The latest observations indicate the MJO weakened over the past week. Although the MJO remains active, it is currently considerably less coherent than during November and early December. Enhanced convection did not shift eastward toward the central Pacific and the low level wind structure is not organized and in any way consistent with MJO activity. The upper-level signal is better defined, although the propagation speed is quite high for canonical MJO activity. Nevertheless, velocity potential anomalies does continue to indicate some MJO activity ongoing with the enhanced phase currently centered across the Atlantic Ocean. The RMM index has lost amplitude. Atmospheric Kelvin (KW) and Equatorial Rossby (ERW) activity is generally minimal. We continue to see above average SST's in the central and eastern Pacific consistent with El Nino like conditions.
Over the past week, suppressed convection was observed across parts of the northern Maritime continent (MC), western Pacific south of the equator east of Papua New Guinea as well as for parts of east Africa. Enhanced rainfall was evident for areas in southern Africa, northern Australia and southwest of Hawaii north of the equator. Tropical cyclone Bakung developed in the southern Indian Ocean over the course of the week, but has since dissipated. No other tropical cyclones developed during the past week.
Looking ahead, the majority of the dynamical model RMM forecasts of the MJO indicate a weak signal during the upcoming week before some potential strengthening of the signal in generally Phase 3 during the Week-2 period. Agreement is good for this evolution, although some models propagate this signal toward the MC more quickly than others thereafter. Longer term forecast models of the RMM index, show a continuation of eastward propagation once again to the western Pacific by early-to-mid January.
The outlook favors continued eastward movement of the upper-level signal consistent with weak MJO activity, although impacts attributed to the MJO are primarily confined to the Week-2 period. The Week-1 outlook is primarily based on GFS, CFS and ECMWF model guidance given the weak signals of most of the modes of subseasonal tropical variability during this upcoming week. The dynamical model precipitation forecasts favor generally small areas of anomalous rainfall during Week-1. Above median precipitation is favored for parts of southern Africa associated with continued frontal activity. Wet conditions are most likely for northeast Brazil and for a narrow area stretching from the Phillippines eastward to Sri Kanka as a series of disturbances with traverse these longitudes. A remaining disturbance in the eastern Indian Ocean has moderate confidence for regeneration into a tropical cyclone during the period as it shifts eastward.
Suppressed rainfall is favored for an area stretching from just north of Australia into the southwest Pacific east and southeast of Papua New Guinea and for areas across eastern Africa. Frontal activity and associated convergence favors above median rainfall for areas in the south Pacific east of the Date Line. There exists a low risk for tropical cyclone development in this active are as well.
For Week-2, the only highlighted area this week is for favored enhanced rainfall in association with an increase in MJO amplitude across the eastern Indian Ocean. Uncertainty in how fast this variability shifts east in the model forecasts and above average SSTs precludes the designation of suppressed convection over the western Pacific, normally observed when the MJO is active in Phase 3.
It is quite difficult to ascertain impacts to the U.S. moving forward until we see if and how organized renewed enhanced convection in the Indian Ocean becomes during Week-2.
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.