Over the past seven days the Madden-Julian Oscillation (MJO) remained over the Maritime Continent. The CPC velocity potential-based index depicts a fairly robust event, which is also supported by the emergence of negative outgoing longwave radiation anomalies over the Maritime Continent in opposition to the low-frequency signal we would expect given the ongoing El Nino. Counterintuitively, the RMM index shows the MJO weakening substantially, with the signal near-zero in the latest observations. The reasons for the failure of the RMM index to track the MJO appear twofold. First, a Kelvin wave is currently across the Western Hemisphere and is serving to divide the signal between two competing centers of action that are roughly 180 degrees out of phase. Second, the increasing atmospheric response to the anomalously warm sea-surface temperatures near the Date Line with the ongoing El Nino is causing the long-term mean signal to favor Phases 7/8 (shifting away from Phases 3/4), to the point that it has become difficult for the intraseasonal signal to manifest itself. Despite this, there appears to be little reason to doubt the MJO's progression to the West Pacific some point next week given the MJO's resiliency as it passes through the low frequency suppressed convective signal over the Maritime Continent. Phase 5 conditions are largely favored in Week-1, with the MJO entering the West Pacific (Phase 6) during late in Week-1 or early in Week-2. The Phase 6 conditions could be interesting given the superposition of the enhanced phase of the MJO with the El Nino convection, and potentially supporting a robust extension of the subtropical jet across the Pacific.
Two tropical cyclones (TCs) formed over the past week in the Southern Hemisphere. The first of these was TC Savannah, which developed near 12S/96E on the 14th. Savannah reached peak intensity on the 17th, with 100 knot winds, but the system has remained well-removed from any landmasses during its time as a TC. TC Trevor formed in the Coral Sea near 13S/146E on the 17th and quickly intensified to possess 100 knot winds by the 19th. Trevor is forecast to track west across Queensland and enter the Gulf of Carpentaria early in the forecast period, with the system anticipated to reintensify before a second landfall in the Northern Territory around the 23rd. Elsewhere, the Joint Typhoon Warning Center (JTWC) gives a high chance of development to a disturbance near 14S/121E (as of 3Z on 19 March), with model guidance suggesting the system will parallel the Kimberly Coast before a possible landfall near Exmouth late in Week-1. JTWC also is monitoring a disturbance near 13S/63E (as of 3Z on 19 March), with a low potential for undergoing tropical cyclogenesis in the next 24 hours. Conditions are more favorable for the system to form later during Week-1, with high confidence of this occurring. Lastly, a moderate confidence for TC formation exists in Week-1 tied to a Rossby wave forecast to track between 145-130E and 5-10N. Confidence is insufficient to forecast any TC development during Week-2 at this time.
During Week-1, confidence for above-median precipitation is high along the anticipated tracks of each of the four ongoing or forecast TCs in the Southern Hemisphere, in addition to the current El Nino footprint in the Tropical Pacific. Confidence is lower for below-median precipitation potential across the southeastern Indian Ocean and over the Maritime Continent, tied to destructive interference of El Nino and the MJO. Remaining above- and below-median precipitation areas with moderate confidence across South America and the Atlantic are a result of GFS and ECMWF model consensus.
Confidence on the whole during Week-2 is substantially lower for most areas, given the uncertainty of how quickly the MJO will make it into the Pacific and lack of substantive tropical forcing outside of El Nino. High confidence for above-median precipitation exists across a similar portion of the Tropical Pacific in Week-2 in association with the low frequency state. There is some potential for the subtropical jet to be extended across the Pacific, leading to moderate confidence for above-median precipitation across parts of California and the Southwest. Moderate confidence for below-median precipitation exists across the southeastern Indian Ocean in Week-2 in association with the suppressed phase of the MJO anticipated to be across the region. Remaining areas of moderate confidence for above- and below-median precipitation in Week-2 across eastern China and the tropical Atlantic are once more tied to dynamical model consenus.
Forecasts over Africa are made in coordination with the CPC international desk, 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.