transfers a lot of heat high into the atmosphere through convection. Convection is when warm, moist air rises from the sea surface and forms storms. The heat in turn affects atmospheric circulation, both in the north-south direction and east-west.
The location of the convection is important. In El Niño, because the warm water stays in the eastern Pacific, the convection occurs there. In La Niña, the eastern Pacific stays colder, and the convection occurs much farther to the west.
The changes in atmospheric circulation can result in changes in weather in various parts of the world, what meteorologists call teleconnections. Much of this is related to the position of the jet stream, the high-altitude winds that sweep across the planet from west to east.
In El Niño, the jet stream tends to shift to the south. That can bring rain and cooler conditions to much of the Southern United States, and warmer conditions to parts of the North. Elsewhere, El Niño can create warm, dry conditions in Asia, Australia and the Indian subcontinent. Parts of Africa and South America can be affected as well.
In La Niña, the jet stream shifts northward. That can lead to warm and dry conditions in the Southern United States, and cooler, wetter weather in parts of the North, especially the Pacific Northwest. Parts of Australia and Asia can be wetter than normal.
In the U.S., the National Oceanic and Atmospheric Administration (NOAA) declares when an El Niño or La Niña event begins. Weather forecasters will talk about how a developing El Niño, for example, may bring a wetter, or perhaps a drier, winter. Or they may describe how an established La Niña is making for a more active hurricane season. It’s important to note that these are just typical effects. El Niño and La Niña sometimes don’t follow the expected patterns. Also, strength matters and a strong El Niño, as measured by how high sea-surface temperatures are above normal, will have greater effect.
How do El Niño and La Niña effect the Atlantic Hurricane season? The chances for the continental U.S. and the Caribbean Islands to experience a hurricane substantially increase during La Niña and decrease during El Niño.
El Niño produces stronger westerly winds at upper levels of the atmosphere across the tropical Atlantic. This increases the vertical wind shear, basically shearing the tops from developing storms before a healthy circulation can form. El Niño events generally suppress Atlantic hurricane activity so fewer hurricanes than normal form in the Atlantic during August to October, the peak of Atlantic hurricane season.
During La Niña, westerly winds high in the atmosphere weaken. This results in an expanded area of low vertical wind shear, allowing more Atlantic hurricanes to develop. La Niña not only increases the number of hurricanes that develop but may allow stronger hurricanes to form.
El Niño and La Niña also influence where Atlantic hurricanes develop. During La Niña, more hurricanes form in the deep Tropics from weather disturbances that originate over North Africa. These systems have a much greater likelihood of becoming major hurricanes, and of eventually reaching the U.S. and the Caribbean Islands.
Although hurricanes occur more often during La Niña episodes, significant tropical weather events have occurred during the neutral phase. For example, the record shattering 2005 hurricane season that included Katrina and Rita occurred during the neutral phase. And in 1992, Hurricane Andrew, the most destructive United States hurricane of record, made landfall along the Gulf coast during a neutral phase of the El Niño-Southern Oscillation.
Podcast -Tommy Strowd on Water Supply
/in Flood Control, News, ResidentialExecutive Director Tommy Strowd’s appearance on the Friends of Delray Podcast where he discusses the future of water supply in our area.
Watch Podcast
Harry Raucher Retires From Board
/in NewsHarry Raucher retired from the LWDD Board of Supervisors after serving 11 years, with 5 years as chairman. LWDD management and staff are grateful for his leadership and vision over the years. We wish Harry and his wife Barbara all the best on their new adventure. Carrie Parker Hill, a resident of Boynton Beach, was appointed interim Supervisor to complete his term which ends January 2023. Read the Board Proclamation passed on October 12, 2002, in honor of Raucher’s service below.
Proclamation In Honor Of
HARRY RAUCHER
Whereas, the Lake Worth Drainage District is a public body and political subdivision of the State of Florida, which owns rights-of-way and manages over five hundred miles of drainage canals within its jurisdictional boundary; and
Whereas, HARRY RAUCHER was appointed to the Lake Worth Drainage District Board of Supervisors on May 11, 2011, and subsequently elected by the landowners within the Lake Worth Drainage District, and has faithfully served the Lake Worth Drainage District over eleven years; and
Whereas, HARRY RAUCHER during his tenure as Board Supervisor has demonstrated extraordinary leadership and facilitated many significant accomplishments including but not limited to:
Whereas HARRY RAUCHER is retiring from service as Board Supervisor of the Lake Worth Drainage District on the October 12, 2022, and the Board of Supervisors and employees desire to honor, recognize and bestow upon HARRY RAUCHER the deserved appropriate accolades for his service.
Now, Therefore Be It Resolved, that the Board of Supervisors of the Lake Worth Drainage District, does hereby bestow special recognition to HARRY RAUCHER for his exceptional leadership and service to the Lake Worth Drainage District.
El Niño and La Niña Explained
/in Hurricanes, NewsEl Niño and La Niña are climate phenomena that originate in the equatorial Pacific Ocean. These phenomena can have wide-ranging effects on weather around the world.
Never occurring simultaneously and sometimes not at all, El Niño and La Niña are the opposite phases of the El Niño-Southern Oscillation, or ENSO. ENSO describes the fluctuation of two elements, temperature and pressure.
The temperature component of ENSO refers to ocean water temperature. When sea-surface temperatures are above average by about 1 degree Fahrenheit or more, El Niño can develop. When temperatures are below average, La Niña can form. When temperatures are at or near average neither develops. This is called ENSO-neutral.
The air pressure component refers to the difference in air pressure between the western and eastern parts of the equatorial Pacific. Scientists use readings from Darwin, on the north-central coast of Australia, and from Tahiti, more than 5,000 miles to the east. When the pressure is lower than normal in Tahiti and higher than normal in Darwin, conditions favor the development of El Niño. When the opposite occurs, La Niña may develop.
The two components, temperature and pressure, are strongly related, and conditions of both must be right for either El Niño or La Niña to form. For example, if sea-surface temperatures favor El Niño but air pressure conditions do not, El Niño will not develop.
Scientists are not sure exactly what starts the process. But from time to time, air pressure conditions change over the equatorial Pacific, affecting the trade winds, which normally blow from east to west. The winds act on the surface of the water pushing it along. If the trade winds strengthen, as occurs during La Niña, more warm water is pushed westward. And in the eastern Pacific cold, deep water rises-up to replace it. If the trade winds weaken, as happens during El Niño, less water moves westward and less cold water rises, and the central and eastern Pacific warm up more than usual.
A huge mass of warm water in the ocean transfers a lot of heat high into the atmosphere through convection. Convection is when warm, moist air rises from the sea surface and forms storms. The heat in turn affects atmospheric circulation, both in the north-south direction and east-west.
The location of the convection is important. In El Niño, because the warm water stays in the eastern Pacific, the convection occurs there. In La Niña, the eastern Pacific stays colder, and the convection occurs much farther to the west.
The changes in atmospheric circulation can result in changes in weather in various parts of the world, what meteorologists call teleconnections. Much of this is related to the position of the jet stream, the high-altitude winds that sweep across the planet from west to east.
In El Niño, the jet stream tends to shift to the south. That can bring rain and cooler conditions to much of the Southern United States, and warmer conditions to parts of the North. Elsewhere, El Niño can create warm, dry conditions in Asia, Australia and the Indian subcontinent. Parts of Africa and South America can be affected as well.
In La Niña, the jet stream shifts northward. That can lead to warm and dry conditions in the Southern United States, and cooler, wetter weather in parts of the North, especially the Pacific Northwest. Parts of Australia and Asia can be wetter than normal.
In the U.S., the National Oceanic and Atmospheric Administration (NOAA) declares when an El Niño or La Niña event begins. Weather forecasters will talk about how a developing El Niño, for example, may bring a wetter, or perhaps a drier, winter. Or they may describe how an established La Niña is making for a more active hurricane season. It’s important to note that these are just typical effects. El Niño and La Niña sometimes don’t follow the expected patterns. Also, strength matters and a strong El Niño, as measured by how high sea-surface temperatures are above normal, will have greater effect.
How do El Niño and La Niña effect the Atlantic Hurricane season? The chances for the continental U.S. and the Caribbean Islands to experience a hurricane substantially increase during La Niña and decrease during El Niño.
El Niño produces stronger westerly winds at upper levels of the atmosphere across the tropical Atlantic. This increases the vertical wind shear, basically shearing the tops from developing storms before a healthy circulation can form. El Niño events generally suppress Atlantic hurricane activity so fewer hurricanes than normal form in the Atlantic during August to October, the peak of Atlantic hurricane season.
During La Niña, westerly winds high in the atmosphere weaken. This results in an expanded area of low vertical wind shear, allowing more Atlantic hurricanes to develop. La Niña not only increases the number of hurricanes that develop but may allow stronger hurricanes to form.
El Niño and La Niña also influence where Atlantic hurricanes develop. During La Niña, more hurricanes form in the deep Tropics from weather disturbances that originate over North Africa. These systems have a much greater likelihood of becoming major hurricanes, and of eventually reaching the U.S. and the Caribbean Islands.
Although hurricanes occur more often during La Niña episodes, significant tropical weather events have occurred during the neutral phase. For example, the record shattering 2005 hurricane season that included Katrina and Rita occurred during the neutral phase. And in 1992, Hurricane Andrew, the most destructive United States hurricane of record, made landfall along the Gulf coast during a neutral phase of the El Niño-Southern Oscillation.
Prevent Flooding – Adopt A Storm Drain
/in Flood Control, News, ResidentialEveryone knows that trash is not good for our waterways, but many people unwittingly contribute to water pollution because they do not understand that “natural” trash like leaves, grass clippings and pet waste can become pollutants when they enter the water. Additionally, storm drains are part of the local flood control system helping to move storm water away from homes and businesses. They act as a conduit discharging storm water into local stormwater ponds and drainage canals.
When organic debris like leaves and grass wash down a storm drain, they decompose and release nutrients like phosphorous and nitrogen. These nutrients are food for algae and other aquatic plants. Additionally, people can add to the nutrient load by applying fertilizers which can wash down storm drains after a rain.
Debris blocking storm drains can be a local flooding hazard. Even an average afternoon rainstorm can cause local street flooding if the water has nowhere to go. Just a small number of organic debris and trash on top of a drain grate can reduce drainage capacity. By keeping the storm drain clear of debris, it can function as designed allowing storm water to flow away from your home and discharge into flood control canals.
Some helpful tools for cleaning a storm drain include: a broom, a rake, a trash grabber, gloves, an orange cone and/or safety vest, a shovel or dustpan and a pail or yard waste bag. Never remove the grate or otherwise attempt to clean inside the catch basin. Clean only the surface of the storm drain grate and the area around it. If the drain seems to be plugged or have any problems, contact your community board/property manager or local municipality to address the issue.
Adopting a storm drain only takes a small amount of your time. Let friends and neighbors know about your commitment and invite them to adopt a storm drain too. When we all sweep up, rake up and pick up, we protect our properties and waterways.
The Chance Your Home May Flood
/in Flood Control, News, ResidentialWithin the Lake Worth Drainage District (LWDD) boundary, some homes and businesses are constructed in areas known as the 1 in 100-year flood plain but have experienced multiple floods in the same year. The assumption that if their area has experienced a 1 in 100-year flood, then for the next 99 years they do not have to worry about flooding is not correct. While it’s unlikely that two large storms will happen in close succession, history has demonstrated that it is possible.
Confused by the term 1 in 100-year flood, many people begin to wonder what their flood risk really is. The definition of a 1 in 100-year flood is a flood that has a 1% chance of occurring in any given year. Understanding your flood risk can be a complex process, but the hydrologists at the U.S. Geological Survey (USGS) are striving to communicate risk more effectively, in part by transitioning away from the term 1 in 100-year flood and instead referencing multiple year flooding probabilities. For example, a home in the 1 in 100-year flood plain, may be better understood as a home with a 26% chance it will flood over the course of a 30-year mortgage. Providing a clearer understanding of the probability of flood risk allows decisions to be made to better protect people and buildings.
The USGS has published a flyer discussing in detail the probability of flood risk. You can download a copy at https://pubs.usgs.gov/gip/106/pdf/100-year-flood-handout-042610.pdf