The MJO signal remained weak during the past week. The dynamical model MJO forecasts depict a continued weak signal during Week-1, but the ECMWF model indicates an increase in the amplitude of the RMM index over the Indian Ocean during Week-2. Multiple atmospheric Kelvin Waves and an equatorial Rossby Wave are evident in the observed Outgoing Longwave Radiation (OLR) anomaly field. Although El Nino is waning, its atmospheric effects continue with areas of enhanced (suppressed) convection noted across parts of the central Pacific (Maritime Continent).
The precipitation outlook during Week-1 is based largely on CFS and ECMWF model guidance, along with some influence from an equatorial Rossby Wave, atmospheric Kelvin Waves, and the waning El Nino. Above-median rainfall is favored across parts of the central Pacific, Indian Ocean, Kimberley Coast of Australia, and the Horn of Africa. The highest confidence for above-median rainfall during Week-1 exists from Hispaniola and Puerto Rico north to Bermuda, where an amplifying mid-latitude trough is likely to interact with tropical moisture. A heat wave affected Southeast Asia during April and above-normal temperatures are likely to persist through at least Week-1 across Cambodia, Laos, and Thailand.
During Week-2, the CFS and ECMWF models agree that above-median rainfall will continue across the Horn of Africa and western Indian Ocean. Above-median rainfall forecast across far southern India, Sri Lanka, and parts of the central Indian Ocean is related to the potential for a developing MJO by mid-May. Model guidance and the waning El Nino support above-median rainfall across parts of the south-central Pacific. Confidence is too low to depict any favored below-median rainfall areas on this outlook map.
Tropical cyclone development is unlikely across the global tropics during the next two weeks. This inactive period for tropical cyclone genesis is typical for early May.
Forecast over Africa are made in consultation with CPC's international desk, and can represent local-scale conditions in addition to global-scale variability.
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.