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Weeks 2-3 Global Tropics Hazards Outlook (GTH)

For week-1 tropical cylone information and forecasts, please visit the National Hurricane Center and the Joint Typhoon Warning Center. For week-1 precipitation and temperature related products, please visit the Weather Prediction Center or refer to your local NWS office.

GTH Outlook Map and Data
Last Updated - 12/24/24
GIS Ready Formats
Hazard
Tropical Cyclone Formation Probability KMZ KML SHP KMZ KML SHP
Enhanced Precipitation Probability KMZ KML SHP KMZ KML SHP
Suppressed Precipitation Probability KMZ KML SHP KMZ KML SHP
Above Average Temperatures Probability KMZ KML SHP KMZ KML SHP
Below Average Temperatures Probability KMZ KML SHP KMZ KML SHP

Tropical Cyclone Only GTH Map
Precipitation Only GTH Map
Temperature Only GTH Map
Lines Only GTH Map

Latest Product (PDF Format)
Latest Briefing (PDF Format)
GTH Archive
 
GTH Outlook Discussion
Last Updated - 12/24/24
Valid - 01/01/25 - 01/14/25
Recent observations indicate that the intraseasonal Madden-Julian Oscillation (MJO) remains active. Interference from both the low frequency base state and equatorial Rossby wave activity over the Maritime Continent have slowed the eastward propagation of the MJO signal considerably during the past two weeks. In fact, the CPC upper-level velocity potential based index reflects westward movement since mid-December due to the robust Rossby wave projection. Both a potentially developing La Niña event across the central Pacific and an unusually late negatively phased Indian Ocean Dipole (-IOD) event are contributing to a low frequency enhanced convective signal over the Maritime Continent, with a Rossby wave constructively interfering, while the MJO is currently propagating across the Pacific with destructive interference from the base state. Dynamical model MJO index forecasts show a fairly fast transition from the slowly propagating index to a signal over the east-central Pacific. Additional Rossby wave activity over the East Pacific, likely driven by extratropical wavebreaking onto the Equator, will help to break down the enhanced trade wind regime over the East Pacific, allowing the MJO signal to move past the destructive interference and continue propagating towards the Western Hemisphere. Dynamical models vary on the amplitude of the MJO signal over the subsequent two weeks as it crosses the Western Hemisphere and potentially returns to the Indian Ocean, with most ensemble members gradually weakening the signal. Interestingly, the suppressed phase of the MJO seems insufficient to reverse the low-level westerly wind anomalies across the Indian Ocean. Due to this persistent -IOD structure, enhanced convection is favored to persist across portions of the Indian Ocean basin and Maritime Continent despite any MJO influence. MJO activity teleconnects effectively into the northern hemisphere midlatitude pattern during the boreal winter months, with Pacific events tied to pattern changes favoring a transition towards negatively phased NAO (North Atlantic Oscillation) blocking events and increased troughing over the eastern US. A pattern flip reflecting these signals appears likely to occur in early January.

One tropical cyclone developed during the past week, Tropical Storm Pabuk, which formed on 23 December over the South China Sea. Currently downgraded to a tropical depression, Pabuk is forecast to meander close to the southern coast of Vietnam before dissipating under unfavorable atmospheric conditions. During the Week-2 period, despite an unfavorable positioning of the MJO suppressed phase, the low frequency base state may help contribute to tropical cyclone development in a few basins. There is a 40-percent chance of development indicated in the vicinity of the Philippines, either over the northwestern Pacific or the South China Sea. Additionally, there is good model support for a potential tropical cyclone developing over the southern Indian Ocean, though ensemble members are not clustering on a single location. Development is also possible in the vicinity of the Kimberley Coast of Australia, though this region has the lowest confidence. Tropical cyclone development in all of these same regions remains possible during Week-3, with 20-percent chances depicted. As the remnant MJO signal returns to the Indian Ocean, its destructive interference will gradually decrease.

Forecasts for above- and below-average precipitation are based on an anticipated continuation of the -IOD and developing La Niña base state, and an MJO propagation across the Western Hemisphere during Week-2, and possibly the Indian Ocean during Week-3. A skill weighted consensus of dynamical model guidance was also utilized. Above-average temperatures are possible for portions of Brazil and northern Australia during Week-2, with heat persisting across Australia during Week-3. An outbreak of cold air into the central and eastern United States is favored for Week-3. For hazardous weather conditions in your area during the coming two-week period, please refer to your local NWS office, the Medium Range Hazards Forecast produced by the Weather Prediction Center, and the CPC Week-2 Hazards Outlook. Forecasts made over Africa are made in coordination with the International Desk at CPC.




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.

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.


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 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.

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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