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Weeks 2-3 Global Tropics Hazards Outlook (GTH)
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Outlook Map and Data
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Last Updated -
03/28/23
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Outlook Discussion
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Last Updated -
03/28/23
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Valid -
04/05/23 - 04/18/23
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Following a robust Madden Julian Oscillation (MJO) across the Western Hemisphere earlier in March, the intraseasonal signal has since weakened as it moved over the Indian Ocean during the past week. The GEFS and ECMWF dynamical model ensembles are in good agreement regarding a weakened MJO signal for the next week followed by renewed strengthening across the Maritime Continent and Western Pacific in early April. This could lead to an extratropical response typical of La Nina, possibly leading to above (below) normal temperatures over the eastern (western) contiguous U.S. during April.
The global tropics have remained quiet throughout much of March due to a highly suppressed convective envelope across the Indian and Pacific Oceans, with the only tropical cyclone (TC) formation being short-lived and weak Tropical Depression 9 over the Southern Indian Ocean on March 25. However, there are signs of additional TC activity over the Southern Indian Ocean during the next week, with the Joint Typhoon Warning Center monitoring two disturbances for potential development (96S and 97S) over the basin. By week-2, TC activity is forecast to shift closer to northwestern Australia as the MJO strengthens over the Maritime Continent and Western Pacific, with the suppressed phase moving back over the Indian Ocean. The GEFS and ECMWF ensembles both depict a TC possibly developing late in week-1 or early in week-2 and moving toward the Kimberley Coast of Australia. Therefore, moderate chances (40%) of TC formation is highlighted to the northwest of Australia through the Timor Sea. Upper-level conditions are favored to support continued increased chances of TC development through week-2, should the initial disturbance develop prior to the start of the period. Although enhanced convection is forecast over the Western North Pacific during week-2, the TC climatology for the period is still fairly low, precluding a related risk area for the region. However, increasing climatology combined with the MJO may lead to increased chances of TC development across the region by mid-April.
Forecasts for above- and below-normal rainfall are based on a skill weighted blend of extended range dynamical models and historical MJO composites. Notably, above-normal rainfall is forecast across portions of the east-central contiguous U.S. during week-2 where frontal activity may trigger episodes of heavy, convective rainfall. Above-normal rainfall is also favored over the eastern equatorial Pacific through week-3, and this may adversely impact parts of Ecuador and northern Peru, which have experienced floods and landslides due to heavy rainfall received during March. The MJO signal shifting into the Western Pacific during weeks 2 and 3 supports increased chances of above-normal rainfall across northern Australia regardless of TC formation.
For hazardous weather concerns 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 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 webinar) open to all interested parties in which the latest conditions in the Tropics
and the just released outlook and associated impacts are discussed. There is an opportunity to ask
questions after the briefing and the briefings are available at the Live Briefing
Archive.
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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
