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

Beginning June 6, 2014, CPC will be issuing an operational update of this product every Friday by 1 PM ET to further support the NWS regions. The update will only span 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 will not extend the time horizon of the product, but rather apply 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.

Last Updated - 11.28.14 (Update)

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

Global Tropical Hazards/Benefits Assessment

Global Tropics Hazards and Benefits Outlook Discussion

Updated discussion
Last Updated: 11.28.14 Valid: 11.29.14 - 12.09.14
The atmospheric circulation pattern remained consistent with an active MJO with the enhanced convection over the eastern Indian Ocean. Atmospheric Kelvin waves are also evident in some OLR measurements, and likely to contribute to the variability of convection across the tropics in the upcoming 10 days. Most models continue a moderate to strong MJO through the next two weeks, with enhanced convection moving across the Maritime Continent to the Western North Pacific. Propagation will likely be slightly slower than the models forecast, as Kelvin waves often alias into the MJO index values off the models.

Tropical Storm Sinlaku is active over the South China Sea, while Tropical Storm Two is moving southwest across the southern Indian Ocean. A moderate threat of tropical cyclone formation remains over the Western North Pacific for the remainder of Week-1. No tropical cyclone activity is likely over the eastern Pacific or the Atlantic during the upcoming 10 days. November 30 marks the official end of the Atlantic hurricane season.

The areas of above or below average rains have been adjusted to align with model guidance, guidance from other NCEP centers, and to be consistent with current forecasts. Above average rains are likely over the Caribbean, while below average rains are likely from northern Mexico to Florida, and across northern South America. Above average rains are also favored over the Philippines and portions of the Maritime Continent, with below averages rains from Papua New Guinea to the southwest Pacific.

The below average rains near Papua New Guinea are likely to give way to above average rains as the enhanced phase of the MJO propagates east across the Maritime Continent. Kelvin wave activity may contribute to a slight enhancement of convection from Central America to the Lesser Antilles.

----------------- Previous discussion follows ------------------------------------

A coherent MJO signal was evident during the previous week. The RMM index and the CPC Velocity Potential based index both indicate a strong signal, over the Indian Ocean, with eastward propagation. There are some statistical indicators that depict this signal as a confluence of other modes of variability, which many times leads to and compliment a robust MJO signal. The upper-level velocity potential spatial map depicts as Wave-2 structure, with the second area of enhanced convection likely related to a transient Kelvin wave. The low-level wind field projects strongly onto Phase 3 of the Wheeler-Hendon EOFs, with westerly anomalies from the Date Line to Africa and easterly anomalies from the Indian Ocean to the Western Pacific. The upper-level wind anomaly structure is complimentary.

Dynamical model forecasts indicate a continued propagation of a robust MJO signal across the Maritime Continent and into the Western Pacific. The transition across the Maritime Continent is an period of heightened uncertainty because of know lower skill in the models and the destructive interference with the background ENSO state. Statistical models based on wavenumber filtering are not latching onto the signal yet, but decomposing the signal into other modes. Based on recent observations and dynamical model forecasts, the MJO is likely to play a significant role in the pattern of tropical convection during the next 2 weeks.

Tropical Storm Adjali moved southward over the Southern Indian Ocean during the first day of the previous week. No other tropical cyclone activity was noted during the past week. During Week-1, the MJO and other modes of variability are likely to contribute to tropical cyclone formation over the South Indian Ocean and the Western North Pacific. A weaker signal, indicating potential for development near the southern tip of India, is present in some dynamical models, but confidence is low in any circulation reaching 35kts. During Week-2, the potential for tropical cyclone formation across the globe is too uncertain, so no areas are highlighted. The only signals during Week-2 are near the Philippines, but those appear to be tracks from a late Week-1 formation.

Above average rains are likely over the Indian Ocean and eastern equatorial Africa during Week-1, related to the MJO and a Kelvin wave. a Kelvin wave moving across the eastern Pacific is likely to enhance precipitation there, while frontal activity that interacts with tropical moisture supports above average rains from the Yucatan to the Florida, and across southern Brazil. Below average rains are likely across the Maritime continent, although confidence in that is lower than for the enhanced convection over the Indian Ocean.

During Week-2, the eastward movement of the MJO is likely to enhance rains over the western Pacific, near the Philippines and from Papua New Guinea to the Southwest Pacific, while below average convection moves into the Indian Ocean. Below average rains are also likely to overspread southern Brazil as the connection to tropical moisture is not likely to last.

Forecasts for enhanced or suppressed precipitation over Africa are based on regional scale considerations and were produced in coordination with CPC's Africa Desk.

Product Release Information

The Global Tropics Hazards and Benefits Outlook is released once per week every Tuesday at 1530 UTC (1630 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.

Product Description

The Global Tropics Hazards and Benefits Outlook is a forecast for areas with elevated odds for above- or below-median rainfall and regions where tropical cyclogenesis is favorable or unfavorable 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. 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 Author: CPC Web Team
Page last modified: 9-Jun-2014 3:37 PM EDT
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