A few factors are pointing toward an MJO event organizing over the Indian Ocean (Phase 2 of the RMM index phase space). Most model solutions have a signal continuing into Phase 3, with some continuing a signal into Phase 4. The disagreement on the eastward propagation leads to increased uncertainty for days 5 through 11 (the remainder of Week-2).
During the past couple of days, Tropical Storms Frank and Georgette formed over the eastern Pacific, while Tropical Storm Estelle transitioned to a post-tropical storm. Odds for further tropical cyclone formation over the central or eastern Pacific are not elevated during the next 11 days. Tropical cyclone formation odds increase over the western North Pacific, north of 15N during the next week. The MJO, in Phase 3, would not favor tropical cyclone activity further south over the western North Pacific. This area will be monitored for any increasing threat, further out in time, should a robust MJO signal continue into Phase 5.
Modifications to the areas indicated for above average rainfall were made to reflect the latest tropical cyclone track forecasts. Model forecasts also helped shape the areas where tropical cyclones are not expected to go during the next 11 days.
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Some measures have the MJO strengthening during the past week, but other measures do not. The signal that the RMM index and the CPC velocity potential index are indicating as strengthening are potentially an emerging MJO, though without consistent propagation, the current event cannot yet be labeled as a full instance of an active MJO. Model forecasts indicate a slight strengthening over Africa, followed by some eastward propagation to the Indian Ocean/western Maritime Continent. The signal then weakens the end of Week-2. Model agreement on that forecast scenario is good, so uncertainty is lower than last week.
During the last week, Tropical Storm Estelle developed over the eastern Pacific, continuing an active season there. Currently, the accumulated cyclone energy in the eastern and central Pacific is 231 percent of normal, while the western North Pacific is 42 percent of normal. Tropical cyclone 01S (Abela) developed over the southern Indian Ocean and moved toward Madagascar. The cyclone is forecast to weaken to less than tropical cyclone strength by July 20, at 6Z. During the next two weeks, tropical cyclone formation odds are increased relative to normal over the East Pacific, with that signal peaking during Week-1 and lessening during Week-2. Tropical cyclone formation chances are also increased over the western North Pacific during Week-2. Some models are indicating slight increase in the chances for tropical cyclone formation over the eastern tropical Atlantic Ocean during the middle of Week-2, though confidence is low in that occurring.
Tropical cyclones are expected to contribute to above average rainfall over the eastern Pacific, with some slightly enhanced odds of heavy rains impacting Hawaii during Week-1. An emerging MJO is likely to contribute to enhanced rains over eastern Africa and eventually the Indian Ocean and Maritime Continent. The South Asian Monsoon is likely to continue with a break in the rainfall during Week-1, with some recharge hinted at in Week-2. Below (above) average SST values are likely to support suppressed (enhanced) rainfall over the equatorial central Pacific (South Pacific).
During Week-2, some recharge in the South Asian Monsoon is likely, with below average rains pushing northward toward northern Thailand and northwest India. Enhanced rainfall is likely to continue near Hawaii, and over the South Pacific, while below average SST values are likely to support suppressed rainfall over the equatorial central Pacific.
Forecasts over Africa are made in consultation with CPCs 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.