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

Last Updated - 02.21.20 (Update)


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Tropical Cyclone Formation KMZ / KML / SHP KMZ / KML / SHP
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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: 02.18.20 Valid: 02.19.20 - 03.03.20
Enhanced convection in the tropics has organized and strengthened over the western Pacific over the past week. Kelvin wave activity helped shift a second center of enhanced convection from over the Indian Ocean toward the western Pacific, leading to a more coherent envelope. However, several modes of variability in the tropics have led to an obscured signal of the MJO over the past week. In early February, a renewed MJO signal emerged on the RMM index over the Maritime Continent and propagated eastward. Mid last week, interference with an equatorial Rossby wave led to a stall in the signal. This envelope of enhanced convection is forecast to continue eastward propagation in week-1, but weaken as it advances across the equatorial Pacific. Model guidance shows good agreement on the MJO falling back inside the unit circle during week-1. For week-2, models differ on the solutions for this signal, but overall, the MJO becomes incoherent and disorganized, likely not becoming a dominant forcing for the tropics toward late February.

Rossby wave activity over the Indian Ocean and western Pacific is likely to support tropical cyclone activity in the South Pacific and Indian Ocean basins during the next two weeks. Tropical Cyclone Gabekile is currently centered near 80E in the southern Indian Ocean and is expected to deteriorate over the next day or so as it interacts with a region of strong vertical wind shear. Later this week however, another tropical cyclone is forecast to emerge over the southern-central Indian Ocean, near 75E, as another equatorial Rossby wave crosses the basin. Further east, model guidance shows good agreement on cyclogenesis in the Arafura Sea, along northern Australia, over the weekend. This system will likely make landfall pretty quickly, impacting parts of the Northern Territory, Queensland and Western Australia. For the South Pacific basin, two tropical disturbances are currently being monitored by the Joint Typhoon Warning Center for tropical cyclogenesis. Confidence is high for tropical cyclone formation, supported by the MJO enhanced convective envelope as it propagates further eastward over the Pacific. During week-2, there are no strong signals in these basins for cyclogenesis. The tropical cyclones forecast to form later in the week-1 period will likely persist into week-2.

The precipitation forecasts for the tropics during the week-1 period depict the several modes of tropical variability at play. Regions of above average precipitation east of the Date Line are reflective over the enhanced convection that has organized in the western Pacific. Even though there is likely to be some decay to that organized convective center, it is forecast to push further east, causing higher than normal rainfall totals. Suppressed convection behind this convective center is likely to overspread the Maritime Continent and push into the western Pacific during week-1. Several regions of below normal rainfall are forecast in conjunction with this suppressed envelope. With the tropical cyclone activity forecast along northern Australia, a region of above normal rainfall is expected. For parts of northern Australia, an ongoing heatwave is expected to last into week-1, as forecast by the Bureau of Meteorology for Australia. Over the Indian Ocean, the forecast Rossby wave and tropical activity lead to regions of above normal rainfall in the basin. A front draping over the Gulf Coast and Southeast in the U.S. is forecast to lead to heavy rainfall along this region. For more information on this, please consult the Weather Prediction Center's 3-7 day forecast. Model consensus supports above average rainfall off the east coast of Brazil, with a forecast for drier than normal conditions to the north over Guyana, Suriname and French Guiana.

Moving into week-2, the enhanced convective envelope and corresponding suppressed envelope are forecast to shift further east. Above normal rainfall anomalies will likely extend into the eastern Pacific. Drier conditions are forecast west of and near the Date Line, as well as to remain over the Maritime Continent. With the tropical cyclone likely to form along northern Australia late in week-1, above average rainfall is forecast over parts of the region through week-2. Due to the possible impacts from this system, the forecast for above normal temperatures over parts of the Northern Territory and Western Australia does not extend into week-2. Enhanced convection appears to return to the Indian Ocean in week-2 based on the CFS, leading to regions of above average rainfall in the western part of the basin.

Forecasts over Africa are made in consultation with CPC's 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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