The MJO remains generally weak and unorganized and similar to the last several weeks, other subseasonal, coherent tropical variability are dominating the pattern of anomalous tropical convection. Along with the ongoing low frequency background conditions, two important subseasonal features are playing strong roles, namely a robust westward moving equatorial Rossby wave (ERW) located across the western Pacific and a strong, somewhat slow moving eastward propagating atmospheric Kelvin wave (KW) in the central Pacific. Both these features are anticipated to produce impacts in the Tropics in the upcoming outlook period.
During the past week, enhanced convection was observed for an area stretching from India across Southeast Asia into the western Pacific to near the Date Line. Suppressed convection was evident along the equatorial Indian Ocean and parts of Central America, the Caribbean and northern South America. Typhoon Matmo developed east of the Philippines during the past week and is expected to make landfall in Taiwan just prior to the start of this forecast period. Also, tropical cyclone Wali developed in the central Pacific and a small scale tropical depression developed in the central Atlantic in recent days.
The majority of dynamical model forecasts of the RMM index continue to indicate weak or incoherent MJO activity during the next two weeks. These include the GFS, Canadian, JMA and Taiwan Central Weather Bureau models. The ECMWF and CFS forecasts, however, indicate a more amplified, eastward propagating signal over the next weeks. The propagation speed is somewhat fast and of generally only weak to moderate amplitude and may be primarily in response to the somewhat slowly evolving KW mentioned above. The MJO is unlikely to play a major role in anomalous tropical convection and highlighted impacts are principally based on the KW and ERW evolution, the tilt toward a warm ENSO base state and model guidance.
Typhoon Matmo is expected to produce areas of heavy rainfall along its track as it makes a second landfall in eastern China early in the period. Moisture from this system is favored to produce above average rainfall across South Korea during the period as well. The evolution of the ERW in the western Pacific is consistent with model guidance for wet conditions in much of the western Pacific during the next two weeks along with the threat for additional tropical cyclogenesis east of the Philippines during Week-1 and later during Week-2 centered at about 20 N, 135E. Considerable drying associated with the suppressed phase of the KW in Week-1 and any potential evolving weak MJO signal favors below median precipitation along the equator from the eastern Indian Ocean across the Maritime continent over the course of the outlook. This is supported by model guidance.
KW activity likely to continue crossing the Pacific basin elevates the threat for tropical cyclogenesis in both the central and eastern Pacific basins and this is supported by model guidance. The east Pacific ITCZ continues to be shifted south and west compared to climatology and so the threat for tropical development continues in Week-2, but somewhat displaced from the Mexico coast. Suppressed rainfall is favored to continue across significant areas of Central America, Mexico and the Caribbean.
Strong frontal activity as indicated by model guidance is highlighted during Week-1 in proximity to southern Brazil. Forecasts of enhanced or suppressed convection across some parts of Africa are based on regional scale anomaly features and were produced based on collaboration with the CPC 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.