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HOME > Climate & Weather Linkage > Global Tropics Benefits/Hazards

Beginning June 6, 2014, CPC will be issuing an operational update of this product every Friday by 1 PM ET to further support the NWS regions. The update will only span 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 will not extend the time horizon of the product, but rather apply 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.

Last Updated - 07.29.14 (Routine)


\"Global
GIS Ready Formats
 
Tropical Cyclone Formation KMZ / KML / SHP KMZ / KML / SHP
Upper Tercile Precipitation KMZ / KML / SHP KMZ / KML / SHP
Lower Tercile Precipitation KMZ / KML / SHP KMZ / KML / SHP

Global Tropics Hazards and Benefits Outlook Discussion

Last Updated: 07.29.14 Valid: 07.30.14 - 08.13.14
The MJO remained generally incoherent during the previous week, as other modes of anomalous tropical convection continued to dominate the pattern. The amplitude of the RMM Index increased during the past several days, as a large scale dipole of enhanced convection over the Pacific and suppressed convection over the equatorial Indian Ocean and Maritime Continent projected strongly onto Phase-7 of the Wheeler-Hendon diagram. The CPC velocity potential index remains fairly weak, however, despite a corresponding robust Wave-1 type VP anomaly pattern observed over the global tropics during the past few days. A strong Kelvin Wave currently propagating over the Atlantic is interfering with the signal, which may be contributing to the weakness in the CPC index. Little eastward propagation of the enhanced convection over the Pacific is evident, as the signal is comprised primarily of higher frequency modes such as Kelvin Waves and tropical cyclones.

Many dynamical models including the GFS, ECMWF, Canadian, and Japanese, favor a rapid eastward propagation of the MJO signal, with increasing amplitude over the Indian Ocean or Maritime Continent by Week-2. This phase speed is inconsistent with MJO activity, and more suggestive of a model response to the Kelvin Wave currently propagating over the Atlantic. Anomalous upper-level westerly wind anomalies are currently observed over Africa and the Indian Ocean, which would tend to inhibit outflow necessary for the development of robust MJO-related tropical convection. Statistical models such as the Constructed Analog favor eastward propagation of the current signal over the Pacific. Based on recent observations, the future evolution of any MJO signal is highly uncertain.

Two tropical cyclones developed over the eastern Pacific during the past week. Tropical Storm Genevieve developed on July 25, followed by Hurricane Hernan on July 26. Both systems weakened over open water, although the remnants of Genevieve are moving through an area that is somewhat conducive for potential redevelopment. Typhoon Halong developed east of Guam on July 28, and is currently forecast to intensify while passing near or just north of Guam. Model forecasts indicate a recurving track for Halong, with potential impacts for Japan later in the Week-1 period.

A tropical wave over the central Atlantic has become increasingly organized during the past two days, and there is a high probability for tropical cyclone formation during the Week-1 period. Most model forecasts indicate a recurving track over the central Atlantic. Over the eastern and central Pacific, several areas embedded in an active ITCZ are favored for potential tropical cyclogenesis, including one or more systems south or southeast of Hawaii. This activity may contribute to enhanced seas or rainfall near the Hawaiian islands. Further west, there is a high confidence potential for tropical cyclone development associated with a monsoon low east of the Philippines. Model forecasts bring this potential system into the East China Sea during the Week-1 period.

During Week-1, enhanced convection, partly associated with tropical cyclone activity, is favored over the northwestern Pacific from the northern Philippines eastward to 150E. Enhanced convection is also favored near and south of Hawaii, extending eastward along the ITCZ. Enhanced North American Monsoon activity is also favored, with areas of heavy rainfall possible over northwestern Mexico and southwestern New Mexico. Dynamical models favor suppressed convection across southern India, the eastern Indian Ocean, the Maritime Continent, and the equatorial West Pacific.

There is decreased confidence for the Week-2 outlook due to uncertainty regarding the evolution of the global tropical pattern. The GFS and CFS favor a continuation of enhanced convection near and east of the northern Philippines during Week-2, with suppressed convection forecast north of New Guinea. Enhanced convection is also possible across the eastern Pacific east of Hawaii, especially if there are any ongoing tropical cyclones. Several GFS ensemble members indicate a potential for tropical cyclone development over the western Pacific east of 150E during Week-2.

Forecasts of enhanced or suppressed convection across some parts of Africa are based on regional scale anomaly features and were produced based on collaboration with the CPC 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.

Product Description

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.

Product Purpose

The product supports the NOAA mission in three primary ways:

  1. 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
  2. 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)
  3. 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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Page Author: CPC Web Team
Page last modified: 9-Jun-2014 3:37 PM EDT
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