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72-519: The Madden–Julian oscillation is characterized by an eastward progression of large regions of both enhanced and suppressed tropical rainfall, observed mainly over the Indian and Pacific Ocean. The anomalous rainfall is usually first evident over the western Indian Ocean, and remains evident as it propagates over the very warm ocean waters of the western and central tropical Pacific. This pattern of tropical rainfall generally becomes nondescript as it moves over

144-402: A Rossby-wave response to the perturbation, transforms into a coherent modon-like structure in the lower layer, which couples with a baroclinic Kelvin wave through a zone of enhanced convection and produces, at initial stages of the process, a self-sustained slowly eastward-propagating zonally- dissymmetrical quadrupolar vorticity pattern. In 2022, Rostami et al advanced their theory. By means of

216-455: A large-scale positive buoyancy anomaly, depressed anomaly, or a combination of them, as soon as this anomaly reaches a critical threshold in the presence of moist-convection at the equator. This MJO-like episode possesses a convectively coupled “hybrid structure” that consists of a “quasi equatorial modon”, with an enhanced vortex pair, and a convectively coupled baroclinic Kelvin wave (BKW), with greater phase speed than that of dipolar structure on

288-452: A new multi-layer pseudo-spectral moist-convective Thermal Rotating Shallow Water (mcTRSW) model in a full sphere, they presented a possible equatorial adjustment beyond Gill's mechanism for the genesis and dynamics of the MJO. According to this theory, an eastward propagating MJO-like structure can be generated in a self-sustained and self-propelled manner due to nonlinear relaxation (adjustment) of

360-671: A period of time, which leads to non-anomalous storm activity in each region of the globe. During the Northern Hemisphere summer season the MJO-related effects on the Indian and West African summer monsoon are well documented. MJO-related effects on the North American summer monsoon also occur, though they are relatively weaker. MJO-related impacts on the North American summer precipitation patterns are strongly linked to meridional (i.e. north–south) adjustments of

432-480: A possible mechanism to explain the genesis and backbone structure of the MJO and to converge some theories that previously seemed divergent. The MJO travels a stretch of 12,000–20,000 km over the tropical oceans, mainly over the Indo-Pacific warm pool , which has ocean temperatures generally warmer than 28 °C. This Indo-Pacific warm pool has been warming rapidly, altering the residence time of MJO over

504-541: A retrograding (i.e. westward moving) circulation pattern in the mid latitudes of the North Pacific. Typical wintertime weather anomalies preceding heavy precipitation events in the Pacific Northwest are as follows: Throughout this evolution, retrogression of the large-scale atmospheric circulation features is observed in the eastern Pacific–North American sector. Many of these events are characterized by

576-692: Is a part of the National Hurricane Center and was created in 1967. The TAFB is responsible for high seas analyses and forecasts for tropical portions of the Atlantic and Pacific between the Prime Meridian and the 140th meridian west poleward to the 30th parallel north in the northeast Pacific Ocean and the 31st parallel north in the northern Atlantic Ocean. Unlike the Hurricane Specialist Unit (HSU), TAFB

648-458: Is case-to-case variability in the amplitude and longitudinal extent of the MJO-related precipitation, so this should be viewed as a general relationship only. In 2019, Rostami and Zeitlin reported a discovery of steady, long-living, slowly eastward-moving large-scale coherent twin cyclones, so-called equatorial modons , by means of a moist-convective rotating shallow water model. Crudest barotropic features of MJO such as eastward propagation along

720-402: Is quite favorable for tropical storm development. As the MJO progresses eastward, the favored region for tropical cyclone activity also shifts eastward from the western Pacific to the eastern Pacific and finally to the Atlantic basin. An inverse relationship exists between tropical cyclone activity in the western north Pacific basin and the north Atlantic basin, however. When one basin is active,

792-676: Is staffed full-time around the year. Other responsibilities of the TAFB include satellite-derived tropical cyclone position and intensity estimates, WSR-88D radar fixes for tropical cyclones, tropical cyclone forecast support, media support, and general operational support. The Ocean Prediction Center backs up TAFB in the event of a communications outage, and vice versa. The Technology & Science Branch (TSB) develops and transitions new tools and techniques into operations for tropical weather prediction in conjunction with other government and academic entities. TSB created and continues development of

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864-495: Is suppressed. Each cycle lasts approximately 30–60 days. Because of this pattern, the Madden–Julian oscillation is also known as the 30- to 60-day oscillation , 30- to 60-day wave , or intraseasonal oscillation . Distinct patterns of lower-level and upper-level atmospheric circulation anomalies accompany the MJO-related pattern of enhanced or decreased tropical rainfall across the tropics. These circulation features extend around

936-644: The 140th meridian west poleward to the 30th parallel north in the northeast Pacific Ocean and the 31st parallel north in the northern Atlantic Ocean . The agency, which is co-located with the Miami branch of the National Weather Service , is situated on the campus of Florida International University in University Park , Miami , Florida . The NHC's Tropical Analysis and Forecast Branch (TAFB) routinely issues marine forecasts, in

1008-565: The Atlantic hurricane season and significant weather events, including snow storms, during winter and spring. Research to improve operational forecasts is done through the Hurricane Forecast Improvement Project (HFIP) and Joint Hurricane Test Bed (JHT) initiatives. During the Atlantic and northeast Pacific hurricane seasons, the Hurricane Specialist Unit (HSU) issues routine tropical weather outlooks for

1080-677: The Australian Indian Ocean Territories , all the other countries and territories in Oceania have their entire border surrounded by the Pacific Ocean . National Hurricane Center The National Hurricane Center ( NHC ) is the division of the United States' NOAA / National Weather Service responsible for tracking and predicting tropical weather systems between the Prime Meridian and

1152-588: The Automated Tropical Cyclone Forecasting (ATCF) system , used to incorporate various data and model outputs, create and update HURDAT , and to generate tropical cyclone forecasts. The TSB provides support for NHC computer and communications systems including its website. TSB maintains a number of statistical and dynamical models used in predicting both tropical cyclone behavior and associated weather conditions. The Storm Surge Unit, which develops and maintains software to forecast

1224-635: The Congo Basin and East Africa . During the major rainy seasons in East Africa (March to May and October to December), rainfall tends to be lower during when the MJO convective core is over the eastern Pacific, and higher when convection peaks over the Indian Ocean. During 'wet' phases, the normal easterly winds weaken, while during 'dry' phases, the easterly winds strengthen. An increase in frequency of MJO phases with convective activity over

1296-660: The Monthly Weather Review , and HURDAT , which is the official tropical cyclone database. Programs are dedicated to improving the accuracy of tropical cyclone forecasts from the center. The Joint Hurricane Testbed (JHT) is a joint operation between the National Oceanic and Atmospheric Administration (NOAA) and United States Weather Research Program to speed up the transfer of tropical cyclone-related research into forecast operations. Since 2001, with its annual budget of between $ 1.0 and $ 1.5 million,

1368-539: The Pacific Ocean . Countries on the western side of North America have a Pacific coast as their western or south-western border. One of the notable exceptions is Panama , where the Pacific coast is primarily on its southern border. The first Europeans to see the Pacific Ocean were able to do so by crossing the narrow Isthmus of Panama . The unique position of Panama in relation to the Pacific Ocean resulted in

1440-463: The 1950s, used aircraft to study tropical cyclones and carry out experiments on mature hurricanes through its Project Stormfury . On July 1, 1956, a National Hurricane Information Center was established in Miami, Florida, which became a warehouse for all hurricane-related information from one United States Weather Bureau office. The Miami Hurricane Warning Office (HWO) moved from Lindsey Hopkins Hotel to

1512-471: The Asian monsoon, normally during the month of July, has been attributed to the Madden–Julian oscillation after its enhanced phase moves off to the east of the region into the open tropical Pacific Ocean. Tropical cyclones occur throughout the boreal warm season (typically May–November) in both the north Pacific and the north Atlantic basins—but any given year has periods of enhanced or suppressed activity within

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1584-710: The Aviation Building 4 miles (6.4 km) to the northwest on July 1, 1958. Forecasts within the hurricane advisories were issued one day into the future in 1954 before being extended to two days into the future in 1961, three days into the future in 1964, and five days into the future in 2001. The Miami HWO moved to the campus of the University of Miami in 1964, and was referred to as the NHC in 1965. The Miami HWO tropical cyclone reports were done regularly and took on their modern format in 1964. Beginning in 1973,

1656-820: The Central Pacific Hurricane Center for the North Atlantic, Caribbean, Gulf of Mexico, and the North Pacific basin east of the International Date Line in accordance with the National Hurricane Operations Plan (NHOP). During the winter, CARCAH coordinates the Atlantic and Pacific winter storm requirements in support of the National Winter Storms Operations Plan (NWSOP). Missions are flown in advance of

1728-622: The IRE Financial Building. Male names were added into the hurricane list beginning in the 1979 season . The hurricane warning offices remained active past 1983. In 1984, the NHC was separated from the Miami Weather Service Forecast Office, which meant the meteorologist in charge at Miami was no longer in a supervisory position over the hurricane center director. By 1988, the NHC gained responsibility for eastern Pacific tropical cyclones as

1800-558: The JHT has funded 62 initiatives, with most of them being implemented operationally. The projects have had varied success, ranging from minor to significant advances in the way the NHC operates. The Hurricane Forecast Improvement Program's (HFIP) five-year goal is to lead to a 20 percent improvement within the numerical weather prediction models provided by the National Centers for Environmental Prediction to NHC by 2015 and

1872-569: The MJO also influences these conditions that facilitate or suppress tropical cyclone formation. The MJO is monitored routinely by both the USA National Hurricane Center and the USA Climate Prediction Center during the Atlantic hurricane ( tropical cyclone ) season to aid in anticipating periods of relative activity or inactivity. The MJO signal is well defined in parts of Africa including in

1944-435: The MJO enhanced activity, winds aloft are westerly. In its wake, or to the west of the enhanced rainfall area, winds aloft are easterly. These wind changes aloft are due to the divergence present over the active thunderstorms during the enhanced phase. Its direct influence can be tracked poleward as far as 30 degrees latitude from the equator in both northern and southern hemispheres, propagating outward from its origin near

2016-415: The NHC from 1995 through 2010, the hurricane specialists within the Hurricane Specialist Unit (HSU) are the chief meteorologists that predict the actions of tropical storms. The specialists work rotating eight-hour shifts from May through November, monitoring weather patterns in the Atlantic and Eastern Pacific oceans. Whenever a tropical or subtropical cyclone forms, they issue advisories every six hours until

2088-635: The NHC since 1987. On January 3, 2022, it was announced that senior hurricane specialist Stacy Stewart, who also served in the U.S. Navy reserves, retired after working at the NHC since 1999. He retired due to surgeries and post-surgical effects after being injured in Iraq. The Tropical Analysis and Forecast Branch (TAFB, formerly the Tropical Satellite Analysis and Forecast unit and the Tropical Analysis Center)

2160-632: The National Meteorological Center and Weather Prediction Center (formerly known as the Hydrometeorological Prediction Center), assumed hurricane warning/advisory responsibility at that time. This responsibility passed to regional hurricane offices in 1935, and the concept of the Atlantic hurricane season was established to keep a vigilant lookout for tropical cyclones during certain times of the year. Hurricane advisories issued every six hours by

2232-578: The National Meteorological Center duties (renamed the Hydrometeorological Prediction Center; renamed for a second time in 2013) gained advisory responsibility for tracking and publicizing inland tropical depressions. The World Meteorological Organization assumed control of the Atlantic hurricane naming list in 1977. In 1978, the NHC's offices moved off the campus of the University of Miami across U.S. Highway 1 to

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2304-703: The North Atlantic Ocean. The first hurricane warning service was set up in the 1870s from Cuba with the work of Father Benito Viñes . After his death, hurricane warning services were assumed by the United States Signal Corps and United States Weather Bureau over the next decade, first based in Jamaica in 1898 and Cuba in 1899 before shifting to Washington, D.C., in 1902. The central office in Washington, which evolved into

2376-599: The North Atlantic and eastern Pacific, making it the clearinghouse for tropical cyclone forecasts and observations occurring in these areas. If the NHC loses power or becomes incapacitated, the Central Pacific Hurricane Center backs tropical cyclone advisories and tropical weather outlooks for the northeast Pacific Ocean while the Weather Prediction Center backs up tropical cyclone advisories and tropical weather outlooks for

2448-432: The Pacific, strong MJO activity is often observed 6 to 12 months prior to the onset of an El Niño episode, but is virtually absent during the maxima of some El Niño episodes, while MJO activity is typically greater during a La Niña episode. Strong events in the Madden–Julian oscillation over a series of months in the western Pacific can speed the development of an El Niño or La Niña but usually do not in themselves lead to

2520-407: The United States as well as affected city mayors and state governors join the daily briefing call, which occurs at noon Eastern Daylight Time . As part of their annual tropical cyclone activity, the agency issues a tropical cyclone report on every tropical cyclone in the Atlantic and Eastern Pacific Ocean basins, which are available since 1958 and 1988, respectively. The report summarizes

2592-499: The Weather Prediction Center and National Hurricane Center to identify systems for the pressure maps three to seven days into the future within the tropics, and points for existing tropical cyclones six to seven days into the future. Outside of the hurricane season, the specialists concentrate on public education efforts. On April 30, 2020, senior hurricane specialist Lixion Avila retired after working at

2664-407: The amount of outgoing long wave radiation, the stronger the thunderstorm complexes, or convection, is within that region. Enhanced surface (upper level) westerly winds occur near the west (east) side of the active convection. Ocean currents, up to 100 metres (330 ft) in depth from the ocean surface, follow in phase with the east-wind component of the surface winds. In advance, or to the east, of

2736-405: The annual hurricane naming lists. Naming lists use a six-year rotation, with the deadliest or most infamous storm names retired from the rotation. For the fiscal year of 2008, the budget for the NHC was $ 6.8 million. The NHC staff has 66 members including 12 managers. The NHC is one of nine national centers which compose the National Centers for Environmental Prediction (NCEP). Known as

2808-512: The bulk of its annual precipitation . Storms in this region can last for several days or more and are often accompanied by persistent atmospheric circulation features. Of particular concern are extreme precipitation events linked to flooding . Strong evidence suggests a link between weather and climate in this region from studies that have related the El Niño Southern Oscillation to regional precipitation variability. In

2880-575: The campus of Florida International University , capable of withstanding 130 mph (210 km/h) winds. Its name was changed to the Tropical Prediction Center in 1995. After the name change to TPC, the hurricane specialists were grouped as a separate NHC unit under the Tropical Prediction Center, separating themselves from the Tropical Analysis and Forecast Branch. On October 1, 2010, the Tropical Prediction Center

2952-513: The diabatic moist-convective environment on the equator. In 2020, a study showed that the process of relaxation (adjustment) of localized large-scale pressure anomalies in the lower equatorial troposphere, generates structures strongly resembling the Madden Julian Oscillation (MJO) events, as seen in vorticity, pressure, and moisture fields. Indeed, it is demonstrated that baroclinicity and moist convection substantially change

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3024-550: The eastern Pacific might have contributed to the drying trend seen in the Congo Basin in the last few decades. There is strong year-to-year (interannual) variability in Madden–Julian oscillation activity, with long periods of strong activity followed by periods in which the oscillation is weak or absent. This interannual variability of the MJO is partly linked to the El Niño–Southern Oscillation (ENSO) cycle. In

3096-407: The equator at around 1 degree latitude, or 111 kilometres (69 mi), per day. The MJO's movement around the globe can occasionally slow or stall during the Northern Hemisphere summer and early autumn, leading to consistently enhanced rainfall for one side of the globe and consistently depressed rainfall for the other side. This can also happen early in the year. The MJO can also go quiet for

3168-454: The equator, slow phase speed, hydro-dynamical coherent structure, the convergent zone of moist-convection, are captured by Rostami and Zeitlin's modon. Having an exact solution of streamlines for internal and external regions of equatorial asymptotic modon is another feature of this structure. It is shown that such eastward-moving coherent dipolar structures can be produced during geostrophic adjustment of localized large-scale pressure anomalies in

3240-506: The form of graphics and high seas forecasts year round, with the Ocean Prediction Center having backup responsibility for this unit. The Technology and Science Branch (TSB) provides technical support for the center, which includes new infusions of technology from abroad. The Chief, Aerial Reconnaissance Coordination, All Hurricanes (CARCAH) unit tasks planes, for research and operational purposes, to tropical cyclones during

3312-685: The former Eastern Pacific Hurricane Center in San Francisco was decommissioned. In 1992, Hurricane Andrew blew the WSR-57 weather radar and the anemometer off the roof of NHC's/the Miami State Weather Forecast offices. The radar was replaced with a WSR-88D NEXRAD system in April 1993 installed near Metro Zoo , near where Hurricane Andrew made landfall. In 1995, the NHC moved into a new hurricane-resistant facility on

3384-497: The globe and are not confined to only the eastern hemisphere. The Madden–Julian oscillation moves eastward at between 4 m/s (14 km/h, 9 mph) and 8 m/s (29 km/h, 18 mph) across the tropics, crossing the Earth 's tropics in 30 to 60 days—with the active phase of the MJO tracked by the degree of outgoing long wave radiation, which is measured by infrared -sensing geostationary weather satellites . The lower

3456-546: The high-impact weather events forecast to affect the U.S., such as heavy snowfall, and at times when there is significant uncertainty within/between numerical weather prediction output. The Hurricane Liaison Team (HLT) supports hurricane response through information exchange between the NHC, the National Weather Service (NOAA/NWS), and the emergency management community. The HLT is composed of federal, state, and local emergency managers, as well as NWS meteorologists and hydrologists, who maintain open lines of communication about

3528-526: The intraseasonal time scale. Interaction of the BKW, after circumnavigating all around the equator, with a new large-scale buoyancy anomaly may contribute to excitation of a recurrent generation of the next cycle of MJO-like structure. Overall, the generated "hybrid structure” captures a few of the crudest features of the MJO, including its quadrupolar structure, convective activity, condensation patterns, vorticity field, phase speed, and westerly and easterly inflows in

3600-480: The location of extreme west coast precipitation events. Extreme events in the Pacific Northwest are accompanied by enhanced precipitation over the western tropical Pacific and the region of Southeast Asia called by meteorologists the Maritime Continent , with suppressed precipitation over the Indian Ocean and the central Pacific. As the region of interest shifts from the Pacific Northwest to California ,

3672-449: The lower and upper troposphere. Although the moisture-fed convection is a necessary condition for the ``hybrid structure” to be excited and maintained in the proposed theory in this theory, it is fundamentally different from the moisture-mode ones. Because the barotropic equatorial modon and BKW also exist in “dry” environments, while there are no similar “dry” dynamical basic structures in the moisture-mode theories. The proposed theory can be

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3744-617: The northeast Pacific and northern Atlantic oceans. When tropical storm or hurricane conditions are expected within 48 hours, the center issues watches and warnings via the news media and National Oceanic and Atmospheric Administration (NOAA) Weather Radio . Although the NHC is an agency of the United States, the World Meteorological Organization has designated it as the Regional Specialized Meteorological Center for

3816-574: The ocean initially being named the South Sea. Only four countries in South America have a Pacific coast as a part (or all) of their border. Countries and territories on the eastern , north-eastern , and south-eastern sides of Asia have a Pacific coast as a part (or all) of their border. Australia 's Pacific coast is on its eastern border. Except the Ashmore and Cartier Islands and

3888-481: The onset of a warm or cold ENSO event. However, observations suggest that the 1982-1983 El Niño developed rapidly during July 1982 in direct response to a Kelvin wave triggered by an MJO event during late May. Further, changes in the structure of the MJO with the seasonal cycle and ENSO might facilitate more substantial impacts of the MJO on ENSO. For example, the surface westerly winds associated with active MJO convection are stronger during advancement toward El Niño and

3960-483: The other is normally quiet, and vice versa. The main reason for this appears to be the phase of the MJO, which is normally in opposite modes between the two basins at any given time. While this relationship appears robust, the MJO is one of many factors that contribute to the development of tropical cyclones. For example, sea surface temperatures must be sufficiently warm and vertical wind shear must be sufficiently weak for tropical disturbances to form and persist. However,

4032-492: The precipitation pattern in the eastern tropical Pacific. A strong relationship between the leading mode of intraseasonal variability of the North American Monsoon System, the MJO and the points of origin of tropical cyclones is also present. A period of warming sea surface temperatures is found five to ten days prior to a strengthening of MJO-related precipitation across southern Asia. A break in

4104-465: The primarily cooler ocean waters of the eastern Pacific, but reappears when passing over the warmer waters over the Pacific Coast of Central America . The pattern may also occasionally reappear at low amplitude over the tropical Atlantic and higher amplitude over the Indian Ocean. The wet phase of enhanced convection and precipitation is followed by a dry phase where thunderstorm activity

4176-469: The progress and threat level of the storm with appropriate Federal, state, and local officials. The team establishes and facilitates video and/or teleconferences with the NHC, FEMA and other Federal agencies, state Emergency Operations Centers (EOCs), Weather Prediction Center (WPC), Storm Prediction Center (SPC), and River Forecast Centers (RFCs). During significant landfalling hurricanes, the President of

4248-453: The progression of the heaviest precipitation from south to north along the Pacific Northwest coast over a period of several days to more than one week. However, it is important to differentiate the individual synoptic -scale storms, which generally move west to east, from the overall large-scale pattern, which exhibits retrogression. A coherent simultaneous relationship exists between the longitudinal position of maximum MJO-related rainfall and

4320-414: The region of enhanced tropical precipitation shifts further to the east. For example, extreme rainfall events in southern California are typically accompanied by enhanced precipitation near 170°E. However, it is important to note that the overall link between the MJO and extreme west coast precipitation events weakens as the region of interest shifts southward along the west coast of the United States. There

4392-806: The regional hurricane offices began at this time. The Jacksonville hurricane warning office moved to Miami, Florida , in 1943. Tropical cyclone naming began for Atlantic tropical cyclones using the Joint Army/Navy Phonetic Alphabet by 1947. In 1950, the Miami Hurricane Warning Office began to prepare the annual hurricane season summary articles. In the 1953 Atlantic season , the United States Weather Bureau began naming storms which reach tropical storm intensity with human names. The National Hurricane Research Project , begun in

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4464-518: The scenario of the quasi-barotropic "dry" adjustment, which was established in the framework of one-layer shallow water model and consists, in the long-wave sector, in the emission of equatorial Rossby waves, with dipolar meridional structure, to the West, and of equatorial Kelvin waves, to the East. If moist convection is strong enough, a dipolar cyclonic structure, which appears in the process of adjustment as

4536-414: The season. Evidence suggests that the Madden–Julian oscillation modulates this activity (particularly for the strongest storms) by providing a large-scale environment that is favorable (or unfavorable) for development. MJO-related descending motion is not favorable for tropical storm development. However, MJO-related ascending motion is a favorable pattern for thunderstorm formation within the tropics, which

4608-464: The storm is over. Public advisories are issued more often when the storm expected to be of tropical storm or hurricane intensity threatens land. The specialists coordinate with officials in each country likely to be affected. They forecast and recommend watches and warnings. During the hurricane season, the HSU routinely issues their Tropical Weather Outlook product, which identifies areas of concern within

4680-429: The storm surge of tropical cyclones, is part of this branch. The Techniques Development and Applications Unit (TDAU) is part of TSB. The Chief, Aerial Reconnaissance Coordination, All Hurricanes (CARCAH) is a subunit of the 53d Weather Reconnaissance Squadron ( Hurricane Hunters ). CARCAH's mission is to provide a point-of-contact and to coordinate all tropical cyclone operational reconnaissance requirements at NHC and

4752-422: The surface easterly winds associated with the suppressed convective phase are stronger during advancement toward La Niña. Globally, the interannual variability of the MJO is most determined by atmospheric internal dynamics, rather than surface conditions. The strongest impacts of intraseasonal variability on the United States occur during the winter months over the western U.S. During the winter this region receives

4824-476: The synoptic history, meteorological statistics, casualties and damages, and the post-analysis best track of a storm. The reports were formally known as Preliminary Reports up until 1999. The agency maintains archives and climatological statistics on Atlantic and Pacific hurricane history, including annual reports on every tropical cyclone, a complete set of tropical cyclone advisories, digitized copies of related materials on older storms, season summaries published as

4896-406: The tropical Pacific compared to stronger warm and cold episodes. In these winters, there is a stronger link between the MJO events and extreme west coast precipitation events. The typical scenario linking the pattern of tropical rainfall associated with the MJO to extreme precipitation events in the Pacific Northwest features a progressive (i.e. eastward moving) circulation pattern in the tropics and

4968-556: The tropical Pacific, winters with weak-to-moderate cold, or La Niña, episodes or ENSO-neutral conditions are often characterized by enhanced 30- to 60-day Madden–Julian oscillation activity. A recent example is the winter of 1996–1997, which featured heavy flooding in California and in the Pacific Northwest (estimated damage costs of $ 2.0–3.0 billion at the time of the event) and a very active MJO. Such winters are also characterized by relatively small sea surface temperature anomalies in

5040-534: The tropical oceans. While the total lifespan of MJO remains in the 30–60 day timescale, its residence time has shortened over the Indian Ocean by 3–4 days (from an average of 19 days to 15 days) and increased by 5–6 days over the West Pacific (from an average of 18 days to 23 days). This change in the residence time of MJO has altered the rainfall patterns across the globe. Pacific Coast Pacific coast may be used to reference any coastline that borders

5112-476: The tropics which could develop into tropical cyclones. If systems occur outside the defined hurricane season, the HSU issues special Tropical Weather Outlooks. Backup responsibility for their northeast Pacific area resides at the Central Pacific Hurricane Center (CPHC), and vice versa if CPHC were to have communication issues. North Atlantic responsibilities are backed up by the Weather Prediction Center (WPC). Routine coordination occurs at 1700 UTC each day between

5184-418: Was renamed the NHC, and the group formerly known as the NHC became known as the Hurricane Specialist Unit (HSU). Tropical cyclone forecasting uses statistical methods based on tropical cyclone climatology, as well as methods of numerical weather prediction where computers use mathematical equations of motion to determine their movement. The World Meteorological Organization continues to create and maintain

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