Hurricane Earl Reaches Dangerous 'Category 4' Strength

The above is a "visible" satellite image of Hurricane Earl that was taken just as the sun was setting over the storm about 90 minutes ago.  Below is the most recent "infrared" satellite image of Earl, which is not dependent upon sunlight in order to show the system (it measures the temperature of the clouds instead, and paints the resulting picture).

As you can see, Earl has a well-defined eye, which at 6pm Central Time was centered about 95 miles Northeast of San Juan, Puerto Rico.  As of the 6pm advisory, Earl had intensified to category 4 strength, with maximum sustained winds of 135 mph.

Below is the latest WSR-88D radar image from the San Juan radar site, which again shows the well-defined eye to the Northeast of San Juan:

Earl is currently moving toward the West/Northwest at 15 mph.  This general motion is expected to continue for the next 12-24 hours, with a gradual turn toward the Northwest expected over time.

Beyond Wednesday is where the forecast becomes interesting, particularly with respect to any potential impacts on the U.S. East Coast.  Below is the latest composite map showing the forecast tracks depicted by the major computer forecast models.

The important thing to remember when looking at either the National Hurricane  Center forecast track map (next to last image above) or the computer forecast model composite map (image above) is that Earl is larger than just one central point, (which is what these maps are tracking).  As of this writing, Tropical Storm Force winds extended outward up to 200 miles from the center, and Hurricane Force winds extended outward up to 70 miles from the center.  With this in mind, you can see how the center of Earl could pass well East of, say, the North Carolina coast, while dangerous winds and storm conditions could still affect the coastline and points inland.

The critical feature in determining Earl's potential impact on the U.S. appears to be the development of a trough of low pressure across the Great Lakes region by mid to late week.  If this feature develops and moves East rapidly, it will force Earl back out to sea.  On the other hand, if it develops more slowly and/or is further West from Earl than currently expected, Earl could move closer to the U.S. coastline (or potentially inland) before being turned back out toward the East.  

Residents all along the East Coast of the U.S., and particularly from the Carolina's Northward through New England, should maintain a close watch on Earl over the coming days and watch for updated forecasts & warnings.