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

Last Updated - 08.30.16 (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: 08.30.16 Valid: 08.31.16 - 09.13.16
The MJO remained weak during the past week, as other intraseasonal modes strongly influenced the pattern. The upper-level pattern does exhibit a fairly coherent Wave-1 asymmetry, suggesting an enhanched phase over the East Pacific. The OLR pattern is out of phase with the upper-level velocity potential anomalies with respect to canonical MJO activity; however, with widespread enhanced convection over the eastern Indian Ocean and the Maritime Continent. Accordingly, the RMM-based MJO index is weak, as the competing convective and upper-level components destructively interfere with each other. A robust equatorial Rossby Wave is evident in the OLR field, which is contributing to the enhanced convection over the Maritime Continent. Additionally, tropical cyclone activity and an active and northward displaced monsoon trough over the West Pacific continue to influence the overall pattern. Dynamical model RMM-based MJO index forecasts exhibit a wide range of solutions, with the GFS ensembles increasing amplitude over the Western Hemisphere by Week-2, possibly in response to tropical cyclone activity, and the ECMWF ensembles favoring the Maritime Continent. Bias-corrected versions of these model forecasts largely show a weak signal through the end of the period. Therefore, the MJO is not anticipated to play a significant role in the evolution of the global tropical convective pattern during the next two weeks.

A pair of tropical depressions (TDs) formed over the western Atlantic basin during the past week. TD-8 formed off the US South Atlantic coast on 28 August, and is currently near the North Carolina Outer Banks. A brief period of tropical storm conditions is possible along the Outer Banks before TD-8 recurves to the northeast. TD-9 formed from an easterly wave over the Florida Straits and is currently producing extremely heavy rainfall across western Cuba. Official track and intensity forecasts from the National Hurricane Center (NHC) bring TD-8 to the eastern Gulf of Mexico and across North Florida as a tropical storm. Ongoing Hurricane Gaston briefly attained Category-3 intensity on the Saffir-Simpson scale as it began recurving well east of Bermuda. Over the East Pacific, two major hurricanes developed in the past week, Lester and Madeline, and are both moving westward over the east-central Pacific. With a low shear environment and above-average SSTs in place, both storms are forecast to pass near or over the Hawaiian Islands at hurricane intensity over the next several days, with significant wind, rainfall, and wave or storm surge hazards likely, particularly for the Big Island. Elsewhere, long-lived Typhoon Lionrock made landfall as a tropical storm over northern Japan, and is forecast to continue weakening before making a second landfall over Russia's Primorsky Krai province.

Over the next several days, a tropical wave currently near the Cape Verde Islands is anticipated to encounter conditions more favorable for tropical cyclone formation as it moves westward across the Atlantic MDR. The NHC currently forecasts a 40 percent chance of TD formation over the next five days in association with this wave. Given strong dynamical model support for a tropical cyclone, a high potential for tropical cyclone formation is indicated on this outlook for the Week-1 period. Most GFS and ECMWF ensemble forecast tracks for this system bring it near or just offshore the southeastern CONUS during Week-2, with a wide range of solutions extending from the eastern Gulf of Mexico to off the coast of the Carolinas. There is also considerable uncertainty regarding the intensity of the system, should it develop. Therefore, a broad area of moderate confidence enhanced rainfall in association with this system is indicated for Week-2 extending from the Lesser Antilles through parts of the US Southeast coastline. Tropical cyclogenesis is also favored just south of Mexico over the East Pacific, although confidence is moderate. Over the West Pacific, dynamical models strongly favor tropical cyclone formation northeast of the Philippines in association with the Monsoon Trough. During Week-2, there is moderate confidence for additional tropical cyclone formation over the Atlantic MDR, due both to dynamical model guidance and climatology. There is also moderate confidence for tropical cyclone formation over the South China Sea, although development may be limited due to proximity to land.

Forecasts for regions of enhanced or suppressed rainfall were informed largely by a consensus between the CFS and ECMWF precipitation outlooks. During Week-1, suppressed (enhanced) rainfall is anticipated across western India (the Bay of Bengal and parts of Myanmar and Thailand). Further east, the Monsoon Trough is forecast to remain displaced northward with respect to climatology, resulting in enhanced rainfall extending from southeastern China through southern Japan, and suppressed rainfall across much of Southeast Asia, the South China Sea, the Phillipines, and parts of the Northwest Pacific. In part due to continued ERW influence, enhanced rainfall is forecast for the eastern Maritime Continent, including a potential for unusual off-season precipitation across central and southeastern Australia. Suppressed ITCZ precipitation is favored across the equatorial central Pacific, while enhanced precipitation along a frontal boundary is forecast for south-central and southern Brazil.

During Week-2, suppressed (enhanced) rainfall is anticipated across parts of India and the north-central Indian Ocean (eastern Indian Ocean and western Maritime Continent, the eastern Maritime Continent, and the southwestern Pacific, including American Samoa). An evolving low-frequency base state continues to favor suppressed convection across the central Pacific just north of the equator. Elsewhere, precipitation shapes on this outlook coincide with the forecasted tropical cylone activity mentioned above.

Forecasts over Africa are made in consultation with CPCs international desk, and can represent local-scale conditions in addition to global-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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Page last modified: 22-Jul-2016 3:57 PM EDT
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