|
Weeks 2-3 Global Tropics Hazards Outlook (GTH)
|
|
Outlook Map and Data
|
Last Updated -
06/06/23
|
|
|
|
|
|
Outlook Discussion
|
Last Updated -
06/06/23
|
Valid -
06/14/23 - 06/27/23
|
Since late May, the enhanced phase of the Madden-Julian Oscillation (MJO) has propagated from the western Pacific and into the Western Hemisphere where it has gradually decreased in amplitude in RMM space. The loss of strength is generally consistent with recent upper-level velocity potential anomaly observations, and appears to be tied to destructively interfering modes of variability in the tropics. Despite this, the leading edge of the convective envelope has shifted well beyond the Prime Meridian, and there is good agreement in the RMM forecasts favoring continued eastward propagation of the MJO at low amplitude over the Indian Ocean during week-1, followed by an uptick in amplitude over the Maritime Continent during week-2. Beyond mid-June, ensemble spread greatly increases in the RMM forecasts, however these predictions have trended in favor of a more coherent MJO at this lead, with several ensemble members depicting a potentially fairly robust event unfolding over the western Pacific during the week-3 time frame. Given support for the continuation of well-organized intraseasonal activity in the upper-level velocity potential forecasts, the outlook relies on this perspective, resulting in increased chances for tropical cyclone (TC) development being favored over the Western Pacific during the period. With the suppressed phase of the MJO expected to shift across the Western Hemisphere, the large-scale environment is expected to become less conducive for TC development over the Eastern Pacific and Atlantic basins, however tropical cyclogenesis cannot be ruled out given an increasingly active climatology later in June.
During the past week, three TCs developed in the global tropics. In the Atlantic basin, TC Arlene developed on 6/1 and briefly peaked at tropical storm intensity in the Gulf of Mexico before dissipating over open waters this past weekend. Within the last several hours, a pair of TCs formed in the northern Indian Ocean (02A) and the western Pacific (TS03W). With its formation likely tied to the recent passage of a Kelvin wave in the Arabian Sea, 02A has rapidly consolidated and the Joint Typhoon Warning Center (JTWC) expects this system to gradually intensify under a favorable shearing environment, tracking northward during the next several days. Later in week-1, deterministic solutions show the system generally weakening likely due to dry air entrainment, but are divided in regards to its eventual track, with the GFS (ECMWF) favoring a more westerly (easterly) solution over the northern Arabian Sea. Regardless of its track, enhanced precipitation amounts are favored late in week-1 and into early week-2. In the Philippine Sea, TS03W is forecast to reach category two intensity while tracking poleward during the next several days. Thereafter, model guidance shows this system recurving along the western periphery of a subtropical ridge but could bring potentially heavy precipitation amounts to portions of southern Japan. For the latest information regarding these two active systems, please refer to updates from the JTWC.
In the Western Pacific, additional TC formation remains favored over the South China Sea tied to strengthening low-level westerly anomalies and predicted Rossby wave activity. Probabilistic tools and ensemble guidance suggest formation is more likely late in week-1, however 20% chances for TC development are issued should any potential development be delayed in the region. To the east, 40% chances for TC development are issued for week-2 over the Philippine Sea where there is increased support in the GEFS and ECMWF ensembles for an area of deepening low pressure and more elevated signals in latest probabilistic tools. Accompanying this area, 20% chances for TC development is posted extending eastward beyond the Mariana Islands given a broad area decreasing shear favored in the dynamical models and another area of low pressure which may form to the south of Guam.
The enhanced phase of the MJO also supports potential TC development in the Bay of Bengal which is reflected in latest probabilistic guidance, however no shapes are posted due to increased shearing associated with the predicted onset of the Indian monsoon and an overall decrease in activity in the TC climatology by mid-June. Likewise across the eastern Pacific and Atlantic, no TC areas are issued for week-2, given the development of anomalous lower-level easterlies and the building of a subtropical ridge over Mexico resulting in drier than normal precipitation forecast.
The precipitation outlook for weeks 2 and 3 is based on a historical skill weighted blend of GEFS, ECMWF, CFS and Canadian ensemble guidance, anticipated TC tracks, and historical precipitation composites of Maritime Continent and Western Pacific MJO events during May-Jul. For temperatures, a sluggish or dry start to the Indian monsoon favors above-normal temperatures for portions of India, and the aforementioned development of subtropical ridging over North America is also expected to increase the risk of much above-normal temperatures for parts of Mexico and the south-central U.S. Calibrated reforecast tools indicate increased chances for daytime temperatures exceeding 100 degrees F across parts of southern Texas and northern Mexico during the week-2 period.
For hazardous weather concerns in your area in the coming 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 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 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 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
