|
|
GTH Outlook Map and Data
|
Last Updated -
07/14/26
|
|
|
|
|
|
GTH Outlook Discussion
|
Last Updated -
07/14/26
|
Valid -
07/22/26 - 08/04/26
|
The Madden-Julian Oscillation (MJO) continues to constructively interfere with the El Nino background state through the middle of July. This is supported by a high amplitude phase 7 event (near 2 standard deviations) in the RMM phase space, with the 200-hPa velocity potential anomaly fields revealing a robust enhancement of the enhanced (suppressed) divergence envelopes over the equatorial Pacific (Indian Ocean). Despite these strong MJO signals, little eastward propagation of the MJO is evident in the RMM observations. The lack of continuous propagation looks to be attributed, at least in part to Tropical Cyclone (TC) Bavi which strengthened to a Super Typhoon and maintained a strong intensity in the western Pacific during the first week or so in July. The widespread westward shifting lower-level westerly and OLR anomalies associated with Bavi may have projected onto the RMM index, resulting in a stalled and/or westward retreating signal in RMM phase space.
Looking ahead, dynamical models generally favor the resumption of an eastward propagating MJO from the Western Pacific into the Western Hemisphere during the next week, but is followed by a gradual disorganization of the MJO signal later in July. The favored disorganization likely marks the early stages of the subseasonal activity again destructively interfering with the El Nino background state as the enhanced MJO phase draws closer to the Indian Ocean. This is best evidenced in the extended range ECMWF RMM forecasts, which depict a forecast evolution that well mimics the MJOs passage across the Western Hemisphere and Indian Ocean approximately 30-40 days ago. Objectively wave filtered upper-level velocity potential anomaly forecasts from the ECMWF are supportive of this realization, and depict a weakening and breakdown of a wave-1 pattern as the leading edge of the enhanced MJO envelope crosses the Prime Meridian later in July. Although the GEFS and CFS favor a much less progressive mean MJO signal that stalls in the Western Pacific, the ECMWF is preferred due to its better handling of the MJO phasing and strength during its period of destructive interference with El Nino last month. Therefore, the updated outlook relies on an MJO that becomes increasingly disorganized while continuing to propagate eastward into the Indian Ocean near the start of August. Even though the MJO looks to compete with the El Nino background state, conditions look to remain favorable for additional TC development in the Western Pacific and eastern Pacific (highest chances) during the next several weeks. Based on an uptick in climatology and forecast MJO phasing, there are better chances for TC formation in the Caribbean and tropical Atlantic compared to previous outlooks, however forecast confidence for genesis remains low due to the prevailing hostile environment in the basin mainly tied to the ongoing El Nino.
No new TCs formed during the past seven days. After weakening from Super Typhoon strength last week, TC Bavi continued to track northwestward over the Philippine and East China Seas and made landfall on 7/11. Before fully dissipating, the system brought heavy rainfall, battering winds, storm surges, and other adverse ground impacts over eastern China during the past few days. For week-1, TC activity looks quiet down at least temporarily in the western Pacific, though there are multiple areas being monitored for potential TC development by the National Hurricane Center (NHC). In the central Pacific, the NHC is monitoring a pair of lows (Invests 90C and 91C) located to south of Hawaii with 50% and 40% chances of formation, respectively, during the next week (as of 1:00pm EDT). Further east, the NHC is monitoring another pair of areas approximately between 120W and 100W with 100% (Invest 96E) and 70% chances of developing, respectively, during the seven days as well (as of 1:00pm EDT). While not currently highlighted by NHC, probabilistic tools also point to some TC potential during week-1 associated with a low forming in the eastern Gulf of America, as well as an easterly wave moving off West Africa, however this latter feature appears likely to succumb to a high shear environment in the MDR near 40W.
Based on latest model guidance, the two areas highlighted in the eastern Pacific mark the potential start of a successive series of tropical lows forming over this part of the basin in the next couple of weeks. As the MJO propagates eastward, the large-scale environment looks to become increasingly favorable for multiple TC formation, much in the same manner as the first 3 eastern Pacific TCs of the season (Amanda, Boris, Cristina) that formed during the last passage of the MJO over the basin back in early June. In addition, objective wave filtering of upper-level velocity potential anomalies shows equatorial Kelvin and Rossby wave activity intersecting the eastern Pacific to further aid in formation with very strong divergence aloft. Therefore, 60% chances for TC formation are posted for week-2 where formation is most likely based on MJO phase 1 and 2 TC genesis composites and probabilistic tools from the ECMWF and Google AI. Surrounding this high risk area, broader areas of 40% and 20% chances posted to capture any early or delayed formations. By the week-3 period, the environment looks to remain favorable for additional TC activity, with much of the enhanced trades located to the south of Mexico potentially relaxing, and allowing for formation to occur further east. 40% chances for development are posted for week-3 and are nudged slightly eastward compared to week-2. Across the central Pacific, additional TC development is also possible in the wake of Invests 90C and 91C later in July. However, probabilistic TC tools lack any coherent region of renewed genesis signals with ensemble solutions becoming quite diffuse, precluding any corresponding TC shapes in the updated outlook.
Across the western Pacific, anomalous lower-level westerlies associated with the low frequency base state are expected to persist, conducive for additional TC development throughout much of the basin. However, due to the favored competing interference between El Nino and MJO, odds for genesis are relatively lower. As a result, 20% chances are posted from the Philippine Sea eastward to approximately 155W where tools show modest chances for additional development. Likewise for week-2, a broad area of 20% chances is posted and extends eastward through 170W where lower-level westerlies are favored to be strongest near the equator and extended range solutions show low shear, and an untick in convection.
Despite the improved chances for TC development in the western Hemisphere, no TC areas are posted for the Caribbean and tropical Atlantic with much of the basin also favored to receive below-normal precipitation in the updated outlook. There continues to be modest signals in the tools to limit outlook confidence even with the more favorable MJO phasing and more active climatology. Additional easterly wave activity propagating off West Africa looks to continue, though any formation would be most likely to occur in the far eastern Main Development Region (MDR) before these waves soon become embattled by a strong shear zone extending from the Caribbean through 40W that is favored to persist through early August. Lower shear conditions are favored across the Gulf of America and subtropical Atlantic which would help provide some opportunity for TC development, though there is high difficulty in predicting these higher latitude disturbances with any reasonable skill at extended leads.
The precipitation outlook for weeks 2 and 3 is based on El Nino and Western Hemisphere MJO historical composites for June-August, and informed by a skill weighted consolidated blend of ECMWF, GEFS, and CFSv2 ensemble forecast systems to refine probabilistic coverage areas. While the Indian monsoon has reached its peak coverage in early July, below-normal precipitation is favored in the outlook tied to the strong El Nino influence of suppressed divergence aloft predominantly favored over the Indian subcontinent. Above-normal temperatures with possible extreme heat conditions are favored for parts of the southern U.S., Mexico, as well as across eastern equatorial Africa. 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 which are issued daily. Forecasts issued 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:
- 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.
|
Product Resources
|
|
Feedback and Questions
|
|
www.nws.noaa.gov
