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GTH Outlook Map and Data
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Last Updated -
04/01/25
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GTH Outlook Discussion
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Last Updated -
04/01/25
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Valid -
04/09/25 - 04/22/25
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Based on RMM index observations, the Madden-Julian Oscillation (MJO) rapidly propagated eastward from the western Indian Ocean into the western Pacific Ocean in a little over a week from 3/15-3/24. Since then, the signal retrograded westward towards the Maritime Continent before retreating back inside the unit circle. The GEFS and ECMWF agree on a weak MJO signal switching back to an eastward propagation into the Eastern Pacific and Atlantic Oceans during Week-1 (4/2-4/8). However, by Week-2 (4/9-4/15), the signal tends to revert back to a westward propagation with the signal remaining in the unit circle and moving back into the Western Pacific. The GEFS shows a strengthening MJO signal over the Pacific Ocean during Week-3 (4/16-4/22), while the ECMWF continues a stagnant signal in the unit circle over the Western Pacific. The model forecasts for 200-mb velocity potential (VP) anomalies show that the strong divergence aloft over the Maritime Continent weakens during Week-1 and gives way to a very chaotic pattern, consistent with the RMM index forecasts. The GEFS begins to reorganize in Week-2, holding on to this enhanced convection over the Maritime Continent as it constructively interferes with the strong, low frequency signal collocated at 130E. A Wave-1 pattern fully emerges in Week-3 with the convective envelope propagating eastward into the Pacific Ocean. The ECMWF solution shows a different story with an incoherent pattern remaining in Week-2 and Week-3, and a low-frequency signal located at 80W versus the GEFS signal near 130E. Although no Wave-1 pattern exists, the MJO signal remains through the filtering and moves across the Pacific, causing some enhanced convection along the eastern Pacific Ocean in Week-3 as it interacts with the low-frequency signal. La Nina continues to show signs of weakening as warm temperature anomalies increase in the eastern Pacific and approach lower ocean depths. This may be causing the dueling low-frequency signals between the models.
After becoming a Tropical Cyclone (TC) on 3/24, TC Courtney (27S) continued moving westward into the open ocean of the South Indian basin before turning southward. The Joint Typhon Warning Center (JTWC) issued its final warning on the system on 4/1. TC Dianne (28S) formed off the Kimberley Coast of Australia on 3/28 after being tracked by the JTWC as a depression since 3/25. It quickly made landfall a day later in Australia, southeast of Kooland Island. During the Week-1 period, the ocean basins remain fairly quiet with little chance of tropical cyclogenesis.
Because of the weak and conflicting MJO pattern, TC forecasts rely heavily on model guidance. During Week-2, the ECMWF and GEFS both show an increased chance of TC development along Northern Australia between 10-20S from northwest of the Kimberley coast eastward into the South Pacific Ocean. Low-level westerly anomalies remain fairly strong in this region in both the CFS and ECMWF, signaling a favorable region for TC development. By Week-3, the signal has shifted further eastward into the South Pacific Ocean. This is consistent with the stronger MJO signal in the GEFS over northern Australia during both Week-2 and Week-3. Climatologically, mid-April is the quietest period globally for tropical cyclogenesis. Between this and the conflicting MJO signal, only a 20-40% chance of development is warranted for both time periods. There is a weak indication of formation east of the Philippines in Week-2; however, probabilities remain below 20%.
Like the TC forecasts, forecasts for enhanced and suppressed precipitation are based heavily on a skill weighted consolidation of the GEFS, CFSv2, and ECMWF ensemble forecast systems, with considerations of historical MJO composites for phases 5-7 during Mar-May and the lingering La Nina influence. The dry signal associated with La Nina remains in the Pacific but only north of the equator. A wetter signal that has appeared over the past month continues south of the equator and into the South Pacific. The increased chance for above-average precipitation north of Australia persists into the Week 2-3 time period. Chances for above-average temperatures remain in southeast Brazil near the Atlantic coast.
For hazardous weather conditions in your area during the next two weeks, please refer to your local NWS office, the Medium Range Hazards Forecast from 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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