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

Last Updated - 04.06.21 (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: 04.06.21 Valid: 04.07.21 - 04.20.21
The MJO strengthened at the beginning of March and it has nearly completed a global circumnavigation since that time. Based on 200-hPa velocity potential, anomalous upper-level divergence recently peaked in strength over the Indian Ocean and was the strongest in magnitude during the past six months. In addition, robust westerly 850-hPa wind anomalies overspread the western Maritime Continent by the beginning of April. These anomalous low-level westerlies are forecast to shift east to the central equatorial Pacific and further diminish and perhaps end the enhanced trade winds that have persisted due to La Nina. The dynamical model consensus depicts a continued MJO propagation eastward over the Pacific during early to mid-April. Forecast confidence remains high that the MJO continues to be a major influence on global tropical rainfall during weeks 1 and 2. Therefore, MJO precipitation composites for phases 6, 7, and 8 were used in drafting this week's outlook.

A couple of tropical cyclones (TCs) developed over the South Indian Ocean at the beginning of April and the MJO likely contributed to the genesis of these TCs. Tropical Cyclone 27S (centered at 16.2S/105.8E on Apr 7) is forecast to remain nearly stationary during the next 72 hours and then dissipate. The Joint Typhoon Warning Center calls for Tropical Cyclone Seroja, at 11.5S/118.9E, to strengthen with maximum sustained winds reaching 105 knots as it tracks southwest and parallels the Kimberley Coast of Australia. Later in week-1, TC Seroja could make landfall in Western Australia. Just to the west of these ongoing TCs, deterministic model runs continue to indicate that another TC may form early in week-1. Based on a favorable large-scale environment with the enhanced phase of the MJO crossing the West Pacific and support from model guidance, a high confidence or TC development exists over the Coral Sea during week-1. An elevated chance of TC development also is forecast across the West Pacific. Due to uncertainty on timing, a moderate confidence area covers weeks 1 and 2.

Favored areas of above and below median precipitation are based on: predicted tracks of TCs, a model consensus, and MJO precipitation composites (phases 6, 7, and 8). During the next two weeks, above average rainfall is likely across the West Pacific along with parts of the Central Pacific, including Hawaii. Above average rainfall is also favored to affect parts of the Caribbean (week-1) and northern South America (weeks 1 and 2). Once the ongoing TCs across the South Indian Ocean track poleward, below average rainfall is expected to expand east from the Indian Ocean to parts of the Maritime Continent and northern Australia by week-2.

During weeks 1 and 2, an amplifying 500-hPa trough over the eastern U.S. favors above average rainfall across the southeastern United States. This favored area of above average rainfall is also consistent with MJO precipitation composites. For hazardous weather concerns during the upcoming two weeks across the U.S. please refer to your local NWS Forecast Office, the Weather Prediction Center's Medium Range Hazards Forecast, and CPC's Week-2 U.S. Hazards Outlook. Forecasts over Africa are made in consultation with the International Desk at CPC 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 Author: CPC Web Team
Page last modified: 29-Mar-2021 3:34 PM EDT
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