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HOME > Climate & Weather Linkage > Global Tropics Benefits/Hazards

Last Updated - 11.20.18 (Routine)

GIS Ready Formats
Tropical Cyclone Formation KMZ / KML / SHP KMZ / KML / SHP
Upper Tercile Precipitation KMZ / KML / SHP KMZ / KML / SHP
Lower Tercile Precipitation KMZ / KML / SHP KMZ / KML / SHP
Above Average Temperatures KMZ / KML / SHP KMZ / KML / SHP
Below Average Temperatures KMZ / KML / SHP KMZ / KML / SHP

Global Tropics Hazards and Benefits Outlook Discussion

Last Updated: 11.20.18 Valid: 11.21.18 - 12.04.18
Analyses of recent observations across the global tropics and the RMM-based and CPC velocity potential based MJO indices show a continued active
intraseasonal signal with the enhanced phase over the Maritime Continent. The MJO propagation slowed during the past week, however, and the amplitude of the RMM index diminished. This is likely due to interactions between the MJO and an unusually strong equatorial Rossby wave (ERW) over the West Pacific. Destructive interference with the low frequency state that continues to transition towards El Nino conditions, favoring suppressed convection over the Maritime Continent also played a role. Dynamical model MJO index forecasts do not show this interruption of the signal lasting for very long. The bias corrected GEFS depicts a re-enhancement of the MJO over the West Pacific during Week-1, with eastward propagation to the Western Hemisphere during Week-2. The ECMWF is similar, albeit with reduced amplitude and increased propagation speed. Many ECMWF ensemble members show the MJO enhanced convective signal returning to the western Indian Ocean by the end of Week-2, which is on the fast end of the spectrum, but similar to the previous MJO event. Statistical guidance similarly depicts robust MJO activity, with a more canonical phase speed. Based on a general consensus of these forecasts, the MJO is anticipated to be active during the next two weeks, with a Pacific event during Week-1 transitioning to a Western Hemisphere event during Week-2. As the MJO emerges over the Pacific, it will begin constructively interfering with the low frequency signal, which may result in widespread convection along the Pacific ITCZ.

A pair of tropical depressions are currently bringing impacts to parts of Asia. Tropical Depression 32W (Toraji) is currently over the Gulf of Thailand, and is forecast to gradually weaken as it emerges over the Bay of Bengal, where conditions will become increasingly unfavorable as the suppressed phase of the MJO overspreads the Indian Ocean. Further east, Tropical Depression 33W is currently approaching the central Philippines, and is forecast to move into the South China Sea over the next few days and affect Vietnam during the middle or latter part of Week-1. The Joint Typhoon Warning Center does not anticipate substantial intensification, making heavy rainfall and flooding the primary hazards associated with this system. Tropical Depression Bouchra dissipated over the south-central Indian Ocean, and a disturbance near Sri Lanka is expected to move slowly towards the Arabian Sea over the next week, with a low chance for tropical cyclogenesis. In association with the strong ERW over the West Pacific, a low-latitude tropical depression (34W - Man-Yi) recently formed near 5N/155E. This tropical cyclone is forecast to move generally northwestward while intensifying, and may bring substantial impacts to Guam before recurving well east of the Philippines. No additional tropical cyclogenesis is anticipated during the outlook period, although some dynamical model forecasts indicate a potential for late season development over the far East Pacific.

Precipitation forecasts are based on a consensus between the CFS and ECMWF ensembles, MJO composites for Pacific and Western Hemisphere events, forecasted TC tracks, and the impacts from other modes of coherent tropical variability including the low frequency state and the West Pacific ERW. During Week-1, enhanced convection associated with tropical cyclone activity is favored over Vietnam and the adjacent South China Sea, as well as the West Pacific near Guam, with a region of suppressed convection due to subsidence in between these regions near the Philippines. Continued enhanced convection associated with the ERW is favored east of New Guinea, while suppressed convection associated with the MJO is forecast across the eastern Indian Ocean and western Maritime Continent. Constructive interference between the base state and the MJO favors widespread enhanced convection across the tropical North Pacific, reaching all the way to western South America. Additionally, enhanced convection is favored across much of western and central Brazil. A developing midlatitude storm along the east coast of the CONUS is forecast to draw in substantial tropical moisture, resulting in heavy precipitation along the Atlantic seaboard.

During Week-2, suppressed (enhanced) convection is favored over parts of the Maritime Continent (east-central Pacific, central and northeastern Brazil, and the tropical Atlantic) in association with the MJO and the low frequency state. The potential for continued westward propagation of the ERW introduces some uncertainty across the central Maritime Continent, where the MJO and low frequency state would both favor suppressed convection.

Product Release Information

The full Global Tropics Hazards and Benefits Outlook (GTH) is released once per week every Tuesday at 1730 UTC (1830 UTC when on standard time) including U.S. federal holidays. At the time of product release, there is a live briefing (available via webinar) open to all interested parties in which the latest conditions in the Tropics and the just released outlook and associated impacts are discussed. There is an opportunity to ask questions after the briefing and the briefings are available at the Live Briefing Archive and soon will be recorded.

CPC also issues an operational update of this product every Friday by 1730 UTC to further support the NWS regions. The update only spans the release period from June 1 through November 30 and a region from 120E to the Prime Meridian in longitude and from the equator to 40N in latitude. The update does not extend the time horizon of the product, but rather applies for the remaining 4 days of the previous Week-1 time period and Days 5-11 from the previous Week-2 period. This page will depict both the original and updated outlook maps as well short text outlining the forecast rationale for any changes.

Product Description

The Global Tropics Hazards and Benefits Outlook is a forecast for areas with elevated odds for above- or below-median rainfall, above- or below-normal temperatures and regions where tropical cyclogenesis is favored for the upcoming Week-1 and Week-2 time periods. The rainfall outlook is for precipitation integrated over a week and targets broad-scale patterns, not local conditions as they will be highly variable. Above(below) median rainfall forecast areas are depicted in green and yellow respectively. Above(below) normal temperature forecast areas are depicted in orange and below respectively. Favored areas for tropical development are shown in red. Two measures of confidence are indicated, high (solid) and moderate (hatched) and are currently subjective in nature and not based on an objective system. Work towards a probabilistic format of the product and so an objective measure of confidence is ongoing. The weekly verification period ranges from 00 UTC Wednesday to 00 UTC the following Wednesday.

Along with the product graphic, a written text outlook discussion is also included at release time. The narrative provides a review of the past week across the global Tropics, a description of the current climate-weather situation, the factors and reasoning behind the depicted outlook and notes on any other issues the user should be aware of. The discussion discusses the impacts in the Tropics as well as potential impacts in the Extratropics when relevant.

Product Physical Basis

The product synthesizes information and expert analysis related to climate variability across multiple time scales and from various sources, including operational climate monitoring products. The physical basis for the outlooks include El Nino-Southern Oscillation (ENSO) , the Madden-Julian Oscillation (MJO), strength and variations of the monsoon systems, other coherent subseasonal tropical variability such as atmospheric Kelvin waves (KW), Equatorial Rossby waves (ERW), African easterly waves, as well as interactions with the extratropical circulation (i.e. high latitude blocking, low-latitude frontal activity, etc.).

Product Forecast Tools

The outlook maps are currently created subjectively based on a number of forecast tools, many of which are objective. The final depiction is an assessment of these forecast tools based on a number of factors to create the final product. Work is ongoing to create an objective consolidation of some of the available forecast tools to serve as a first guess for the forecaster. Forecast tools include MJO composites, empirical and dynamical based MJO, ERW and KW forecasts, and raw dynamical model guidance from a number of modeling systems. Tropical cyclone areas are based on MJO composites and statistical and dynamical tropical cyclone forecasts as well as raw model forecast guidance.

Product Purpose

The product supports the NOAA mission in three primary ways:

  1. Assess and forecast important changes in the distribution of tropical convection (i.e., potential circulation changes across the Pacific and North America sectors) and communicate this information to NWS forecasters
  2. Provide advance notice of potential hazards related to climate, weather and hydrological events across the global tropics (including tropical cyclone risks for several NWS regions)
  3. Support various sectors of the U.S. economy (finance, energy, agriculture, water resource management) that have foreign interests.

Product Partners

The product is created through collaboration with other NOAA centers, [the National Hurricane Center (NHC) and the Central Pacific Hurricane Center (CPHC)], the Department of Defense [The Joint Typhoon Warning Center (JTWC) and the Naval Postgraduate School (NPS)], the Australian Bureau of Meteorology, Taiwan Central Weather Bureau, the State University of New York at Albany (SUNY) and the Center for Climate and Satellites (CICS), among other collaborators.

Product Users and Applications

Known users include U.S. government agencies such as NOAA [National Weather Service (NWS), River Forecast Centers (RFCs), the National Marine Fisheries Service (NMFS), the Department of the Interior (U.S. Forest Service), aid organizations (U.S. and international Red Cross, USAID), domestic and global private sector interests (financial, energy, water resource management and agricultural sectors), international weather services and various media meteorologists.

Some special applications of the product in the past include extended range predictions to support Haiti earthquake and Deepwater Horizon oil spill relief efforts as well as support for the Dynamics of the MJO (DYNAMO) scientific field campaign held from October 2011 through March 2012.

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Page last modified: 20-Jun-2018 8:16 AM EDT
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