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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 - 09.02.14 (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: 09.02.14 Valid: 09.03.14 - 09.17.14
The MJO remained fairly weak as the atmospheric circulation is not exhibiting a pattern coherent with a strong MJO. The CPC Velocity Potential Index and the Wheeler-Hendon RMM Index both indicate a weak signal consistent with convection centered in the eastern Indian Ocean (IO) and Maritime Continent. There continues to be some evidence of a slow, eastward propagation in the upper-level wind field, but at speeds slower than the MJO. This is also generally true of the OLR field, in which an envelope of suppressed convection has propagated slowly across the Maritime Continent and West Pacific over the last few weeks. Other modes of variability, including equatorial Rossby waves, continue to interfere with the MJO signal, but are not as strong as in weeks past.

Forecasts for the MJO have a moderate amount of spread, with the GFS indicating the predominance of westward moving features, while the ECMWF, Canadian, and JMA, indicate eastward propagation of a weak signal over the Maritime Continent into the far western Pacific. Based on recent observations, the eastward propagation of a weak signal is the preferred solution. The MJO is thus expected to play a small role in the pattern of tropical convection over the next couple of weeks.

Tropical Storm Dolly formed in the Bay of Campeche and is forecast to make landfall in Mexico this evening. Tropical storm Norbert formed in the East Pacific, and is forecast to move northwestward, passing west of Baja California.

Over the Atlantic, tropical cyclone formation is most likely over the far eastern part of the basin later in Week-1, with the current 5-day probability of formation at 30%. Any storm that forms in this region is likely to recurve well to the east of North America. This threat lingers into Week-2, since formation might not occur until next Tuesday or Wednesday. Also, another wave could emerge from Africa by then, with some chance of formation. Again, the forecast tracks of these potential systems appear to be into the North Atlantic. There is some risk of formation in the western Caribbean/Bay of Campeche later in Week-1, but elevated vertical wind shear and model disagreement suggest that the threat is too low to warrant depiction on the map. This threat will be closely reevaluated on Friday with the GTH update.

In the Pacific basins, tropical cyclogenesis is moderately likely east of the Philippines, as a more organized disturbance in the monsoon trough is forecast to move northward, then northeastward, potentially developing into a tropical cyclone. In the East Pacific, there is a low risk of formation in Week-2, though the weak MJO and enhanced wind shear argue against cyclogenesis. However, models indicate enhanced convection in this region, consistent with atmospheric Kelvin waves moving eastward ahead of the main envelope of convection forecast across the West Pacific.

During Week-1, suppressed convection is likely over the central and eastern IO extending to the western Maritime Continent. Some enhanced convection is likely from Southeast Asia to the eastern Maritime Continent based on model guidance and consistent with weak MJO activity. Above-average rains are likely over the East Pacific and western Caribbean, associated with tropical cyclones and an enhanced monsoon trough over the western Caribbean. The latter could be the source of the aforementioned TC threat later in Week-1. Model consensus strongly indicates drier-than-average conditions over the central and western Atlantic, south of possible TC activity. This suggests that the area for TC formation would be shifted north relative to average.

Suppressed convection is likely to shift eastward across the Maritime Continent in Week-2, consistent with model guidance and any weak MJO progression. Likewise, enhanced convection is expected to shift northeastward across the West Pacific. Above-average rainfall is expected across the East Pacific, consistent with enhanced Kelvin wave activity and model guidance.

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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