Alex is gone; the tropics are relatively quiet

Hurricane Alex is gone, killed by the high mountains of northern Mexico. Alex's rains linger on, and will continue to cause flooding problems in northern Mexico today. Alex killed at least 24 people in its week-long traverse of the Caribbean and Gulf of Mexico. One death occurred in the Dominican Republic, and fourteen were killed in Central America. In Mexico, the outer rainbands of the storm killed three in Acapulco, one person in Oaxaca, and one person in Chiapas. Following its final landfall, Alex caused at least eight deaths in Nuevo León, with three persons reported missing. It is possible Alex will have its named retired, though I think it unlikely. One of the countries substantially affected by a hurricane must make a request to the World Meteorological Organization (WMO) to have the hurricane's name required. Mexico was the country most affected by Alex, and Mexico has been reluctant to make retirement requests in the past. For example, Mexico suffered two landfalls from Category 5 Hurricane Emily in 2005, yet did not request that Emily's name be retired; there will be a new storm named Emily next year.

I hope Alex will give the officials in charge of the BP oil disaster a bit of a wake up call. We've been told that five days are required to shut down operations in the event of tropical storm force winds are forecast for the clean-up region. It is very unrealistic to expect a five day warning, since the average track error in a 5-day forecast is about 300 miles. Furthermore, we have little skill forecasting the formation of tropical storms, and it is often the case that a tropical storm forms just a 1-day journey from the Deepwater Horizon blowout location. If we examine the incidence of tropical storm force winds in that region over the past five years, I suspect that they were successfully predicted five days in advance perhaps 30% of the time.


Figure 1. Microwave satellite image of Alex at landfall. Image credit: Navy Research Lab.

The tropics are relatively quiet
A cold front that pushed off the Southeastern U.S. and Gulf Coast has stalled out over the waters immediately offshore. Some of the models give support for an area of weak low pressure to develop over the northern Gulf of Mexico along this front. NHC is giving a 10% chance of a tropical depression forming by 8am Sunday over the northern Gulf of Mexico. The GFS model is also indicating development may occur by the middle of next week along the portion of the front offshore from South Carolina. There is also some suggestion by several models that a strong tropical disturbance may form by the middle of next week in the Gulf of Mexico's Bay of Campeche, or in the Western Caribbean. At this point, none of these possibilities are worthy of significant concern, though we'll keep to keep an eye on them.

I'll have an update Saturday afternoon. Have a great holiday weekend, everyone!

Jeff Masters