Monday, July 18, 2011

A tropical storm, but no threat

We talked last week about the possibility of a tropical system forming off the South Carolina coast on Sunday and Monday, and the computer models had the right idea.

Tropical Storm Bret is about 100 to 150 miles south of where the computers predicted it might be, but it's roughly in the ballpark.

Meteorologists can't see any way this storm will affect the Carolinas directly, although vacationers on the Outer Banks might see rougher surf and possibly rip currents Wednesday, when Bret is moving to the northeast, several hundred miles offshore.

Bret isn't even forecast to become a hurricane, with most predictions call for it strengthening to a 60-mph tropical storm as it zooms to the northeast, into the open Atlantic Ocean. Eventually, wind shear (a strong counter-clockwise flow around low pressure in the Northeast) will weaken Bret.

Once again, however, we see the same pattern affecting the Carolinas.

High pressure is centered in the Atlantic, and another high is over the Midwest. For several weeks, the Carolinas frequently have been in the middle, between these two highs. Occasionally, the Midwest high pushes eastward a bit and brings higher temperatures (upper 90s). Then it moves back to the west a bit, and the Carolinas get into the flow of low pressure systems moving clockwise around the edge of the high's circulation area.

What happens in another month or two, when tropical storms and hurricanes approach the Southeast coast? Where will the high pressure systems be, and where will the channel between those two highs be set up?

Will the circulation around the Atlantic high serve to steer systems toward the Southeast? Or will tropical storms and hurricanes be recurved back out to sea as they approach the U.S. coast?

If the current pattern persists into August and September -- and weather patterns often persist -- there could be a lot of nail-biting this hurricane season along the coast.