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

Last Updated - 05.15.18 (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: 05.15.18 Valid: 05.16.18 - 05.29.18
Both the RMM-based and velocity potential-based Madden-Julian Oscillation (MJO) indices depict the active phase of the MJO across the Western Hemisphere. Objective filtering of intraseasonal activity suggests the recent constructive interference between the MJO, a Kelvin wave (KW), an equatorial Rossby wave (ERW), and a low-frequency signal has contributed to increased convective activity in the vicinity of Africa. Upper-level extratropical circulation features in this general area have also been influencing the intraseasonal signal. Dynamical model guidance agrees in predicting a rapidly weakening intraseasonal signal during the next two weeks, but disagrees on how much eastward propagation of the signal occurs. The GEFS forecasts only modest eastward propagation to along the border between phases 1 and 2; the CFS and Canadian models predict a somewhat greater eastward displacement into phase 2; followed by the JMA and finally the ECMWF, which anticipates the signal to reach the border between phases 2 and 3 (Indian Ocean). Lastly, the background state continues to trend away from La Nina in the tropical Pacific, with positive near-surface heat content across nearly the entire basin, limiting low frequency impacts on the Central Pacific.

With an active KW and MJO presence over the Western Hemisphere during the past week, chances of Tropical Cyclone (TC) development were elevated over the East Pacific. Tropical depression (1E) formed near 12N/125W on May 10th, then dissipated quickly on the 11th. Over the western North Pacific, Tropical Storm Four briefly spun up near 20N/150E between May 12-13. TC development (91A) is anticipated (with moderate confidence) near the Horn of Africa during Week-1. This is due in part to the expected proximity and constructive interference of several competing modes of intraseasonal variability. A second area that is being monitored for potential TC development is on the opposite side of the globe, the eastern Gulf of Mexico. For most of the past week, deterministic and ensemble GFS runs have predicted a disturbance coming out of the western Caribbean, then tracking northward just off the west coast of Florida. Whether or not a TC develops, the primary concern is for heavy rain (high confidence) from the western Caribbean northward across the eastern Gulf of Mexico, Florida, the Southeast, the Tennessee Valley, and the mid-Atlantic during Week-1.

During Week-1, a broad area of above-average rainfall (moderate confidence) is forecast for portions of the western Indian Ocean, related to the expected complex interaction between several modes of tropical variability in addition to the TC potential. Above-average rainfall is also predicted in a band that extends southeastward from near Sri Lanka across much of the Maritime Continent region, to about the New Caledonia/Vanuatu islands of the Southwest Pacific. A large coherent region of below-average rainfall is predicted from the eastern Bay of Bengal across the South China Sea and environs, associated with the suppressed phase of the MJO.

During Week-2, there is considerable disagreement between the GEFS and ECMWF ensemble mean solutions. They agree on two small regions of above-average rainfall over the eastern Indian Ocean and for an area southwest of Hawaii. The first area appears to be related to the interaction between the MJO and an ERW, while the second area is associated with the movement of the Inter-Tropical Convergence Zone (ITCZ).

Forecast areas favoring above- or below-average rainfall over Africa are drawn in consultation with CPC's Africa Desk and may depict mesoscale to synoptic scale variability.

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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