The RMM-based MJO index indicates a weak signal during the past week, while the CPC velocity potential based index indicates little coherent signal, as well. The pattern of convection continues to be largely dominated by the high-amplitude low-frequency state, though robust atmospheric Kelvin Wave activity is also contributing. This is most evident over parts of the Maritime Continent where enhanced convection is currently observed, which is at odds with the ongoing ENSO state.
Dynamical model outputs generally indicate a weak MJO signal during the next two weeks, although the GEFS forecast has a very weak signal over the Western Hemisphere during Week-2. This could be a reflection of the evolution of the background state, or due to continuing Kelvin Wave activity. In either case, the MJO is not expected to contribute to any significant portion of tropical convective variability. Statistical tools indicate little coherent MJO signal as well. Therefore, the forecast is based on the ENSO state and dynamical guidance from the CFS and ECMWF coupled systems.
No tropical cyclones developed during the past week. During the next 7 days, tropical cyclone formation odds are enhanced near the Kimberley Coast of Australia. There is a low chance of a weak tropical cyclone forming near Madagascar during the next several days, though the probability is too low to warrant a map depiction. During Week-2, the only region that can be delineated on the map is a fairly large region in the Northwest Pacific, where overall conditions seem somewhat favorable. Over the Indian Ocean near Sri Lanka, there is a low risk of formation associated with a forecast area of enhanced convection. The latest 06Z run of the GEFS indicates about a 10 to 15 percent chance of formation over the eastern Pacific basin, and the coupled CFS system suggests the first system in that basin could form as early as Week-3. This will continue to be monitored closely.
During Week-1, convection is likely to be enhanced over much of the Pacific cold tongue extending to near the Date Line due to the ENSO state. This convection could bring heavy rains all the way to the South American coast. Suppressed convection is more likely over parts of Southeast Asia from the Bay of Bengal to the South China Sea, as well as parts of the Maritime Continent. In spite of the robust low-frequency state, confidence is lower here due to the enhanced phase of a Kelvin wave impacting this region early in the period. Dry conditions are favored over northeast South America and parts of the Caribbean Sea, with above-average rainfall favored farther south over parts of South America.
For Week-2, convection is forecast to be above average from west of the Date Line all the way to the South American coast. Both the CFS and ECMWF are in agreement on this point. In the wake of the enhanced Kelvin wave convection over the Maritime Continent early in Week-1, suppressed rainfall is highly likely over most of the Maritime Continent and Southeast Asia. Models are in good agreement indicating enhanced rainfall over the Gulf of Mexico and adjacent coastal regions. The low-frequency state is expected to continue to favor the pattern indicated over South America, namely, suppressed rainfall across the northern part of the continent and enhanced rainfall to the south.
Depicted areas of enhanced or suppressed rainfall over Africa are produced in collaboration with CPC’s Africa Desk.
Product Release Information
The Global Tropics Hazards and Benefits Outlook is released once per week every Tuesday at 1530 UTC (1630 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.
The Global Tropics Hazards and Benefits Outlook is a forecast for areas with elevated odds for above- or below-median rainfall and regions where tropical cyclogenesis is favorable or unfavorable for the upcoming Week-1 and Week-2 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 yellow respectively. Favored areas for tropical development are shown in red. Two measures of confidence are indicated, high (solid) and moderate (hatched) and are currently subjective in nature and not based on an objective system. Work towards a probabilistic format of the product and so an objective measure of confidence is ongoing. 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 created subjectively based on a number of forecast tools, many of which are objective. The final depiction is an assessment of these forecast tools based on a number of factors to create the final product. Work is ongoing to create an objective consolidation of some of the available forecast tools to serve as a first guess for the forecaster. Forecast tools include MJO composites, empirical and dynamical based MJO, ERW and KW forecasts, and raw dynamical model guidance from a number of modeling systems. Tropical cyclone areas are based on MJO composites and statistical and dynamical tropical cyclone forecasts as well as raw model forecast guidance.
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.
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.