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GTH Outlook Map and Data
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Last Updated -
06/17/25
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GTH Outlook Discussion
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Last Updated -
06/17/25
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Valid -
06/25/25 - 07/08/25
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During the past week, the RMM-based MJO index rapidly weakened back into the unit circle following a more amplified signal across the Western Pacific in early June. However, despite the weakening, some coherency remained in its propagation across the Western Hemisphere, and the phase speed has been suggestive of a Convectively Coupled Kelvin Wave (CCKW). Following constructive interference with a westward propagating Equatorial Rossby Wave (ERW) across the Americas, the CCKW weakened as it reached Africa and Eurasia due to destructive interference with the persistent suppressed convective envelope over that region. By week-2, a similar pattern is forecast to take shape as dynamical models indicate increased upper-level divergence developing over the Western Pacific. RMM-based forecasts from the ECMWF and GEFS depict a bimodal distribution of ensemble members, with a clustering of some members within the eastern Indian Ocean and Maritime Continent, and others depicting a stronger signal quickly emerging across the Western Hemisphere indicative of CCKW activity moving across the Pacific.
The interaction between the CCKW and ERW led to increased upper-level divergence aloft across the Americas in the past week. While increased wind shear limited tropical cyclone development across the Atlantic Basin, the favorable upper-level pattern resulted in a continuation of the quick start to the Eastern North Pacific Hurricane Season with 2 additional TC formations during the past week. Tropical Storms Dalila (6/13) and Erick (6/17) both formed to the south of Mexico. While Dalila was short-lived and remained offshore, Erick is forecast to impact the southern Mexico coast at hurricane intensity later this week. Additional CCKW activity during week-2 is likely to continue the fast start to the season, and individual ensemble members from the GEFS and ECMWF depict surface lows spinning up to the south of Mexico and Central America during this timeframe. Therefore, 40-60 percent chances of TC development are posted across the Eastern Pacific during week-2, and 20-40 percent chances continuing into week-3. The GEFS also depicts an enhanced signal for TC activity across the western Caribbean and Gulf of America, but has overdone the potential thus far, precluding any areas for potential TC development from being designated.
Contrary to the Eastern Pacific, the Western North Pacific has seen an extremely slow start to its TC season, although there are some signs activity is beginning to increase. TC Wutip developed across the South China Sea and tracked into the Gulf of Tonkin making 2 landfalls in southeastern China, the second at minimal typhoon intensity. Enhanced convection is forecast to develop across the Western North Pacific by week-2, and combined with the increasing climatology for the basin, this supports a 40-60 percent chance of TC formation from the Philippines to about 140 deg E, with a 20-40 percent chance over the South China Sea. The GEFS and ECMWF indicate a meandering convective envelope by week-3, with a low frequency enhanced convective envelope possibly persisting across the Western Pacific into early July. This justifies a 20-40 percent chance of TC development during week-3, although there is larger uncertainty regarding higher frequency modes of variability which may further enhance or suppress TC development.
Absent clear subseasonal to seasonal forcing modes, the forecasts for above- and below-normal rainfall are based heavily on a consensus of operational dynamical model guidance. Enhanced convection across the Maritime Continent into the Western Pacific during weeks 2 and 3 increases confidence for above-normal rainfall from India eastward across southeastern Asia and into the Western Pacific. Above-normal rainfall is also predicted over the Southern Hemisphere, over Indonesia and Papua New Guinea. In contrast, below-normal rainfall is forecast across the Indian Ocean (week-2), extending into the southwestern Pacific (south of 10 deg N). Below-normal rainfall is also forecast across Interior China extending east to Japan. Above-normal rainfall is predicted across the Eastern Pacific and over parts of central South America during week-2, with below-normal rainfall indicated across the Equatorial Atlantic and eastern Caribbean. By week-3, there is more uncertainty in the overall convective pattern across the Western Hemisphere further reducing forecast confidence.
A heat wave is predicted across the eastern U.S. beginning this weekend into next week supporting elevated probabilities for above-normal temperatures during week-2.
For hazardous weather concerns in your area during the next two weeks, please refer to your local NWS office, the Medium Range Hazard Forecast produced by the Weather Prediction Center (WPC), and the CPC Week-2 Hazards Outlook. Forecasts issued over Africa are made in coordination with the International Desk at CPC.
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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
