The MJO remained incoherent over the past week and this is depicted by both the RMM index and the CPC velocity potential index. The subseasonal coherent tropical varibility continues to be dominated by atmospheric Kelvin wave (KW) activity, the strongest of which currently has its enhanced phase crossing the Americas with the suppressed phase located over the Pacific basin. The pattern overall remains highly influenced by the low frequency El Nino state.
Enhanced convection was observed during the past week across most of the Pacific basin primarily along and north of the equator with suppressed convection evident across the Maritime continent (MC). Moisture from this enhanced Pacific convection interacted with the extratropical circulation in the northern hemisphere and resulted in enhanced precipitation across the southern continental U.S. resulting in flooding rains in some areas. Low-level westerly wind anomalies over the western equatorial Pacific remain strong.
Tropical cyclone Dolphin severely impacted Guam and reached super typhoon status during the past week and is currently forecast to recurve into the westerlies over the next day or two and its remnants may impact Alaska during the upcoming week.
Dynamical model forecasts of the RMM index indicate a continued weak MJO signal over the next two weeks as does most statistical forecast tools. The official outlook is based on a combination of El Nino conditions, atmospheric KW activity during Week-1 and model guidance from the GFS, CFS and ECMWF.
Early in the period, strong southerly flow is likely to produce above median precipitation across northern Mexico into the continental U.S. Also during Week-1, the robust atmospheric KW crossing the Americas is likely to enhance convection over portions of west Africa. Model guidance also provides supportive evidence for this area as well. The suppressed phase of this KW may temper convection across some portions of the Pacific basin. Enhanced convection is highlighted, therefore, where model depicts the strongest signal amongst modeling systems. Drier than average conditions are favored for the Caribbean consistent with El Nino and model guidance from the ECMWF and CFS. The Meiyu front is expected to remain enhanced during both Week-1 and Week-2. Consistent with the El Nino base state and model guidance, suppressed convection is forecast for the MC into the far western Pacific for both Week-1 and Week-2. Suppressed convection is forecast to continue for Week-2 over the Caribbean and Americas, consistent with El Nino and model guidance.
Tropical cyclone activity is likely to be limited overall globally during the period but there is some potentiual for tropical development in the eastern Pacific basin late Week-1 into early Week-2 so a moderate confidence area is highlighted. GFS and ECMWF indicate this potential and this is also consistent with the timing of an additional KW in the area.
Depicted area of suppressed rainfall over Africa are produced in collaboration with CPC’s 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.