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

Last Updated - 10.21.16 (Update)

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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
Above Average Temperatures KMZ / KML / SHP KMZ / KML / SHP
Below Average Temperatures KMZ / KML / SHP KMZ / KML / SHP

Global Tropical Hazards/Benefits Assessment

Global Tropics Hazards and Benefits Outlook Discussion

Updated discussion
Last Updated: 10.21.16 Valid: 10.22.16 - 11.01.16
A weak MJO signal persisted according to the Wheeler-Hendon RMM index and the CPC index based on the 200-hpa velocity potential. The GFS model continues to indicate an increase in amplitude of the MJO index across the western Hemisphere, but there is no support for this solution from the Canadian and ECMWF ensemble members. Changes to the previous outlook, released on October 18, are based on the latest GFS, CFS, and ECMWF models along with considerations of the evolving low-frequency base state.

As of October 21, an area of low pressure, centered several hundred miles south-southeast of Cape Hatteras, North Carolina, is expected to merge with an approaching cold front and chances for tropical cyclcone development across the western Atlantic have decreased. A surface trough is likely to bring above-average rainfall to the southeast Bahamas, Turks and Caicos, and parts of Hispaniola from October 22 to 25.

The ITCZ, from 10-15N in the east and central Pacific, remains convectively active. Based on satellite imagery and model consensus, above-average rainfall is favored for parts of the east Pacific and also southwest of the Hawaiian Islands. A broad area of low pressure is located a few hundred miles southwest of the Gulf of Tehuantepec and environmental condtions are forecast to favor tropical cyclone development across the east Pacific (10-20N/100-115W) by October 25.

A brief amplification of an upper-level trough over the eastern United States is forecast to push a cold front south into the Caribbean Sea by October 26. This frontal boundary is expected to provide the focus for a continuation of above-average rainfall across parts of Hispaniola and also eastern Cuba and Jamaica from October 26 through November 1. An amplified upper-level trough near the West Coast of the United States coupled with enhanced moisture from the east Pacific is likely to result in above-average rainfall across California and parts of the east Pacific from October 26 to November 1. Elsewhere, cooler-than-normal SSTs favor below-average rainfall across the equatorial central Pacific through the beginning of November.

The previous discussion released on October 18 follows.
The MJO signal remained weak during the past week, according to the Wheeler-Hendon RMM index and the CPC index based on the 200-hpa velocity potential. The base state may be interfering with a MJO signal that is attempting to propagate east across the Pacific Ocean. Dynamical model forecasts provide varying outcomes with the evolution of the MJO as the base state continues to play a significant role. Therefore, uncertainty remains high on how much influence the MJO has on anomalous convection or mid-latitude teleconnections during the next two weeks.

During the past week, a pair of typhoons developed in the West Pacific. Typhoon Sarika crossed the northern provinces of the Philippines on October 15 and 16 with high winds and heavy rainfall. Typhoon Sarika continued to track east across the South China Sea and made a second landfall on Hainan Island on October 18. As Sarika struck the Philippines, another tropical cyclone, Haima, developed in the West Pacific and rapidly intensified. As of October 18, Typhoon Haima is approaching the northern Philippines with maximum sustained winds of 130 knots. The aforementioned tropical cyclones are likely to bring above-average rainfall to the northern Philippines, Taiwan, and southern China during the next week. The GFS model indicates rainfall amounts locally exceeding 200mm across coastal areas of southeast China.

Following an active first half of the month, tropical cyclone development is not favored across the West Pacific during the next two weeks. A short-lived tropical cyclone may develop in the northeast Bay of Bengal early in Week-1, but chances are too low to highlight an area on the map. Elsewhere, a low chance of tropical cyclone development exists across the east-central Pacific (10-15N/135-145W) during the next five days. An area of low pressure, currently northeast of the Turks and Caicos, is forecast to intensify and become a subtropical or tropical cyclone as it moves north early in Week-1. This disturbance is forecast to interact with a cold front and remain offshore of the eastern United States.

The highest confidence for above-average rainfall during Week-1 exists across areas that are likely to be influenced by tropical cyclones, including the northern Philippines, Taiwan, southern China, and the western Atlantic. The ITCZ is expected to remain convectively active near 10 degrees N in the east-central Pacific with suppressed convection closer to the equator. The base state and model consensus favors below (above)-average rainfall across southeast India, Sri Lanka, and parts of the southern Indian Ocean (parts of the Maritime Continent and equatorial Indian Ocean).

The GFS model remains most bullish with a strengthening MJO signal over the Western Hemisphere during Week-2. This solution has some support from Canadian and ECMWF ensemble members. An amplifying trough, near the East Coast of the United States, is expected to result in a cold front pushing well south into the southeast Bahamas and Cuba by the beginning of Week-2. This residual boundary along with a potential contribution from the MJO elevate the chances for above-average rainfall across parts of Cuba, Hispaniola, Jamaica, and the Caribbean Sea. The favored areas of anomalous rainfall across the remainder of the global tropics are generally related to the base state and model consensus.

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.

Product Description

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.

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 last modified: 22-Jul-2016 3:57 PM EDT
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