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Posted at 11:30 AM ET, 06/28/2010

Alex in the Gulf - oil interactions uncertain

* Heat today, then relief: Full Forecast | Hurricane Tracking Center *


The most recent measurements noted by the National Hurricane Center (NHC) indicate that Alex remains at tropical-storm strength with 60 mph winds, 989 mb pressure, and a center fix about 535 miles southeast of Brownsville, Texas. Alex is a large tropical cyclone with an impressive satellite presentation. In the image above, the inner swirl of Alex is at the far southwestern corner of the Gulf of Mexico while the outflow cirrus cloud bands extend all the way to North Florida.

The track guidance generally suggests Alex will move toward the northern Mexico Coast in the coming days -but perilously close to Texas. NHC's official forecast has the center of circulation moving onshore roughly 50 miles south of the border.

Given these track projections, interaction with the Gulf oil spill will be reduced, and the U.S. Gulf coast will most likely be spared the worst. But a stiff east or southeast wind across the northeast Gulf might push "weathered" (non-flammable) oil onshore toward the northwest -- towards the Louisiana, Mississippi and Alabama coast. The specific interactions and impacts are difficult to predict, however.

Keep reading for more on Alex...

Because Alex is so large, even with a Mexico landfall, a significant concern still exists with the potential for flooding rains along the northern Gulf Coast by the end of this week. The large outer swirl associated with the cyclone will draw very moist tropical air northward atop a nearly stationary front that has recently settled near the coast. And of course, as the uncertainty diminishes in the next couple of days regarding Alex's future, we will be able to more clearly discern who gets the rain and wind and who doesn't.

In terms of Alex's intensity, fortunately, much of the coherency its youthful inner core once possessed was unraveled by its transit over the southern Yucatan Peninsula on Sunday. This encounter with land, in my opinion, has thus far prevented explosive development. Had Alex bypassed the Yucatan and remained over water, it may very well have developed an inner structure highly suited to intensify rapidly, given the high heat content of the ocean environment at that latitude, and the nearly ideal wind conditions that recently surrounded the circulation.

The expanse of its near galaxy-like symmetry is clearly on display in the observations of the southwestern Caribbean atmosphere.

Alex's circulation extends outward so far it's almost as if the tropical cyclone itself defines the flow characteristics over that part of the globe, rather than just simply being a small part of an otherwise dominant ambient wind regime. Prior to its encounter with the Yucatan, its satellite presentation reminded me of the tropical cyclones we sometimes see in the western Pacific Ocean, where the cyclone stands alone in an environment nearly impervious to the destructive influence of the traveling troughs and ridges in the westerlies.

Fortunately, we are not dealing with a situation like that. In fact, we are already seeing the encroachment of nontropical flow into the northwestern Gulf of Mexico. High-altitude westerly winds in this region are beginning to restrict Alex's outflow in its northwest quadrant, elongating the upper-most part of its circulation in a southwest-to-northeast direction.

In addition, a strong trough is forecast to progress through the eastern half of the country early this week and penetrate far enough southward to interfere with Alex's intensity and track. Though forecast to reach hurricane status by tomorrow, I am hopeful Alex will be disabled enough via its proximity to Mainland Mexico and its interaction with the continental weather systems that it will never mature beyond minimal hurricane strength. We shall see.

By  |  11:30 AM ET, 06/28/2010

Categories:  Tropical Weather

 
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