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GTH Outlook Map and Data
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Last Updated -
01/14/25
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GTH Outlook Discussion
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Last Updated -
01/14/25
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Valid -
01/22/25 - 02/04/25
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After becoming incoherent by the start of 2025, RMM observations show the Madden-Julian Oscillation (MJO) sharply regaining amplitude while beginning to resume its eastward propagation during the past week. Analysis of upper-level velocity potential anomaly fields show the competing tropical modes, which had weakened the MJO earlier this month, still appear to be at play. However, the recent reorganization of subseasonal activity is evidenced by the return of a more spatially continuous area of enhanced divergence aloft from the eastern Pacific to the Prime Meridian, and based on the CFS, GEFS and ECWMF ensembles, a more canonical wave-1 pattern is favored to redevelop throughout the global tropics. RMM forecasts have been consistent in depicting this MJO reemergence, and in fact, models are now unanimous in favoring a high amplitude event that propagates from the Western Hemisphere and reaches the Maritime Continent in the coming weeks. Perhaps of greater note is the accelerated phase speed depicted in RMM space, which points to Convectively Coupled Kelvin Wave (CCKW) activity constructively interfering with the main MJO convective envelope. With the MJO propagating across the Indian Ocean and Maritime Continent later during weeks 2 and 3, any constructive interference also looks to be reinforced by the low frequency convective footprints associated with an emerging La Nina, where both the enhanced and suppressed envelopes become more in-phase with one another. Consequently, this may trigger a Westerly Wind Burst (WWB) event in the Indian Ocean, as well as initiate another trade wind surge event over the equatorial Pacific which could possibly bring stronger La Nina conditions later this winter.
Given the favored constructive interference of these tropical modes, the large-scale environment is likely to be favorable for Tropical Cyclone (TC) development in the Indian Ocean, with decreased chances for genesis in the South Pacific. While the MJO is favored to lose some amplitude as it reaches the Maritime Continent during the week-3 timeframe, conditions may become more favorable for TC development in the western Pacific, despite a less active climatology. For the extratropics, an eastward propagating Indian Ocean and Maritime Continent MJO also historically favors a warmer response over much of the central and eastern CONUS, though this continues to be somewhat at odds with the dynamical model guidance, which instead maintain a full latitude ridge over western North America to promote the advection of Arctic air downstream through the middle of week-2. While novel, there are indications in the latest ensemble guidance of the longwave trough retrograding over North America, allowing more ridging and warming temperatures over the eastern CONUS closer towards the end of January.
Two TCs formed during the past week. After forming in the South Pacific on 1/11 near 12S/167W, TC Pita peaked at 40kts before quickly dissipating over open waters on 1/12. In the southwestern Indian Ocean, TC Dikeledi formed on 1/9 to the east of Madagascar and has tracked westward and made landfall over the Nampula province of northern Mozambique bringing locally heavy precipitation amounts during the past 24hrs. While still at Tropical Storm strength, this system has exited back into the Mozambique Channel where the Joint Typhoon Warning Center (JTWC) expects Dikeledi to gain some intensity and track southward under the steering subtropical ridge. The latest official forecast track keeps this system over open waters before eventually being absorbed by the westerlies, however parts of southern Madagascar may experience heavy precipitation and periods of high winds during the next several days.
In the wake of TC Dikeledi during week-1, models continue to favor another area of low pressure deepening in the Mozambique Channel. The ECMWF is slower with this development, compared to the GEFS, however consensus between the models and the encroaching Indian Ocean MJO supports the addition of 40% chances of TC development being posted. While probabilistic tools are not clear on individual formation areas in the south-central Indian Ocean during week-2, the westerly phase of the MJO and equatorial Kelvin activity are expected to reinforce the low frequency lower-level westerlies from 65E to 100E conducive for TC genesis. Therefore, this supports a broad area of 40% chances posted in part of the basin. Over the southeastern Indian Ocean, there is good model agreement favoring tropical low formations offshore of northwestern Australia later this week. While genesis appears most likely during late week-1, 20% chances for development are still posted to capture any delay in formation due to increased shearing favored in the model guidance. Given a lack of support in the tools and the suppressed phase of the MJO moving overhead, no TC shapes are issued over the South Pacific.
The aforementioned anomalous lower-level westerlies are favored to remain established across the equatorial Indian Ocean, supporting additional TC development during week-3. Based on extended range probabilistic tools, the greatest chances for formation exist across the south-central and south-eastern Indian Ocean where 20% chances are issued. Increased chances for genesis also exist over the Mozambique Channel, however it is unclear whether these signals are related to residual signals stemming from week-2. 20% chances for development were also considered for the western Pacific based on the development of lower-level westerlies tied to the MJO, however tool signals remain too marginal to include any TC related shapes in the region.
The above and below normal precipitation outlooks for weeks 2 and 3 are based on the anticipated continuation of the La Nina base state, anticipated TC tracks, phase 2-4 MJO composites for Dec-Feb, as well as a historical skill weighted blend of GEFS, CFS, and ECMWF ensemble forecast systems. For the CONUS, below-normal temperatures are favored for much of the eastern two thirds of the country associated with the aforementioned full latitude ridge favored over Western North America. Conversely, above-normal temperatures and excessive heat conditions are possible over parts of equatorial Africa, as well as over portions of Australia where daytime maximum temperature may exceed 105 degrees F (40 degrees C) during week-2. For hazardous weather concerns in your area during the next two weeks, please refer to your local NWS office, the Medium Range Hazards Forecast produced by the Weather Prediction Center, and the Week-2 Hazards Outlook from CPC. 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 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.
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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.
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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.).
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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.
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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.
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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.
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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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Product Resources
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Feedback and Questions
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www.nws.noaa.gov
