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GTH Outlook Map and Data
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Last Updated -
06/03/25
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GTH Outlook Discussion
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Last Updated -
06/03/25
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Valid -
06/11/25 - 06/24/25
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Latest observations continue to point to disorganized MJO activity, with the RMM signal still meandering in and out of the unit circle over phases 4 and 5 during the past week. The recent tendency towards a positive RMM1 during the past few weeks is likely tied to the strong lower-level westerly anomalies mainly north of the equator over the Indian Ocean. This has contributed to a robust onset of the Indian monsoon, with the rest of the tropics continuing to be dominated by higher frequency modes and a low frequency convective response along/near 120E since late March. Consistent with previous dynamical model guidance, RMM forecasts continue to advertise a reorganizing MJO in June with the ECMWF remaining the most bullish with this realization. Notably, its latest RMM solutions depict a canonical eastward propagation over the Western Pacific and Western Hemisphere at a higher amplitude, with a tighter clustering of ensemble members around the ensemble mean in RMM space during the next two weeks. Moreover, there has been good consistency in the upper-level velocity potential forecasts favoring more of a wave-1 pattern taking shape with enhanced divergence aloft returning to the Eastern Hemisphere. By comparison, renewed MJO activity is also supported by the GEFS and CFSv2, but both fail to maintain propagation of the MJO, while favoring more of a low frequency response over the Maritime Continent resulting in a multiple upper-level divergence envelopes later in June. Given the continued discrepancies among the dynamical models, there remains a fair degree of uncertainty, especially at the longer leads, though there is overall better support for a more coherent MJO playing a role in the tropics in the updated outlook.
One Tropical Cyclone (TC) developed in the past seven days. As the first TC of the season for the eastern Pacific, Alvin formed on 5/29 to the south of Mexico near 105W, and strengthened to Tropical Storm intensity before dissipating near the tip of Baja California on 5/31. While Alvin was not a particularly impactful system near Mexico, its proximity to the mouth of the Gulf of California looks to have triggered an early season gulf surge event, ushering in tropical moisture into the southwestern CONUS, and led to locally heavy rainfall and flooding concerns over the Desert Southwest earlier this week. Combined with an approaching mid-level trough, the added mid-tropospheric moisture is expected to bring enhanced, and possibly excessive precipitation to parts of the central and western CONUS this week. Potentially heavy precipitation is also possible this week over the coastal Southeast and Mid-Atlantic associated with an offshore low forecast, where the National Hurricane Center (NHC) gives 10% chances of this low acquiring tropical characteristics later this week. The NHC is also monitoring another area to the south of Mexico for TC development with 70% chances for genesis during week-1.
Following the potential TC development in the eastern Pacific during week-1, 40% chances are posted to the south of Mexico for additional development in the basin for week-2. Accompanied by renewed MJO activity favored to propagate into the Western Hemisphere, objective wave filtering of upper-level velocity potential forecasts also highlight the intersection of equatorial Kelvin and Rossby wave activity early in week-2. The superposition of these tropical modes is likely to produce strongly enhanced divergence aloft between 120W and 80W, conducive for genesis. However, inhibiting factors in the model guidance include strong subtropical ridging and high shearing over parts of the Gulf of America and the western Caribbean during week-2, which looks to suppress this potential. Therefore, a broader area of 20% chances is posted from approximately 110W and extending eastward to cover the Bay of Campeche and the Gulf of Honduras. This posted area falls in-line with the climatological increase in TC activity for mid-June, and also closely resembles the week-3 outlook issued last week. Although there is higher uncertainty with the strength and phasing of MJO later in June, 20% chances for TC development are again posted to the south of Mexico and Bay of Campeche for week-3 based on where there is greatest agreement in extended range probabilistic tools.
In the Eastern Hemisphere, medium range ECMWF probabilistic guidance shows increases in TC genesis signals centered over the Bay of Bengal and over the northern South China Sea. In consideration of the TC climatology tapering off by mid-June in the northern Indian Ocean due to monsoonal shearing, and the suppressed phase favored to overspread the basin, no TC shapes are posted. However, 20% chances are issued in the South China Sea where the environment looks to be more favorable for development. Should the MJO remain coherent during week-3, this would favor below-normal odds for TC formation in the western Pacific. Given stronger support for suppressed precipitation in the basin, with modest signals in the probabilistic tools, no shapes are posted for the western Pacific for week-3.
Forecasts for enhanced and suppressed precipitation are based on an historical skill weighted blend of GEFS, ECMWF, and CFSv2 dynamical model ensemble guidance, anticipated TC tracks, with some consideration of residual La Nina background conditions and phase 8 and 1 MJO composites for May-Jul. Due to antecedent wet conditions associated with robust onset of the Indian monsoon (where several areas in India and Southeast Asia have registered 2 to 6 times their normal rainfall accumulation over the past 30 days based on gauge measurements), any near to above-normal precipitation may trigger localized flooding and other adverse ground impacts during the outlook period. Above normal temperatures with the potential for extreme heat conditions are posted over parts of Africa, South America, and parts of the western and eastern CONUS for 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
