Consistent with the dynamical model forecasts from last week, the CPC velocity potential-based and RMM-based MJO indices both depict an enhanced MJO signal that has returned to the Indian Ocean, similar to the beginning of March. The period of this intraseasonal signal is around 20 days, which is considerably faster than a canonical MJO and more in line with values expected from Kelvin wave activity. Additionally, while the signal is well represented in the wind field, particularly in the upper troposphere, the convective pattern across the global tropics, observed via OLR anomalies, is not consistent with robust MJO activity. The low frequency base state favoring enhanced (suppressed) convection over the western Indian Ocean and Date Line (Maritime Continent) continues to be the primary driver of large-scale convective anomalies, with the fast intraseasonal signal failing to couple substantially with the convection. There is some evidence, however, that the suppressed phase of the intraseasonal signal has weakened the persistent enhanced signal near the Date Line. Dynamical model MJO index forecasts continue to show a fast eastward propagation of the intraseasonal envelope, with the GEFS ensemble mean maintaining some amplitude across the West Pacific during Week-1 and the Western Hemisphere by Week-2. The ECMWF weakens the signal considerably over the Pacific, as the forecast convective anomalies remain weak and reflect the base state rather than MJO activity.
No new tropical cyclones developed during the past week. During Week-1, there is some dynamical model support for a potential low-latitude formation in the vicinity of the Philippines, either just west of Mindanao early in the period, or the South China Sea later in the period. Additionally, an area of enhanced convection currently over the Gulf of Carpentaria has a moderate potential for development as it moves slowly westward towards the Kimberley Coast late in Week-1 or during Week-2. Finally, several ensemble members of the GEFS depict a formation further west over the southwestern Indian Ocean during Week-1, but confidence is too low to include a hazard on the outlook.
Given the lack of substantial convective coupling to the intraseasonal signal, the precipitation forecast is based largely on dynamical model consensus, and is more reflective of the ongoing low-frequency state. During Week-1, enhanced convection is favored across parts of eastern Africa, the southern Indian Ocean, and extending from the eastern Maritime Continent across the North Pacific ITCZ region. Additionally, enhanced storminess is favored for parts of the northern Mediterranean region and Middle East, while widespread heavy precipitation is forecast to extend from eastern China to southern and central Japan. Precipitation anomalies across South America are based primarily on the ECMWF ensemble mean. During Week-2, the low-frequency base state and dynamical model consensus favor enhanced (suppressed) convection over the southern Indian Ocean and the central Pacific (Maritime Continent), while the fast moving intraseasonal signal may help bring enhanced rainfall to the equatorial Atlantic.
Forecasts over Africa are made in consultation with CPCs international desk in addition to dynamical model consensus, and can represent local-scale conditions in addition to global-scale variability.
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.
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.
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.