The MJO remained active during the past week though several observational indicators depict a notably less coherent and considerably weaker signature than previous weeks, a trend that began a couple of weeks ago. The RMM index and the CPC velocity potential MJO index both show weak projections on MJO activity. The former showing little eastward propagation over the last 10 days centered across the central Pacific (i.e., Phase 7). Viewing other observations such as time longitude diagrams of raw anomalous 200-hPa velocity potential and equatorial OLR, any enhanced convective phase of the MJO is now most likely located across the Americas.
Further complicating the pattern of anomalous tropical convection continues to be a robust equatorial Rossby wave (ERW) interfering with the MJO signal across the Indian Ocean (IO) and Maritime continent (MC) regions. This further contributes to the less clear MJO signature and high uncertainty beyond Week-1 for main centers of action for anomalous tropical convection.
Nearly all the dynamical model forecasts of the MJO index show continued weakening of the MJO signal in Week-1 so there is good agreement overall over the next several days. There is high spread, however, entering Week-2 with the NCEP, JMA, Taiwan Central Weather Bureau and to a lesser extent the UK Met Office indicating a stronger projection of the RMM index once again over the western Pacific, while the ECMWF solutions showing a continued incoherent MJO signal.
For Week-1, the constructive interference of the weakening suppressed convective phase of the MJO and the suppressed phase of the ERW favors reasonable confidence for below median rainfall for areas in the eastern Indian Ocean, northern Australia, parts of the southern and western MC and a region near the Philippines. Areas along the equator are not highlighted due to more active precipitation expected in these areas. Residual MJO influence, above average SSTs and model guidance support a continuation of a very active southwest Pacific Island region with favored tropical cyclone development in two separate areas. General anomalous convergence indicated by model guidance, tropical cyclone 8S and potential further tropical cyclone development prior to or very early on in ther period favors above-median rainfall in the south-central IO. Despite residual MJO phase, strong model support favors below-median rainfall across interior Brazil during Week-1. Tropical moisture from a residual MJO influence along with a shortwave trough favors a plume of moisture into the northwest Mexico and parts of the Southwest CONUS.
At the current time, it is unclear, at what strength, if any, the MJO will emerge after interference with the strong active ERW previously described and also to what degree and impact the more persistent enhanced convection in the western Pacific will have moving forward. Uncertainty in the anomalous tropical convective pattern is quite high in Week-2 so highlighted areas of anomalous precipitation are quite modest at best. A high confidence area of below median rainfall is indicated for areas across northern Australia and with a slightly lower confidence for persistence of above-median rainfall and favorable conditions for tropical cyclone development for portions of the western Pacific in Week-2. Good model agreement between the CFS and ECMWF support a dipole of drier (wetter) than average conditions for northern South America (southeast Brazil).
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.