Hurricane X

[Billi Plancarte]

If you are a disaster survivor, please visit FEMA.gov for up-to-date information on current disaster declarations. If you have questions about your disaster assistance application, you can call (800) 621-3362, visit disasterassistance.gov or use the FEMA mobile app.

Hurricanes are dangerous and can cause major damage from storm surge, wind damage, rip currents and flooding. They can happen along any U.S. coast or in any territory in the Atlantic or Pacific oceans. Storm surge historically is the leading cause of hurricane-related deaths in the United States.

Have several ways to receive alerts. Download the FEMA app and receive real-time alerts from the National Weather Service for up to five locations nationwide. Sign up for community alerts in your area and be aware of the Emergency Alert System (EAS) and Wireless Emergency Alert (WEA), which require no sign up.

Have enough supplies for your household, include medication, disinfectant supplies and pet supplies in your go bag or car trunk. You may not have access to these supplies for days or even weeks after a hurricane.

While hurricanes pose the greatest threat to life and property, tropical storms and depression also can be devastating. The primary hazards from tropical cyclones (which include tropical depressions, tropical storms, and hurricanes) are storm surge flooding, inland flooding from heavy rains, destructive winds, tornadoes, and high surf and rip currents.

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NOAA is forecasting a range of 17 to 25 total named storms (winds of 39 mph or higher). Of those, 8 to 13 are forecast to become hurricanes (winds of 74 mph or higher), including 4 to 7 major hurricanes (category 3, 4 or 5; with winds of 111 mph or higher). Forecasters have a 70% confidence in these ranges.

The upcoming Atlantic hurricane season is expected to have above-normal activity due to a confluence of factors, including near-record warm ocean temperatures in the Atlantic Ocean, development of La Nina conditions in the Pacific, reduced Atlantic trade winds and less wind shear, all of which tend to favor tropical storm formation.

"Severe weather and emergencies can happen at any moment, which is why individuals and communities need to be prepared today," said FEMA Deputy Administrator Erik A. Hooks. "Already, we are seeing storms move across the country that can bring additional hazards like tornadoes, flooding and hail. Taking a proactive approach to our increasingly challenging climate landscape today can make a difference in how people can recover tomorrow."

As one of the strongest El Ninos ever observed nears its end, NOAA scientists predict a quick transition to La Nina conditions, which are conducive to Atlantic hurricane activity because La Nina tends to lessen wind shear in the tropics. At the same time, abundant oceanic heat content in the tropical Atlantic Ocean and Caribbean Sea creates more energy to fuel storm development.

This hurricane season also features the potential for an above-normal west African monsoon, which can produce African easterly waves that seed some of the strongest and longer-lived Atlantic storms. Finally, light trade winds allow hurricanes to grow in strength without the disruption of strong wind shear, and also minimize ocean cooling. Human-caused climate change is warming our ocean globally and in the Atlantic basin, and melting ice on land, leading to sea level rise, which increases the risk of storm surge. Sea level rise represents a clear human influence on the damage potential from a given hurricane.

NOAA will upgrade its observing systems critical in understanding and forecasting hurricanes. These projects will provide more observations of the ocean and atmosphere in the Caribbean, the Gulf of Mexico, on the U.S. East Coast and in the tropical Atlantic.

A tropical cyclone is a generic term for a low-pressure system that formed over tropical waters (25S to 25N) with thunderstorm activity near the center of its closed, cyclonic winds. Tropical cyclones derive their energy from vertical temperature differences, are symmetrical, and have a warm core.

Currently, there are six yearly lists used in rotation found here. If a particularly damaging storm occurs, the name of that storm is retired. Storms retired in 2017 include Harvey, Irma, Maria, and Nate. If there are more storms than names on the list in a given season, an auxiliary name list is used. Lastly, if a storm happens to move across basins, it keeps the original name. The only time it is renamed is in the case that it dissipates to a tropical disturbance and then reforms.

For many years the Indian Ocean cyclones were given alphanumeric designators. The Southwest Indian Ocean tropical cyclones were first named during the 1960/1961 season. The North Indian Ocean region tropical cyclones were named as of 2006.

A rare South Atlantic storm in 2004 was post facto given the name Catarina. Another such system in 2010 was designated Anita after the fact. Starting in 2011, a name list was begun for the South Atlantic basin using mostly Brazilian designations.

The names used on the list must meet some fundamental criteria. They should be short, and readily understood when broadcast. Further the names must be culturally sensitive and not convey some unintended and potentially inflammatory meaning. The potential for misunderstanding increases when you figure that in the Atlantic basin there are twenty-four countries, reflecting an international mix of English, Spanish and French cultures.

The Automated Tropical Cyclone Forecast (ATCF) system was developed for the Joint Typhoon Warning Center in 1988. It is used by computer software to identify tropical cyclones and assist in the generation of forecast messages. In order to distinguish different tropical cyclones that might be occurring simultaneously, a distinct alphanumeric code is assigned to each cyclone once it develops a closed circulation. This code system was adopted by other warning centers in order to facilitate the passing of storm information and reduce confusion.

Oftentimes, hurricane specialists become curious about disturbances in the tropics long before they form into tropical depressions and are given a tropical cyclone number. In order to alert forecasting centers that they are investigating such a disturbance and that they wish to have it tracked by the various forecast models, the specialist will attach a 9-series number to it. The first such disturbance of the year will be designated 90, the next 91, and so on until 99. After that, they restart the sequence with 90 again. The purpose of these numbers is to clarify which disturbance they are tracking as there are often more than one happening at the same time.

Although rarer, some East Pacific names have been retired from the list. The climatology of this basin has most hurricanes moving away from the shore, so chances are rare that these storms would adversely affect people necessitating the name be retired.

A few Central Pacific names have been retired from their list. Most of them were removed for inflicting damage or adversely affecting the Hawaiian Islands. However, some have moved into the western Pacific to cause destructions, prompting their retirement.

Names retired before the 2000 season come from the name lists used by the Joint Typhoon Warning Center. Since 2000, the names removed come from the name lists used by the Japan Meteorological Agency. Most of the retired names inflicted significant damage to the nations affected.

Bess 1974 was retired after the season and replaced with Bonnie. In 1979, new name lists featuring both sexes were introduced and Bess was added back. In 1982, Bess was again retired and replaced with Brenda.

Having these conditions met is necessary but not sufficient, as many disturbances that appear to have favorable conditions do not develop. Past work (Velasco and Fritsch 1987, Chen and Frank 1993, Emanuel 1993) has identified that large thunderstorm systems (called mesoscale convective complexes) often produce an inertially stable, warm core vortex in the trailing altostratus decks of the MCC. These mesovortices have a horizontal scale of approximately 100 to 200 km [75 to 150 mi], are strongest in the mid-troposphere (5 km [3 mi]) and have no appreciable signature at the surface. Zehr (1992) hypothesizes that genesis of the tropical cyclones occurs in two stages:

stage 1 occurs when the called mesoscale convective complex produces a mesoscale vortex. Stage 2 occurs when a second blow up of convection at the mesoscale vortex initiates the intensification process of lowering central pressure and increasing swirling winds.

An upper atmospheric perturbation known as the Madden-Julian Oscillation (MJO) can travel around the globe on a time-scale of weeks. As its positive phase passes over an area it can bring favorable conditions for convection, while its negative phase can suppress it. This can affect forming tropical cyclones either giving them a boost or hindering them.

The climatic fluctuation in the Pacific Ocean known as the El Nio-Southern Oscillation (ENSO) can affect Atlantic tropical cyclone development by increasing or decreasing (depending on ENSO phase) the vertical wind shear over the western side of the basin.

When a tropical disturbance organizes into a tropical depression, the thunderstorms will begin to line up in spiral bands along the inflowing wind. The winds will begin to increase, and eventually the inner bands will close off into an eyewall, surrounding a central calm area known as the eye. This usually happens around the time wind speeds reach hurricane force. When the hurricane reaches its mature stage, eyewall replacement cycles may begin. Each cycle will be accompanied by fluctuations in the strength of the storm. Peak winds may diminish when a new eyewall replaces the old, but then re-strengthen as the new eyewall becomes established.

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