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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 - 11.21.14 (Update)


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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: 11.21.14 Valid: 11.22.14 - 12.02.14
The MJO signal remained coherent during the past several days based on the RMM Index, with the enhanced convective phase propagating over the Indian Ocean. The amplitude of the CPC velocity potential index decreased, as the positive anomalies associated with the suppressed phase over the Pacific weakened and became less coherent. Although widespread Indian Ocean convection is present, convective anomalies along the equator remain smaller than expected for a canonical MJO event. Considerable uncertainty remains regarding the future evolution of the MJO as the enhanced phase reaches the Maritime Continent, where the base tropical state favors suppressed convection.

An area of low pressure embedded in the ITCZ well south of the Baja Peninsula is forecast to degenerate into an open wave and is no longer favored for tropical cyclogenesis. Additional disturbances are forecast to emerge over the Gulf of Tehuantepec during late Week-1 or Week-2, and several dynamical models depict the development of a tropical cyclone. Therefore, the moderate Week-1 tropical cyclone shape has been removed from this outlook, and the Week-2 shape has been modified to reflect the latest potential formation regions based on the model guidance. Tropical cyclogenesis is not favored during the next several days over the West Pacific, but dynamical models indicate an increasing potential for tropical cyclone development east of the Philippines during late Week-1 or Week-2.

The original forecast discussion released on 18 November 2014 follows.

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A more coherent MJO signal was evident during the previous week, with the RMM Index indicating that the enhanced phase propagated across the Western Hemisphere to the far western Indian Ocean. A coherent Wave-1 upper level zonal wind anomaly structure exists, with equatorial easterly (westerly) anomalies present across the central and eastern Pacific (South America through the Maritime Continent). The low-level wind field is less coherent over the Indian Ocean, and while the upper-level velocity potential pattern continues to exhibit a Wave-1 structure, the anomaly field has weakened during the past several days. Despite the fairly robust MJO signal indicated by the indices, equatorial convection has been weak across the Indian Ocean, with localized areas of enhanced convection displaced from the equator. Anomalous low-level equatorial easterly anomalies across Africa may be helping to inhibit widespread convection, in addition to destructive interference from the base state that favors suppressed (enhanced) convection across the Maritime Continent (western and central Pacific).

Dynamical model MJO index forecasts generally support a continued eastward propgation over the Indian Ocean during Week-1, although most models weaken the signal considerably before the enhanced phase reaches the Maritime Continent by Week-2. Additionally, the Week-1 spatial convective patterns forecast by the CFS and ECMWF are not consistent with typical MJO activity, favoring discrete areas of enhanced convection away from the equator instead of robust equatorial convective anomalies. There is also considerable uncertainty regarding the future evolution of convection across the West Pacific, with the CFS favoring a more robust subseasonal signal overcoming the base state to maintain generally suppressed convection east of New Guinea, while the ECMWF brings enhanced convection back to the West Pacific east of New Guinea by Week-2. Based on recent observations and dynamical model forecasts, therefore, the MJO is anticipated to influence the global tropical pattern during Week-1, although the robust canonical impacts of the enhanced phase are not anticipated over the Indian Ocean.

Cyclone Adjali developed over the southwestern Indian Ocean west of Diego Garcia on 16 November, and briefly reached Category-1 intensity on the Saffir-Simpson scale as it moved southeastward. Adjali is forecast to turn southward and then southwestward over the next several days, weakening substantially before approaching La Reunion Island. No other tropical cyclones developed during the previous week. During Week-1, a disturbance over the eastern Pacific south of Mexico has a moderate potential for development. Later in Week-1 or during early Week-2, dynamical models indicate a potential for a second tropical cyclone developing over the eastern Pacific. Tropical cyclogenesis is not anticipated over the northwestern Pacific during Week-1, although the potential for tropical cyclogenesis increases east of the Philippines by Week-2. Additionally, a disturbance currently between Fiji and Samoa over the southwestern Pacific has a low potential for development. Some dynamical model forecasts indicate development over the southeastern Indian Ocean during Week-2, although the potential is also too low to indicate a hazard area on this outlook.

Enhanced convection associated with Adjali is forecast over the southwestern Indian Ocean during Week-1, with little agreement among the dynamical models for any areas of large scale convection over the remainder of the Indian Ocean basin. Suppressed convection is favored over parts of the Maritime Continent and western Pacific, including parts of northern Australia, although the primary monsoon season begins during January. Enhanced convection is ongoing along the ITCZ southwest of Hawaii, and dynamical models favor this to continue during Week-1. Over the Western Hemisphere, an arctic airmass is anticipated to bring much below-normal temperatures to the southeastern CONUS, while Gulf moisture along a frontal boundary is forecast to generate enhanced rainfall. Enhanced rainfall is also anticipated along the Atlantic ITCZ north of South America. During Week-2, enhanced (suppressed) convection is anticipated over the southeastern Indian Ocean (central and southeastern Maritime Continent).

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 last modified: 9-Jun-2014 3:37 PM EDT
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