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GTH Outlook Map and Data
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Last Updated -
04/15/25
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GTH Outlook Discussion
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Last Updated -
04/15/25
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Valid -
04/23/25 - 05/06/25
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The Madden Julian Oscillation (MJO) has been inactive since late March with the RMM-based index meandering within the unit circle for the past couple weeks, and a convectively coupled Kevin Wave (CCKW) likely to spread enhanced convection across the eastern Pacific by next week. ENSO-neutral conditions have returned to the tropical Pacific further limiting the tropical forcing. The ECENS and GEFS ensembles indicate a re-emergence of the MJO across the Western Pacific by week-2, but this is more likely tied to an enhanced low frequency convective state developing over the region, with limited eastward propagation. Suppressed convective activity is forecast upstream over the Indian Ocean.
Despite the lack of MJO, and a decreasing climatology for tropical cyclogenesis, tropical cyclone (TC) formation was observed in the southern Indian Ocean and South Pacific during the past week. Tropical Cyclone Errol developed on April 11 over the Timor Sea (11 deg S, 128 deg E) and has been moving southwestward offshore the Kimberley Coast of Australia. Tropical Cyclone Tam formed on April 14 near Vanuatu (15 deg S, 168 deg E) and is tracking southward. Additional TC formations are possible in week-1, with Invests 97P and 99S located over the Gulf of Carpentaria and southern Indian Ocean respectively. By week-2, the increasing MJO signal across phases 6 and 7, along with reduced wind shear, support continued enhanced chances for additional TC development, with a 40-60 percent chance highlighted from the Timor Sea eastward through the Coral Sea. A broader 20-40 percent area stretches from off the northwest Australia coast to Vanuatu. By week-3, climatology wanes significantly, and the MJO may shift more into phases 7 and 8. This would favor reduced confidence for TC formation further west, but continued enhanced TC activity is not ruled out across the Gulf of Carpentaria and Coral Sea where 20-40 percent chances are posted.
Across the western north Pacific, individual GEFS and ECENS ensemble members depict surface low pressure tracking to the east of the Philippines tied to the enhanced convective envelope developing over the region. There is some uncertainty regarding the tropical nature of this system versus frontal influence. However, given the favorable convective environment aloft and support from MJO composites, a 20-40 percent chance for TC formation is highlighted over the area. Similar dynamics may continue into week-3 given the nearly stationary convective envelope. However, the uncertainty combined with the longer lead precludes continuing the 20-40 percent risk area, and this time frame will be reassessed next week.
Forecasts for enhanced and suppressed precipitation are mainly based on a consolidated skill weighted blend of GEFS, CFSv2, and ECMWF ensemble systems, anticipated TC tracks, with some consideration of historical MJO composites for Mar-May for phases 6-8. Less emphasis is given to ENSO given the return to neutral conditions. Above-normal rainfall is forecast across the Western Pacific and Maritime Continent, with below-normal rainfall upstream over the Indian Ocean. Surface low pressure across the central Pacific may bring some enhanced rainfall in the vicinity of Hawaii. Above-normal temperatures are favored over parts of India, with daytime maximum temperatures possibly exceeding 100 deg F during week-2. Above-normal temperatures are also predicted across the south-central and southeastern U.S.
Forecasts for Africa are made in coordination with the CPC International Desk. For hazardous weather concerns in your area for the next two weeks, please refer to your local NWS office, the Medium Range Hazards Outlook issued by the Weather Prediction Center, and the CPC Week-2 Hazards Outlook.
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Product Release Information
The Global Tropics Hazards 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 Google Meet) open to all stakeholders where the latest conditions and the newly
released outlook are shared with the opportunity to ask questions. Folks that are interested in learning more or attending these briefings should contact
Jon.Gottschalck@noaa.gov, Scott.Handel@noaa.gov, Adam.Allgood@noaa.gov and Nicholas.Novella@noaa.gov for the required information. Each weekly outlook and GTH release briefing is
Archived and available on the website.
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Product Description
The Global Tropics Hazards Outlook is a probabilistic forecast for areas with elevated probabilities for above- or below-median rainfall, above- or below-normal
temperatures and regions where tropical cyclogenesis is favored for the upcoming Week-2 and Week-3 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 brown respectively. Above (below) normal temperature forecast areas are depicted in orange and blue respectively. Favored areas for tropical
development are shown in red. Three probability intervals are indicated for precipitation and temperature which are set at 50, 65, and 80%, while the probability
intervals for tropical cyclone development are set at 20, 40, and 60%. 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.
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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.).
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Product Forecast Tools
The outlook maps are currently based on a number of forecast tools, many of which are objective and serve as an objective first guess. The final depiction is an
assessment of these objective forecast tools augmented by the forecaster when based on additional forecast information when appropriate to create the final product.
Forecast tools include MJO composites, empirical and dynamical based MJO, ERW and KW forecasts, and bias-corrected dynamical model guidance from a number of modeling systems.
Tropical cyclone areas are based on MJO composites and statistical and dynamical tropical cyclone forecast guidance products as well as raw model forecast guidance.
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Product Purpose
The product supports the NOAA mission in three primary ways:
- 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
- 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)
- Support various sectors of the U.S. economy (finance, energy, agriculture, water resource management) that have foreign interests.
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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.
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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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Product Resources
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Feedback and Questions
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www.nws.noaa.gov
