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Global Tropics Benefits/Hazards
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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.
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Last Updated - 09.09.22 (Update)
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Global Tropics Hazards and Benefits Outlook Discussion |
| Last Updated: 09.09.22 |
Valid: 09.10.22 - 09.20.22 |
Updated discussion
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Convection in the tropics has become slightly disorganized in the past few days. The main convective envelope remains over the Maritime Continent but the wave-1 pattern seen on Sept. 5 is breaking down with incoherent structure in the Western Hemisphere. Looking ahead there is a lot of uncertainty as to the state of the Madden Julian Oscillation (MJO) in the coming weeks. Most dynamical forecast model depictions in RMM space suggest weak MJO activity for the next two weeks, with the index staying within the unit circle for most model solutions, as well as little agreement on future propagation of the convective envelope during the forecast period.
There has been no tropical cyclone (TC) genesis since Sep 6. Looking ahead, for the day 1-4 period an area of moderate confidence in TC genesis over the Main Development Region (MDR) in the Atlantic Ocean has been removed consistent with the latest update from the National Hurricane Center (NHC), which has several areas of interest in the MDR but all with less than 40% confidence in TC formation in the next 5 days. Two areas of moderate risk for TC formation in the West Pacific remain in place, consistent with ECMWF model solutions and Joint Typhoon Warning Center (JTWC) outlooks. For the day 5-14 period, areas of moderate risk for TC genesis remain in place for the East and West Pacific basins, as well as the Atlantic MDR, consistent with guidance from ECMWF and GEFS ensembles.
Areas of forecast above and below normal precipitation have been tweaked slightly from the Tuesday map as well, consistent with model guidance, but are broadly the same as before. In the day 1-4 period the area of below-normal precipitation over the Philippines has been expanded slightly eastward. For the day 5-14 period, areas of above- and below-average precipitation along the Equatorial Pacific Ocean have been expanded to reflect the latest model solutions.
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Following an amplification of the Madden Julian Oscillation (MJO) over the Indian Ocean in late-August, the intraseasonal signal has since retreated back into the RMM-based unit circle. The low frequency La Nina base state remains the dominant mode of variability in the tropics, with a wave-1 asymmetry evident in the spatial upper-level velocity potential field. Enhanced convection is located across the Indian Ocean, Maritime Continent, and far Western Pacific, with suppressed convection over much of the Western Hemisphere. The GEFS and ECMWF ensembles depict little eastward propagation of the convective envelope, consistent with a weakened MJO. Kelvin Wave activity may promote tropical cyclone (TC) development across the Eastern Pacific and Atlantic Basins during the next 2 weeks, coinciding with the climatological peak of hurricane season.
TC activity increased across the Atlantic Basin during the first week of September following the first August since 1997 without a named storm in the Atlantic. Hurricane Danielle formed on 9/1 across the higher latitudes of the Central Atlantic. The system poses no threat to land and is forecast to track northeastward and lose tropical characteristics later this week. Tropical Storm Earl formed on 9/3 to the east of the northern Leeward Islands. It is expected to recurve northeastward over the western Atlantic, perhaps skirting Bermuda. Conditions are favorable for intensification and NHC forecasts the system will become the season’s first major hurricane. The Eastern Pacific Basin has been active as well. Tropical Storm Javier developed on 9/1 and tracked to the west of Baja California, with outer rain bands impacting parts of the peninsula. Hurricane Kay formed on 9/4 and is forecast to take a similar track to Javier, close to Baja California, and strengthen into a major hurricane. The system is also forecast to contribute to an increase in moisture and subsequent heavy rainfall over parts of the western U.S. later this week. TC activity is forecast to continue over the Atlantic Basin, with the NHC forecasting a 60 percent chance of TC development over the east-central Atlantic in the next 5 days, corresponding with a moderate confidence area for week-1. Additional easterly waves emerging off of Africa favor increased chances of TC development continuing into week-2, with an additional moderate confidence area posted for that period. Dynamical models are also indicating TC development over the East Pacific during week-2 following a short break in activity, and a moderate confidence shape is highlighted off the western coast of Mexico.
During the past week, Super Typhoon Hinnamnor tracked across the western North Pacific. The system weakened before recurving north into the Sea of Japan, skirting South Korea before undergoing extratropical transition. A short-lived Tropical Depression (13W) developed behind Hinnamnor on 8/30, but was ultimately absorbed by the former system. Tropical Depression 14W developed on 9/6 over the Western North Pacific with the Joint Typhoon Warning monitoring Invest 92W for potential development in the coming days in the same general area as 14W. Therefore, a corresponding moderate confidence for TC development is included in today’s outlook. An additional moderate risk for TC formation is indicated to the east (~160degE) supported by the ECMWF ensembles which depict a northeastward tracking TC late in week-1. Although outside of climatology, several tropical depressions have developed over the Bay of Bengal during the month of August, and favorable conditions suggest that this enhanced activity may continue, supporting a moderate confidence for TC development over the Bay of Bengal for week-1. TC activity is forecast to continue over the West Pacific through week-2, with a moderate confidence region highlighted in the climatologically favored area east of Taiwan and the northern Philippines.
The precipitation and temperature outlooks during the next two weeks are based on a consensus of GEFS, CFS, and ECMWF model solutions, potential TC tracks, and La Nina precipitation composites. A deep tropical moisture plume is forecast to bring several inches of rain to parts of the Southeast U.S. and northern Florida during week-1, with the nearly stationary convective envelope over the Indian Ocean and Maritime Continent favoring heavy rainfall across parts of India and southeastern Asia. Anomalously warm temperatures are likely over the western U.S. during week-1, with moderation forecast later in the period as the increased moisture from the remnants of Kay pushes northward. For hazardous weather concerns in your area during the next two weeks, please refer to your local NWS office, the Medium Range Hazards Forecast from the Weather Prediction Center (WPC), and the CPC Week-2 Hazards Outlook. Forecasts issued over Africa are made in coordination with the International Desk at CPC.
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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:
- 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
- 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)
- 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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