The Atlantic heats up… West Pacific stays active


As August commenced, the Atlantic’s tropics turned on. There are three systems out there to track. Meanwhile, the Western Pacific remains active – it is the most active basin in the world and seems to be catching up for a couple of inactive seasons.

Tropical Storm Ernesto: Tropical Storm conditions were observed in the Windward islands with sustained winds reaching 41mph gusting to 63mph on St. Lucia, and sustained at 43mph on Barbados. Rainfall totals between two and five inches are forecast for the Windward Islands. The storm is currently in the Eastern Caribbean with 50mph winds and a minimum central pressure of 1002mb. Although dry air evident by surface outflow boundaries from collapsing thunderstorms and a high forward speed are currently keeping Ernesto from organizing and strengthening, the National Hurricane Center expects Ernesto to continue west and west-northwestward into the western Caribbean where it should slow down and the atmospheric conditions should be substantially more favorable and allow for significant intensification into a hurricane. Interests in Jamaica, the Cayman Islands, Cuba, and the Yucatan Peninsula need to keep an eye out as they could be dealing with a hurricane in 3-5 days.

Invest 90L: A tropical wave that came off of Africa quickly organized over the Eastern Atlantic and brought gusty winds and showers to the Cape Verde islands. Currently, it is heading westward into the central Atlantic where it will have to contend with the dry stable air associated with the Saharan Air Layer, and marginally favorable sea surface temperatures. Some wind shear may also hinder development in the next few days. However, it currently has a well defined low level circulation and could already be a tropical depression – signalling the start of the Cape Verde season, where African easterly waves develop out in the central and eastern Atlantic and track westwards, these storms can become monsters as they have so long out over the water to develop.

Invest 91L: Closer to home, a tropical wave that was previously affecting the Greater Antilles Islands with scattered showers and thunderstorms has moved into the Bahamas and has spread showers towards south Florida. It is currently very disorganized, and is contending with moderate wind shear, and a small amount of dry air. The wind shear is expected to back off in the next day or two which, combined with its slow motion over the gulf stream, could allow for some development. It is forecast to slowly move north-northwestwards along the westernmost edge of the Bermuda-Azores ridge of high pressure, and could move inland over Florida at some point, its currently only has 30mph winds associated with it and heavy rain would be the biggest threat for now. The National Hurricane center gives it a 20% chance of developing in 48hours as of 8pm August 3rd.

Chinese Weather Service Radar of Typhoon Damrey August 2nd 2012

Post-Tropical Storm Damrey: Typhoon Damrey made a landfall in Northeastern China with 80mph winds on the 2nd of August. It likely produced a storm surge of nearly 5 feet with large wave on top of it, the shape of the coast line funneling water inland. Thousands of homes were damaged or destroyed in this typhoon’s path. Two deaths are attributed to the storm and damage to China will likely top in the millions of dollars. It was the most intense storm to hit China north of the Yangtze river since 1949 according to the Chinese weather service. It briefly took on annular characteristics over the Yellow sea which may have allowed it to maintain its strength despite some southerly wind shear from the upper level outflow of Typhoon Saola to it south, and the cooler shallower waters of the Yellow and Bohai seas. Damrey has since weakened to a depression and lost tropical characteristics after adding heavy rains to an area of China that has seen flooding in recent weeks.

Taiwan’s Central Weather Bureau Radar image of Typhoon Saola as a category two equivalent typhoon on August 1st 2012.

Tropical Depression Saola: Typhoon Saola made an unexpected turn to the west at the last minute with its eyewall pushing ashore in Taiwan, typhoon strength wind gusts were reported in this area of eastern Taiwan. The mountains of Taiwan squeezed out moisture from the Typhoon with rainfall storm totals in some areas approaching 6 feet making it one of the wettest tropical cyclones in Taiwan and in the world! This is after it caused substantial flooding in the Philippines. Saola weakened to a tropical storm, did a loop and went through northeastern Taiwan before making a second landfall in China with 50-60mph winds. It continues westward – inland – and should dissipate in the next day or two, not before producing heavy rain possibly triggering more flooding. At least forty people were left dead by Saola, and economic losses will likely top in the hundreds of millions of dollars. Typhoons Saola and Damrey made landfall in China within 24 hours of each other – very noteworthy.

Tropical Depression Haikui: From the region of troughiness that Typhoons Saola and Damrey left behind over the Western Pacific, Tropical Depression Haikui organized. However, as far as tropical cyclones go, Haikui is very disorganized with multiple vortices swirling around a common center. It has one poorly defined band of convection that may try to become the dominant low level circulation. However, once its circulation becomes more well defined, it will likely be in a very favorable environment and the global forecast models are showing Haikui becoming a serious typhoon. Its track, once it reaches the central islands of Japan as a strengthening tropical storm in four days, is very uncertain as a trough tries to pick it up and re-curve it northeastward. The strength and timing of this trough and of Haikui is up for grabs.Eastern Asia, from Taiwan to Japan – including China and the Korean peninsula, needs to keep a close eye on this storm.

Invest 90W: Meanwhile, as if the tropics weren’t active enough, another disturbance in the west Pacific bears watching for future development. It is currently looking  pretty extra-tropical with frontal boundaries on both sides. It does look to be in a favorable position to transition into a sub-tropical or tropical storm in the next few days. This disturbance, regardless of development is forecast to re-curve out to sea with Haikui, and since that scenario is dubious, 90W should be watched closely as well.

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