The MJO weakened slightly during the past few days, especially according to the RMM-based index. The CPC velocity potential index indicates a stagnant signal, with enhanced convection supported over the Maritime Continent. Forecasts range from a spatially stagnant signal to slow eastward propagation. The update reflects a continuation of enhanced convective activity over the Maritime Continent and western Pacific.
The National Hurricane Center indicates a 90 percent chance of tropical cyclone formation over the eastern Pacific during the next 5 days. Tropical cyclone formation odds are slightly enhanced near the Lesser Antilles for the next 5 days, then over the Caribbean and Great Antilles into Week-2. Tropical storm Megi developed just west of Saipan, and is forecast to move toward Taiwan. Tropical cyclone formation odds are enhanced for the western North Pacific for the extent of the outlook.
Areas of above/below average rains have been adjusted, in accordance with predicted tropical cyclone activity and model guidance. Heavy rains are likely over northern Mexico and southern Texas during the early portion of next week. Any disturbance, whether a declared as tropical cyclone or not, will likely bring heavy rains to the Caribbean and surrounding islands.
--------------------- Previous discussion follows -------------------------------
The MJO strengthened during the past 7-days, with the RMM-based index and the CPC velocity potential based anomalies indicating conditions associated with enhanced convection over the Maritime Continent. Spatially, velocity potential anomalies indicate support for convection from the Indian Ocean to the Central Pacific, with subsident conditions from the Americas to Africa, and that pattern is slowly sliding eastward. An equatorial Rossby wave (ERW) and a Kelvin wave are also impacting the circulation near the Date Line. Going forward in time, most models predict a slow eastward propagation of the signal, with convection remaining over the Maritime Continent and western Pacific for the next 10 days. GFS and Environment Canada model based solutions have slower propagation, likely due to more emphasis on the ERW.
During the past week, Hurricane Paine developed over the eastern Pacific and both Tropical Storm Karl and Tropical Storm Lisa developed over the Atlantic, continuing the active period for tropical cyclone activity. Typhoon Malakas continued to spin over the West Pacific, directly impacting Japan. During the next two weeks tropical cyclone formation is likely over the western Pacific, from about 130E to 165E along 15N. During the next 5 days, the National Hurricane Center indicated a 50% chance of tropical cyclone formation over the East Pacific. During Week-2, the West Pacific is likely to remain active from near Taiwan out to 165E, while some activity is also indicated over the Atlantic, likely tied to Kelvin wave activity across this region.
During Week-1, moderate likelihood areas of above average rainfall are forecast over India, associated with a monsoon depression that developed over the country last week, which is forecast to slide westward in time. Above average rainfall is also likely over the Maritime Continent due to the MJO/ERW interactions there. Tropical cyclones are likely to bring heavy rains to Japan, northwest Mexico, and portions of the Atlantic Ocean and eastern Pacific. Below average rains are likely over the western Indian Ocean, due to MJO and ERW influences, and over central and eastern Pacific. Confidence over the central and eastern Pacific are lower due to the potential influence of a Kelvin wave to move through that region and disrupt the subsidence from the MJO.
For Week-2, below average rains are likely over the eastern Indian Ocean and western Maritime Continent, while above average rains are likely to stretch eastward to Papua New Guinea and portions of the western Pacific. Below average rains over the central Pacific are likely where SSTs are below average and areas east of the projected influence of the MJO.
Forecasts over Africa are generally made in consultation with CPCs international desk, and can represent local-scale conditions in addition to global-scale variability.
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Product Release Information
The full Global Tropics Hazards and Benefits Outlook (GTH) is released once per week every Tuesday at 1730 UTC (1830 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 and soon will be recorded.
CPC also issues an operational update of this product every Friday by 1730 UTC to further support the NWS regions. The update only spans the release period from June 1 through November 30 and a region from 120E to the Prime Meridian in longitude and from the equator to 40N in latitude. The update does not extend the time horizon of the product, but rather applies for the remaining 4 days of the previous Week-1 time period and Days 5-11 from the previous Week-2 period. This page will depict both the original and updated outlook maps as well short text outlining the forecast rationale for any changes.
Product Description
The Global Tropics Hazards and Benefits Outlook is a forecast for areas with elevated odds for above- or below-median rainfall, above- or below-normal temperatures and regions where tropical cyclogenesis is favored 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. Above(below) normal temperature forecast areas are depicted in orange and below 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.
Product Purpose
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.
Product Partners
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.
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