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HOME > Climate & Weather Linkage > Global Tropics Outlook


Weeks 2-3 Global Tropics Hazards Outlook (GTH)

For week-1 tropical cylone information and forecasts, please visit the National Hurricane Center and the Joint Typhoon Warning Center. For week-1 precipitation and temperature related products, please visit the Weather Prediction Center or refer to your local NWS office.

ATTENTION:

The Climate Prediction Center is soliciting comments from August 1, 2023 through December 31, 2024 on the implementation of the Week 2 and experimental Week 3 Global Tropics Hazards Outlook.

Here is the Survey.


GTH Outlook Map and Data
Last Updated - 04/09/24
GIS Ready Formats
Hazard
Tropical Cyclone Formation Probability KMZ KML SHP KMZ KML SHP
Enhanced Precipitation Probability KMZ KML SHP KMZ KML SHP
Suppressed Precipitation Probability KMZ KML SHP KMZ KML SHP
Above Average Temperatures Probability KMZ KML SHP KMZ KML SHP
Below Average Temperatures Probability KMZ KML SHP KMZ KML SHP

Tropical Cyclone Only GTH Map
Precipitation Only GTH Map
Temperature Only GTH Map
Lines Only GTH Map

Latest Product (PDF Format)
Latest Briefing (PDF Format)
GTH Archive
 
GTH Outlook Discussion
Last Updated - 04/09/24
Valid - 04/17/24 - 04/30/24
Since propagating eastward from the western Hemisphere, objectively filtered tropical wave analysis of upper-level velocity potential anomalies shows that the Madden-Julian Oscillation (MJO) encountered strong destructive interference with Equatorial Rossby Wave (ERW) activity since late March. This likely resulted in a slowed and weakened signal in the RMM observations, though continued eastward propagation of the MJO signal over the Indian Ocean remains evident in RMM space, where the enhanced phase has entered the Maritime Continent (phase 4). Notably, the strong ERW activity led to an uptick lower-level westerlies observed over the equatorial Pacific, which not only eroded the enhanced trades associated with the suppressed phase of the MJO crossing the Date Line, but also may have implications on the transitioning El Nino state by delaying or suppressing much of the subsurface cooling ongoing in the basin.

Looking ahead, RMM forecasts generally favor weaker and less coherent intraseasonal activity with several dynamical model ensemble means crashing the MJO signal into the unit circle. While some ensemble member solutions continue to point to continued eastward propagation into the western Pacific at a higher amplitude, the overall predicted weakening of the MJO appears to be tied to destructive interference with a low frequency signal developing over Africa and the western Indian Ocean. The associated large-scale convective and circulation anomalies are resemblant of a positive Indian Ocean Dipole (+IOD) akin to the event observed last fall, and while such an event is unusual during this time of year, the thinking is that these anomalies appear to be residual responses of the decaying El Nino, and are not likely to persist in the coming months. Nevertheless, the emerging low-frequency signal is non-trivial, and looks to become a more predominant driver of tropical variability, with the MJO perhaps playing less of a role moving forward. Upper-level velocity potential anomaly forecasts offer a more coherent MJO perspective than the RMM forecasts, and feature the enhanced phase of the MJO reaching the western Pacific in the next few weeks. However, compared to previous outlooks, there remains an overall larger degree of uncertainty in regards to the strength and evolution of the MJO amidst the shifting background state through the end of April.

During the past week, one Tropical Cyclone (TC) formed in the global tropics. Since forming on 4/5 in the Timor Sea, TC Olga underwent extreme rapid intensification with a wind speed increase from 50 to 100 kts in 24 hours, and peaked at category 4 strength during the past weekend. Currently located near 17S/117E as a Tropical Storm and tracking to the southwest, the Joint Typhoon Warning Center (JTWC) expects Olga to succumb to continued dry air entrainment and strong vertical wind shear, and dissipate in the next few days. However, increased winds and precipitation, with locally heavier amounts are possible over parts of western Australia early in week-1.

For TC formation potential in the coming weeks, the aforementioned ERW is expected to continue propagating westward from the Pacific and begin to constructively interfere with the enhanced convective MJO envelope over the Maritime Continent within the next week or so. This wave phasing is expected to lead to an uptick in convection and a strengthening of lower-level westerlies favorable for TC development, which is supported in the probabilistic TC genesis tools depicting increased chances for formation to the north of Australia. Although these tools show the highest odds for development during week-1, 20% chances are posted from approximately 120E to 155E should there be any delay in formation. The addition of 20% chances were considered for week-2 over a portion of the western Pacific and southwestern Indian Ocean based on these tools, however these are omitted from the outlook due to the favored prevalence of anomalous lower-level easterlies to increase shear in these regions, as well as climatology. Incidentally, late April marks the climatologically quietest time of the year for TC development globally (less than 25 TCs formed during the end of April from 1979 to 2022). In light of this, greater uncertainty with the MJO, and little to no coherence with signals in the probabilistic TC tools, no corresponding TC areas are highlighted for the week-3 period. Beyond this time, the northern Indian Ocean, western and eastern Pacific will draw more attention in the upcoming outlooks, as these basins become more climatologically active later in May.

The precipitation outlook for weeks 2 and 3 is based on a springtime ENSO composites, potential TC activity, and a skill weighted blend of GEFS, ECMWF, CFS and Canadian ensemble mean solutions, with less input from Maritime Continent and western Pacific MJO composites. For temperatures, above-normal conditions are expected to continue over parts of southern Africa, southeast Asia,and northern South America, where combined with near to below normal precipitation forecast, is expected to degrade vegetation health, worsen drought, and sustain water supply concerns for many areas in the highlighted regions. For hazardous weather conditions in the U.S. 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 made over Africa are made in coordination with the International Desk at CPC.


Product Release Information
The Global Tropics Hazards 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 Google Meet) open to all stakeholders where the latest conditions and the newly released outlook are shared with the opportunity to ask questions. Folks that are interested in learning more or attending these briefings should contact Jon.Gottschalck@noaa.gov, Scott.Handel@noaa.gov, Adam.Allgood@noaa.gov and Nicholas.Novella@noaa.gov for the required information. Each weekly outlook and GTH release briefing is Archived and available on the website.

Product Description
The Global Tropics Hazards Outlook is a probabilistic forecast for areas with elevated probabilities for above- or below-median rainfall, above- or below-normal temperatures and regions where tropical cyclogenesis is favored for the upcoming Week-2 and Week-3 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 brown respectively. Above (below) normal temperature forecast areas are depicted in orange and blue respectively. Favored areas for tropical development are shown in red. Three probability intervals are indicated for precipitation and temperature which are set at 50, 65, and 80%, while the probability intervals for tropical cyclone development are set at 20, 40, and 60%. 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 based on a number of forecast tools, many of which are objective and serve as an objective first guess. The final depiction is an assessment of these objective forecast tools augmented by the forecaster when based on additional forecast information when appropriate to create the final product. Forecast tools include MJO composites, empirical and dynamical based MJO, ERW and KW forecasts, and bias-corrected dynamical model guidance from a number of modeling systems. Tropical cyclone areas are based on MJO composites and statistical and dynamical tropical cyclone forecast guidance products 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.

Product Resources

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Page Author: CPC Web Team
Page last modified: 6-Mar-2024 12:53 PM EST
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