The RMM index reveals a weak MJO signal over the past several days, while the CPC velocity potential index shows rapid eastward propagation of a weaker, though still coherent signal. In the context of the latter, the enhanced phase is now over the central Pacific, while the RMM index is being heavily influenced by convective activity over the Indian Ocean. It is important to keep in mind that the RMM index explicitly removes the previous 120-day mean, so it is likely that the CPC index is more heavily influenced by the current ENSO state. Taken together, the indices suggest that the current situation is best summarized as being influenced by multiple modes of subseasonal variability, including weak MJO activity, as well as a robust low-frequency state given the time of year.
Dynamical model MJO index forecasts generally indicate little in the way of coherent MJO activity. Statistical models favor slow eastward propagation of a stronger signal over the next two weeks, but these solutions are not strongly considered here due to the ongoing El Niño. Based on the dynamical guidance, the MJO is forecast to play a lesser role over the next two weeks as the ENSO base state remains more important, especially over the Maritime Continent and Pacific Ocean.
Tropical Storm Solo formed over the eastern part of the Coral Sea during the past week, and lasted only a couple of days. The Joint Typhoon Warning Center is currently monitoring a tropical disturbance over the southeastern Indian Ocean; however, the odds of tropical cyclone (TC) formation are low, and so a shape is not depicted for this region. Enhanced rainfall, however, is more likely in association with this feature over the next several days. There are two other areas, one north of Australia and the other over the northwestern Pacific, where TC formation is possible in late Week-1 or early Week-2. These areas are strongly indicated as favorable by the GEFS, and seem reasonably consistent with the forecast convective pattern over the next two weeks.
Regions depicted favoring enhanced or suppressed rainfall over the next two weeks are based mostly on the consensus between the CFS and ECMWF coupled model systems and the ENSO state, with some weak MJO activity considered. In general, enhanced convection is favored over the central and eastern Pacific, while suppressed convection is more likely over parts of the Maritime Continent. Enhanced convection is forecast during Week-1 over parts of the eastern Indian Ocean away from the equator, where the model guidance is supportive and ongoing activity is currently observed. Over South America, drier-than-average conditions are favored for the northeastern part of the continent, while the enhanced phase of the remnant MJO is conducive for enhanced rainfall farther south. This pattern is generally forecast to remain in place during Week-2 according to the dynamical models.
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.