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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 - 07.03.15 (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: 07.03.15 Valid: 07.04.15 - 07.14.15
During the past several days, an extremely strong anomalous westerly wind burst, partly caused by tropical cyclone activity, developed over the equatorial western Pacific just west of the Date Line. This feature helped contribute to a very strong Phase-7 projection on the RMM MJO index, more than three standard deviations outside the circle. Dynamical models favor further amplification of the RMM Index, followed by gradual weakening, with the ECMWF continuing to depict further eastward propagation of the intraseasonal signal, while the GFS maintains a more stationary pattern.

Two additional tropical cyclones developed over the northwestern Pacific during the past several days, both within the high confidence formation shape depicted on the 30 June GTH Outlook. Tropical Storm Linfa is currently east of the Philippines, and may make landfall over Luzon over the next several days. Tropical Depression 11W formed near 170E and 10N, and is forecast to move westward or west-northwestward while intensifying. Dynamical models do not favor additional tropical cyclogenesis over the western Pacific, so the TC formation shape was removed from the updated outlook. The enhanced precipitation shape was modified based on the latest tropical cyclone track forecasts.

The National Hurricane Center is currently monitoring two systems that have a potential to develop over the southwestern portion of the East Pacific basin during the next 5 days. Additionally, the Central Pacific Hurricane Center is monitoring a system near 140W and 10N that has a low potential for development during the next 48 hours. For the updated GTH Outlook, a broad high confidence TC formation shape encompasses all three areas of potential development. A moderate confidence TC shape was maintained south of Hawaii for Week-2, and dynamical models, the MJO, and the El Nino base state all favor new potential cyclogenesis over the eastern Pacific during Week-2.

Wet and dry shapes were modified based on the latest guidance. Locally heavy rainfall is possible over monsoon regions of New Mexico, eastern Arizona, and northwestern Mexico. Additionally, suppressed convection is favored over the northeastern Caribbean during Week-2, which may exacerbate drought conditions over Puerto Rico.

The original discussion released on 30 June 2015 follows.


The MJO remained active during the past week, with the enhanced convective phase now over the western Pacific, as indicated by both the RMM and CPC velocity potential based MJO indices. The spatial pattern of upper level velocity potential anomalies continues to exhibit a robust and coherent Wave-1 structure. The MJO is beginning to constructively interfere with the El Nino base state, and Kelvin Wave (KW) activity over the Pacific ahead of the MJO convective envelope has resulted in strong pulses of enhanced convection.

Dynamical models, including the GEFS and ECMWF ensemble systems, indicate strong amplification of the RMM index over the western Pacific. This amplitude is primarily associated with a strong westerly wind burst near the Date Line, which may be further enhanced during Week-1 by several tropical cyclones over the western Pacific, including existing twin cyclones straddling the equator near 160E. The GFS and CFS depict little further eastward propgation of the signal, instead favoring a gradual weakening of the intraseasonal convective anomalies towards the base state. The ECMWF maintains more eastward propagation of the MJO signal, with the enhanced phase approaching the eastern Pacific by the end of Week-2. The extent of the eastward propagation of the MJO signal will play a substantial role in the potential for tropical cyclogenesis over the eastern Pacific, and even the Atlantic, during the next several weeks.

Two tropical cyclones developed on 30 June over the western Pacific near 160E: Tropical Depression 09W (Chan-hom) north of the equator, and Tropical Depression 25 south of the equator. Chan-hom is forecast to gradually intensify as it moves west-northwestward, potentially affecting Guam towards the end of the Week-1 period as a typhoon. TD 25 is forecast to modestly strengthen, but remain a tropical storm as it moves generally southward across the Solomon Islands. During Week-1, additional tropical cyclogenesis is favored across the northwestern Pacific, with a potential for a highly active pattern during the period. There is a moderate potential early in the period for two additional tropical cyclones to form between Chan-hom's current position and the Philippines during the next several days, and there is a higher potential for additional tropical cyclone formation between 155E and the Date Line. Later in the Week-1 period through Week-2, additional KW activity constructively interfering with the El Nino may promote tropical cyclone formation south or southeast of Hawaii. Additionally, relaxing vertical shear and KW activity may increase the potential for tropical cyclogenesis over southwestern portions of the East Pacific basin towards the end of Week-2.

During Week-1, dynamical models, MJO composites, and the base state all favor suppressed convection across southern portions of South Asia, parts of the Indian Ocean, and along the equator across the Maritime Continent. Suppressed convection is also favored across parts of the eastern Pacific and the adjacent Mexico and Central American coastal areas. Widespread enhanced convection is favored from the South China sea and northwestern Pacific, as well as the equatorial central and east-central Pacific. Enhanced convection is also favored across northwestern Mexico, and may impact parts of the southwestern U.S.

During Week-2, the MJO, El Nino, and any subsidence surrounding potential tropical cyclones all favor a continuation of suppressed convection across much of the Maritime Continent. Enhanced convection, associated with frontal activity and potential tropical cyclones, is forecast across much of the South China Sea, Philippines, and northwestern Pacific south of Japan. Enhanced convection associated with El Nino is anticipated to continue along and north of the equator from the Date Line eastward. Continued enhancement of the Monsoon across northwestern Mexico and the southwestern U.S. is also forecast.

Forecasts for enhanced or suppressed rainfall across Africa are provided in collaboration with CPC's Africa Desk and are based on regional scale anomaly features.

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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