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.
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
The Lower East Coast Water Supply Plan
/in News, Water Conservation & QualityExcerpt from South Florida Water Management District’s Lower East Coast Water Supply Plan Update 2018, Executive Summary
The South Florida Water Management District’s (SFWMD) strategic goal for its water supply plans is to identify sufficient water supply sources and projects to meet existing and future reasonable-beneficial uses during 1-in-10-year drought conditions while sustaining water resources and related natural systems.
The 2018 Lower East Coast Water Supply Plan (LEC) is the third update to the 2000 Lower East Coast Water Supply Plan, which previously was updated in 2006 and 2013. The LEC Plan is consistent with the water supply planning requirements of Chapter 373, Florida Statutes, and presents population and water demand projections through 2040, a review of water supply issues and evaluations, and a list of water source options. It also examines local and regional water supply efforts completed and describes water resource and water supply development projects -projected to 2040.
The LEC Plan is developed in an open, public forum. Multiple meetings and workshops are held with water users, local governments, utilities, as well as agriculture, industry, and environmental representatives to solicit input, provide information about planning results, and receive comments on draft sections of the plan update.
The LEC Planning Area covers more than 6,500 square miles of southeastern Florida, including all of Palm Beach, Broward, and Miami-Dade counties, most of Monroe County, and portions of eastern Hendry and Collier counties. The LEC Planning Area includes unique and critical ecosystems such as the Everglades, Lake Okeechobee, Florida Bay, Biscayne Bay, and the Loxahatchee River. These ecosystems coexist with large agricultural areas around Lake Okeechobee and in southern Miami-Dade County, and with expansive urban areas housing 30 percent of the state’s population.
Typically, the LEC Planning Area receives abundant rainfall seasonally, with volumes exceeding human and natural system needs during wet periods. Annual precipitation averages 57 inches, with three-quarters of rainfall occurring between May and October. Water availability varies annually with periodic drought years. There is an extensive network of canals and waterworks used for water supply and flood control in the LEC Planning Area. The regional water management system plays a critical role in capturing wet season stormwater for use during dry times, moving water between natural systems, delivering water to agricultural areas and urban coastal communities, and moving excess water to tide to provide flood protection. Fresh groundwater from the surficial aquifer system and surface water from Lake Okeechobee are the primary water sources for urban, agricultural, and industrial uses in the LEC Planning Area.
Climate change and sea level rise are issues of concern, especially in coastal regions such as South Florida. South Florida is particularly vulnerable to potential changes in climate and sea level because of its location, regional variability in climate, hydrology, geology, low topography, natural resources, and dense population in coastal areas. To plan and prepare for regional climate change and sea level rise, the SFWMD is conducting research and computer modeling to better predict and reduce uncertainties, analyzing vulnerabilities in the current water management system, and developing effective adaptation strategies for the future. Coordination with other resource management entities and governments is vital to ensuring a common approach and shared information moving forward.
Successful implementation of the LEC Plan requires close coordination and collaboration with local governments, utilities, agricultural interests, and other stakeholders. This partnering should ensure water resources in the LEC Planning Area are prudently managed and available to meet future demands while also protecting the environment.
The 2018 LEC Plan Update is currently under review and scheduled for completion in 2023. Additional information on the LEC Plan Update can be found at www.sfwmd.gov/our-work/water-supply/lower-east-coast.
LWDD – Post-Storm Clean-up
/in Hurricanes, News, ResidentialFollowing a severe storm event, the Lake Worth Drainage District (LWDD) conducts immediate post-storm assessments, inspecting water control structures, canal channels and the canal rights-of-way for vegetative and other debris with the potential to negatively impact drainage.
The public can assist by reporting storm damage via our Citizen’s Reporting System located on our website at https://lwddnet.wpengine.com/storm-response. The user will be asked a few questions and a map will be provided to help identify the location of the incident in real-time. These public reports as well as LWDD staff assessments are reviewed and prioritized for vegetation removal. Priority is based on the following criteria:
Depending on the severity of the storm damage it may take several weeks before crews can address low priority incidents. Private property owners that wish to trim vegetation that has fallen or is leaning on their property from the LWDD right-of-way may do so at their discretion and expense. If access to the LWDD right-of-way is necessary to trim or remove vegetation, the property owner should receive prior approval from the LWDD for temporary access.
Any material from trimming or tree removal by the property owner must be properly disposed of by the resident or if applicable the contractor performing the work. Keep in mind that it is unlawful to place any debris in the canal or on the right-of-way in anticipation that LWDD will remove the material. Unlawful dumping will be reported to the authorities.
If fallen debris has damaged personal property, the individual property owner should contact their insurance company to submit a claim. The LWDD will not directly reimburse property owners for damage caused by acts of mother nature.
After a major storm event, debris clean-up is paramount to getting back to normal and the LWDD is committed to quick removal of hazardous flood prone debris for the safety of our residents.