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

Last Updated - 05.21.19 (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: 05.21.19 Valid: 05.22.19 - 06.04.19
The enhanced convective phase of the MJO is currently located over the Western Hemisphere (primarily Phase 8 in RMM space), with the suppressed convective phase over the Indian Ocean and Maritime Continent (Phases 2-5). As the enhanced convection associated with the active phase of the MJO propagates slowly through Phase 8, it's in the process of coupling with enhanced El Nino-related convection (i.e., constructive interference). The strong and persistent westerly wind burst (WWB) that initiated recently over the Western Pacific continues to drive the RMM components (850-hPa and 200-hPa wind anomalies, and the Outgoing Longwave Radiation field) associated with the MJO signal. A strong easterly equatorial Rossby wave over the Central Pacific briefly interrupted the eastward propagation of the WWB. The WWB is also responsible for initiating a notable downwelling oceanic Kelvin wave, though how much this downwelling may invigorate the current El Nino is unclear.

The ECMWF model predicts eastward propagation of the MJO signal across the Western Hemisphere, Africa, and the western Indian Ocean over the next two weeks, with gradual deamplification of the signal during Week-2. The GEFS model predicts slower eastward propagation across the Western Hemisphere and Africa during the ensuing two weeks, with considerable spread apparent among ensemble members during Week-2. The CFS model predicts rapid eastward propagation of a moderate MJO across Phases 8 and 1 during Week-1, and then rapidly deamplifies and decelerates the signal in Phase 2 (over the western Indian Ocean) during Week-2. The main question at this time is how quickly the active phase of the MJO will re-emerge over the Indian Ocean.

Subtropical Depression Andrea formed during May 20th about 335 miles southwest of Bermuda, and about a week and a half prior to the official start of the Atlantic Hurricane Season (June 1st). Andrea briefly attained subtropical storm status, with peak sustained winds (May 21, 5am AST) near 40 mph. This subtropical depression is currently moving northward over the Western Atlantic, and is expected to turn northeastward later today. Interests in Bermuda should monitor the progress of this system. The National Hurricane Center (NHC) is also monitoring a disorganized area of showers and thunderstorms in association with a broad area of low pressure several hundred miles south of Guatemala and El Salvador in the far eastern Pacific. NHC predicts a moderate chance (50%) of tropical cyclone (TC) formation during the next 5 days as this disturbance meanders over the far eastern Pacific. During the past two days, GFS and ECMWF model runs have forecast TC formation over the eastern Pacific either towards the end of Week-1 or early in Week-2. Given this uncertainty, an area of TC formation (moderate confidence) is also posted for this region during the Week-2 period.

The precipitation outlooks during the next two weeks are based on influences from El Nino, model consensus among the CFS, ECMWF, and GFS models, and MJO precipitation composites for Phases 8 and 1. Above-average rainfall is predicted over the western and central tropical Indian Ocean during Weeks 1 and 2, related to a persistent low-frequency wet signal. The suppressed phase of the MJO is likely to be associated with below-average rainfall across portions of the Arabian Sea, the Indian subcontinent, the Bay of Bengal, and parts of Southeast Asia during Weeks 1 and 2. The suppressed phase of the MJO, and the MJO-related easterly anomalies currently there, are expected to delay the onset of the Indian Monsoon by perhaps two weeks. Above-average temperatures are likely to accompany the suppressed convection across much of India and Southeast Asia during the two-week period. Gradual moistening is expected over the Maritime Continent and Southeast Asia later in Week-2 and beyond, associated with the climatological onset of the Asian Monsoon. Below-average rainfall is also anticipated over parts of the Western Pacific associated with the suppressed phase of the MJO and low-frequency El Nino base state. In contrast, above-average rainfall is favored over west-central and central portions of the Pacific, due to the convectively active phase of the MJO and the low- frequency El Nino base state. Over the far eastern Pacific/Central America region, above-average rainfall is attributed to potential TC development and the expected proximity of the ITCZ. Over the Southeast, above-average temperatures and below-average rainfall are forecast, related to a mid-level ridge over the region. This is likely to be the first bona fide heat wave of the season, with maximum temperatures ranging from 95 deg F to perhaps as high as 105 deg F. The area of anticipated below- average rainfall was removed from the Southeast during Week-2, due to increasing uncertainty among model runs. Above-average rainfall is favored near the equator in the Atlantic during Week-1, attributed to the expected proximity of the ITCZ; and over the Greater Antilles (Week-2) due to the possible development of a disturbance initially over the western Caribbean. The suppressed convection favored near northern Brazil is related to the regional low-frequency El Nino dry signal.

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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Page last modified: 20-Jun-2018 8:16 AM EDT
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