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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 - 08.29.14 (Update)


\"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 Tropical Hazards/Benefits Assessment

Global Tropics Hazards and Benefits Outlook Discussion

Updated discussion
Last Updated: 08.29.14 Valid: 08.30.14 - 09.09.14
The MJO remains largely incoherent with the large-scale velocity potential anomaly field exhibiting a wave-2 pattern. Changes to the forecast involve fairly major changes in the Atlantic, where model guidance currently suggests a low to moderate risk of TC formation over parts of the western Caribbean and Bay of Campeche. Elsewhere in the Atlantic, odds for TC formation are generally diminished with respect to the initial outlook. There is a decidedly low risk of cyclogenesis over the main development region (MDR) during the remainder of Week-1, though there are elevated odds for above-average rainfall in that region. In Week-2, odds for TC formation remain elevated in the far eastern Pacific near the coast of Mexico. Model guidance currently suggests that any TC formation in the Atlantic would be fairly far north, though the probability of formation appears to be low enough to warrant removal of the moderate risk in that region.

The precipitation shapes have been updated to reflect the latest model guidance and some new information regarding any coherent subseasonal modes of variability.

The original forecast discussion follows:
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The MJO remained 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 slightly stronger signal than last week, although the atmosphere, at all levels, does not appear to be fully aligned with a stronger MJO. There is evidence of a slow, eastward propagation in the upper-level wind field, but at speeds slower than the MJO. Other coherent modes of subseasonal convective variability, including pronounced Rossby Wave activity, are interfering with any MJO signal. Below-average convection was recorded over the western Pacific, while above-average precipitation was observed over the central Indian Ocean and the East Pacific.

Forecasts for the MJO have a moderate amount of spread, with the GFS indicating the predominance of westward moving features, while the ECMWF, UKEMT, and other models, indicate eastward propagation of a weak signal over the Indian Ocean. Based on recent observations, the weakly enhanced convection over the Indian Ocean seems more plausible, so the forecast is largely based on that set of solutions. The MJO is not expected to play a large role in the upcoming circulation pattern.

Tropical Storm Cristobal formed near the Bahamas, and Tropical Depression Karina and Hurricane Marie continue to spin over the eastern Pacific. During the next 5 days, Tropical Storm Cristobal is forecast to intensify to hurricane strength and propagate rapidly north, then northeast, passing just west of Bermuda. Hurricane Marie is likely to move northwest, then northward during the next 5 days, with longer range predictions indicating a path toward the California coast, although in a much weakened, barely identifiable state.

Over the Atlantic, a tropical wave about 900 miles east of the Lesser Antilles is moving west, and has a 20% chance of development during the next 5 days. Beyond that, the chances of development are above average for the area near the Greater Antilles. A strong easterly wave is forecast to move off the west coast of Africa later in Week-1, increasing the threat of tropical cyclone formation over the Central Atlantic. That threat continues into Week-2, with support from dynamical models and some statistical tools based on MJO phase. No tropical cyclone development is forecast for the East Pacific during Week-1, with formation odds increased for the area east of 110W during Week-2.

During Week-1, suppressed convection is likely over the western North Pacific and portions of South Asia as the entire Asian Monsoon circulation continues to be weak. Some enhanced convection is likely across the Maritime Continent. Above-average rains are likely over the East Pacific and Atlantic, associated with tropical cyclones and a slightly enhanced ITCZ southeast of Hawaii.

Suppressed convection is likely to continue over the western North Pacific during Week-2. Enhanced rains are likely over the eastern Pacific, between 120W and 90W, as well as over the Maritime Continent, with the most likely area of enhanced rainfall along the equator.

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 last modified: 9-Jun-2014 3:37 PM EDT
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