Fierce tropical cyclones occur in India during what may be called the premonsoon, early monsoon, or postmonsoon periods.
Some doubt exists as to whether the present event is actually driven by the tropics, as it aligns well with the response to an extratropical wave train extending across the Pacific and North America. Substantial convergence from both hemispheres is apparent in the far East Pacific, helping result in robust westerly anomalies at hPa.
Further, typical extratropical circulation responses to the MJO in Phase 8 do not appear to be present, giving further support to the extratropics driving the tropics in the present scenario.
Nevertheless, model guidance propagates the intraseasonal signal eastward during the next two weeks with Phase 1 conditions anticipated during Week-1, and a mix of Phase 1 and Phase 2 during Week Model guidance does show some signs of crashing the intraseasonal signal back into the unit circle late in Week However, some caution should be exercised with this solution given the developing El Nino conditions in the Central Pacific that can manifest in a shift in the mean RMM space towards the top left quadrant Phase 7 and 8.
Also of note this week, is the continuation of the westerly wind burst event near E and corresponding oceanic Kelvin wave likely acting to help reinforce the transition towards El Nino during boreal winter. Three tropical cyclones TCs developed the past week, including two Category 5 systems.
Kong-Rey underwent a prolonged period of rapid intensification from the 30th through 2nd, where it strengthened from 60 to knots as it tracked to the west-northwest. Hurricane Walaka formed south of Hawaii on the 29th of September, and intensified to a kt Category 5 system by the 1st of October.
Walaka is forecast to pass west of Hawaii, with minimal impacts to the islands. Lastly, Hurricane Sergio formed off the southern coast of Mexico on the 29th, with a more modest peak intensity of 85 knots thus far.
Sergio is forecast to continue intensifying while tracking west-northwestward into Pacific, but shows signs of possibly recurving and approaching the northern Baja Peninsula during the second half of Week This system could bring another shot of heavy rainfall into the Southwest.
Multiple areas are being monitored for TC formation potential during the next two weeks. The National Hurricane Center NHC is monitoring a broad area of low pressure in the southwestern Caribbean that may become increasingly organized while tracking northward in the coming days with forecasts showing weakening of ongoing westerly wind shear.
This system could bring heavy rains to the southeastern U. In the East Pacific during Week-2, moderate confidence of a TC developing exists between roughly W and N due to persistent conditions favorable for TC formation and easterly shear forecast over the region.
High confidence exists for the northern hemisphere system to develop off the southwestern coast of India, with a track towards Oman.
Precipitation forecasts during the next two weeks are closely tied to the ongoing and forecast TC activity. As the MJO pushes towards the Indian Ocean, conditions in that basin are anticipated to shift towards favoring above-normal precipitation, with increased suppression of convection across the West and Central Pacific as the suppressed phase of the MJO transitions towards that region.
During Week-2, the low frequency state and suppressed phase of an equatorial Rossby wave are anticipated to destructively interfere with the MJO-favored enhanced convection across the Indian Ocean, leading to reduced forecast confidence across the region.
High confidence also exists for below-normal temperatures across much of the western U. Despite this, the MJO in Phase 1 is typically associated with deepening trough over the West, but the upstream circulation pattern from empirical guidance during Phase 1 looks nothing like the observed circulation.
Forecasts over Africa are made in consultation with the CPC international desk, and can represent local-scale conditions in addition to global-scale variability. 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 and soon will be recorded. The update only spans the release period from June 1 through November 30 and a region from E to the Prime Meridian in longitude and from the equator to 40N in latitude.
The update does not extend the time horizon of the product, but rather applies for the remaining 4 days of the previous Week-1 time period and Days 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.
Product Description The Global Tropics Hazards and Benefits Outlook is a forecast for areas with elevated odds for above- or below-median rainfall, above- or below-normal temperatures and regions where tropical cyclogenesis is favored 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.
Above below normal temperature forecast areas are depicted in orange and below 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.
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.
Product Forecast Tools The outlook maps are currently created subjectively based on a number of forecast tools, many of which are objective.These include 10 landfalling tropical cyclones in Japan in , five tropical cyclones affecting the Cook Islands in a five-week period in , Cyclone Gafilo in Madagascar in , Cyclone.
Tropical cyclone: Tropical cyclone, an intense circular storm that originates over warm tropical oceans and is characterized by low atmospheric pressure, high winds, and heavy rain. Also called typhoons and hurricanes, cyclones strike regions as far apart as the Gulf Coast of North America, northwestern Australia, and eastern India.
The southwest Indian Ocean cyclone season started on November 15, and will officially end on April 30, A tropical cyclone called Fakir formed on April 23 near northeastern Madagascar. The modelling is conflicting, but the Bureau of Meteorology says one, possibly even two cyclones could form off the Queensland coast by the end of this week.
A new paper suggests there is an “unprecedentedly” low number of tropical cyclones around Australia at the moment. (How much should we spend to avoid this dreadful outcome I wonder?) I am a little skeptical of how we can be so sure of the cyclone activity in, say, the year AD.
But. Tropical cyclones in the Australian region are influenced by a number of factors, and in particular variations in the El Niño – Southern Oscillation. In general, more tropical cyclones cross the coast during La Niña years, and fewer during El Niño years.
Analysis of historical tropical cyclone.