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Tropical Storm Emily stalls, remains a threat to Hispaniola

By: Dr. Jeff Masters, 12:37 AM GMT on August 04, 2011

All afternoon, Tropical Storm Emily has remained on a westward track with maximum sustained winds of 50 mph. In the 8pm EDT update from the National Hurricane Center, the storm was nearly stationary, with no forward movement. The storm gained some thunderstorm activity over its center of circulation throughout the day, but remains sheared to the east. In order for tropical cyclones to intensify (or, continue to exist at all), they need to be vertically stacked and standing straight up in the atmosphere. Emily continues to be tilted east due to 20 knots of westerly wind shear, which is apparent on satellite and also in recent satellite analysis of upper-level circulation.

Emily's tropical storm-force winds extend 115 miles to the north and east of the center, and tropical storm conditions are probably already being felt in Hispaniola. Isolated rainfall amounts of up to 20 inches are expected on the eastern side of the storm. The longer Emily tracks west before making a turn to the northwest, the more likely it is that Haiti will see the heavier rainfall amounts. In any case, Emily is a serious threat for flash flooding and mudslides on the island of Hispaniola and eastern Cuba.

Figure 1. MODIS satellite imagery from earlier today, plotted using NASA's new Rapid Response Web Mapping Service.

Forecast for Tropical Storm Emily
The forecast for Emily remains similar to this morning's update, with a slight shift to the east in track. The National Hurricane Center forecasts that the storm will make landfall in Haiti overnight tonight or early tomorrow as a tropical storm. After that, it will continue on a track to the northwest until Saturday, when it will turn to the northeast and out to sea. This is all assuming Emily makes the turn to the northwest over the next 12 hours.

This afternoon the HWRF and GFDL shifted their forecast track slightly to the east away from the Florida coast. Consensus shifted this way as well, and that change is also present in the official forecast track. As the storm moves north of Hispaniola and Cuba, environmental conditions will become more favorable, and the storm could gain some organization. But this is very hard to predict since Emily hasn't actually made a turn to the northwest, yet. Furthermore, the longer Emily tracks to the west, the more of a threat it becomes to the Florida coast.

Typhoon Muifa a landfall threat for China coast

Typhoon Muifa has sustained winds of 109 mph, with gusts up to 132 mph, and is a category 2 on the Saffir-Simpson Hurricane Scale. Muifa's concentric eyewalls are plainly visible on both infrared satellite imagery as well as radar, which is indicative of a mature, intense cyclone undergoing eyewall replacement cycles. Typhoon Muifa is expected to remain a category 2 with winds of at least 104 mph through mid-day Saturday, at which point it is forecast to intensify slightly to a category 3 as it approaches the China coast. As of this afternoon, Muifa is expected to make landfall south of Shanghai, near Zhoushan, Saturday afternoon or evening (local time). In addition to being a serious threat to all of the involved coastal cities, this is a particularly dangerous track for Shanghai and Hangzhou, since near-hurricane-strength winds will be out of the east, pushing water into the surrounding inlets. The forecast landfall location has been trending south along the coast, so it doesn't appear that China will be able to escape a Muifa landfall.

Figure 2. Infrared satellite imagery of Typhoon Muifa from August 3rd.

Dr. Carver will have an update later tonight should there be any interesting changes to Emily or the forecast. I'll be back tomorrow with another post.



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