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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 - 03.24.15 (Routine)

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: 03.24.15 Valid: 03.25.15 - 04.08.15
CORRECTION - Sent at 1732 ET.

Corrects Confidence for Tropical Cyclone formation shape in Southern Indian Ocean. Change to High from Moderate.

Original discussion follows.

Both of the RMM based and the CPC velocity potential indices continue a robust MJO signal. The area of enhanced convection indicated by both measures is over the Americas. Spatial plots of upper-level velocity potential show enhanced divergence waning over the Central Pacific and increasing over Africa, with convergence increasing over the West Pacific. Little to no convection is evident over the Indian Ocean and the western North Pacific. Westerly wind anomalies are evident in the low levels from the Date Line to the the East Pacific, while easterly anomalies are present from Africa to the Maritime Continent. The recent, high amplitude MJO signal is likely to fade in the coming days, although that may take up to 2 weeks. OLR measurements indicate the influence of an Equatorial Rossby Wave (ERW) near the Date Line, a Kelvin Wave (KW) over the Americas, and the low frequency state, all of which are likely to influence the pattern of convection during the next 2 weeks.

Dynamical model forecasts of the MJO indicate continued propagation and some weakening during Week-1, with some models almost completely damping the signal by Week-2. Statistical models are in agreement with this, except for the Constructed Analog method, which indicates a strong signal through the end of Week-2. That scenario is less likely given the upper-level pattern. During the next 2 weeks, the MJO is likely to become less influential than the low frequency state.

Tropical Storm Reuben developed over the South Pacific on March 21, and was relatively short lived. Tropical Cyclone Nathan moved from the South Pacific to the South Indian Ocean, crossing over portions of northern Australia. Tropical Cyclone Nathan is expected to weaken during the next 24-48 hours. During the next 2 weeks, tropical cyclone formation odds are increased over the South Pacific, east of the Date Line, and across the western North Pacific from about 130E to 160E. Late in Week-1 and into Week-2, the KW over the Americas could slightly enhance odds of tropical cyclone formation over the central South Indian Ocean.

During Week-1, model guidance, MJO composites, and the low frequency state favor above average rains over the eqautorial Central Pacific, with extensions into the South Pacific along the SPCZ and into the western North Pacific along 10N. Model output and MJO composites also favor some increased precipiation over portions of Central America and western South America, although those signals are transient and weaker. Below average rains are supported by models, MJO composites, and the background state over the Maritime Continent.

By Week-2, the MJO signal is likely to be much weaker than it is now, with the background state supporting enhanced (suppressed) convection near the Date Line (Maritime Continent and Australia). Above average rains are likely over the central Indian Ocean as the KW and any remaining MJO signal are likely to transit the area during that time, although the uncertainty there is high because of the destructive interference from the low frequency state.

For both weeks, shapes depicted over Africa are a result of coordination with CPC's Africa Desk, and account for model guidance and the state of the MJO.

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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