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

Last Updated - 06.22.21 (Routine)


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Tropical Cyclone Formation KMZ / KML / SHP KMZ / KML / SHP
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Above Average Temperatures KMZ / KML / SHP KMZ / KML / SHP
Below Average Temperatures KMZ / KML / SHP KMZ / KML / SHP

Global Tropics Hazards and Benefits Outlook Discussion

Last Updated: 06.22.21 Valid: 06.23.21 - 07.06.21
Little evidence is apparent to support the presence of an active Madden-Julian Oscillation (MJO) event at this time, with the global tropical circulation instead being dominated by a pair of atmospheric Kelvin waves that are roughly 180 degrees out of phase with one another. The RMM index is having difficulty in capturing the intraseasonal state of the tropics, and reflects a transitioning signal from emphasizing the Kelvin wave currently approaching the Date Line to the other presently near the Prime Meridian. The ECMWF ensembles consistently highlight the latter Kelvin wave, projecting onto Phases 1 and 2 over the next two weeks. The GEFS generally does this as well, but has substantially more spread than the ECMWF ensembles, particularly in RMM1 space, where the 2-week forecast varies by up to 6 units (i.e. concluding over Africa or the Maritime Continent). Altogether the lack of an apparent MJO, the two Kelvin waves being 180 degrees out of phase, and large spread in GEFS RMM forecasts underscore the limited predictability and decreased confidence in the upcoming forecast. Despite this, the Kelvin waves are likely to increase tropical cyclogenesis chances over the East Pacific through late Week-1 and over the West Pacific during Week-2.

During the past week three tropical cyclones (TCs) developed. The first to form was Tropical Storm Dolores, near 14N/101W on June 18th. Dolores attained a peak intensity of 60 knot winds on the 19th shortly before making landfall near the border of Colima and Michoacan in Mexico. Elsewhere, Tropical Storm Claudette formed near 30N/91W late on June 18th just prior to landfall along the Central Gulf Coast. Claudette brought up to a foot of rainfall to the region, and caused a dozen fatalities across Alabama due to falling trees and poor road conditions leading to auto accidents. Lastly, Tropical Storm Six formed near 11N/148E on June 21st. Tropical Storm Six is forecast by the Joint Typhoon Warning Center to recurve northward along roughly the 140th parallel through the weekend, with some accompanying intensification during the next few days.

The NHC is currently monitoring disturbances with the potential to undergo tropical cyclogenesis over both the Atlantic and East Pacific. Over the Atlantic, an easterly wave located approximately 500 miles east of the Windward Islands is given a 20% chance of becoming a TC over both the next 2 and next 5 days by the NHC's 2 PM EDT outlook on June 22nd. While development appears unlikely with this system, it could bring needed precipitation to the Virgin Islands and Puerto Rico to help drought-stricken areas. Elsewhere in the Atlantic, while climatologically early easterly waves exiting Africa have been strong thus far during 2021, with a nonzero chance of something developing over the Main Development Region late in Week-1 or during Week-2. A handful of GEFS members also support the possibility of a disturbance tracking from the southwestern Caribbean to near the Yucatan Channel by the end of Week-1, although this remains an outlier among guidance. A disturbance over the East Pacific is anticipated to have more favorable odds to develop by the NHC, with a 30% (80%) chance of forming during the next 48 hours (5 days) as of 2 PM EDT on the 22nd. This translates to high confidence for genesis during Week-1. Later in Week-2, the presence of an atmospheric Kelvin wave is likely to bring a favorable large-scale environment, which when coupled with the typical East Pacific climatology supports moderate confidence for TC formation similar to the region being monitored during Week-1. The presence of a Kelvin wave and forecast Rossby wave activity also result in moderate confidence for TC formation over the Philippine Sea during Week-2. While not on the forecast map, a handful of GEFS members do show surface troughing possibly developing into a closed circulation over the far southwestern Caribbean this weekend while drifting toward the northwest. This system could be in the vicinity of the Yucatan Channel by the start of Week-2 if it were to develop, but confidence is low for such a scenario.

The precipitation outlook during the next two weeks is largely based on a consensus among the CFS, GEFS, and ECMWF ensemble means, anticipated TC tracks, and large-scale modes of tropical variability. Reforecast guidance supports the potential for above-normal temperatures across portions of the northwestern U.S. the next two weeks (high confidence), parts of Africa and Europe during Week-1 (high confidence), and parts of Africa, Europe and the Middle East during Week-2 (moderate confidence). This is in addition to reforecast guidance supporting a high risk for much below-normal temperatures that could lead to a frost or freeze across portions of Argentina, Bolivia, Brazil, Paraguay, and Uruguay during Week-2. Some of the cold weather anticipated could impact coffee-growing regions across parts of southern Brazil, while ECMWF reforecast guidance gives up to an 80% chance for daily record lows to be observed in portions of Bolivia. For hazardous weather concerns across the U.S., please refer to regular tropical updates from the NHC, as well as your local NWS Forecast Office, the Weather Prediction Center's Medium Range Hazards Forecast, and CPC's Week-2 Hazards Outlook. Forecasts over Africa are made in consultation with the International Desk at CPC 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 at 2 PM local Eastern Time 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: 2-Jun-2021 12:03 PM EDT
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