The National Hurricane Center has been advertising Hurricane Earl’s maturation for several days. And now, it appears that Earl is on the verge of becoming the season’s second major (Category 3) hurricane. A Category 3 storm (on the Saffir-Simpson Hurricane Scale) means that sustained hurricane winds have reached 111 mph or more.
The good news is that upper level steering currents are evolving (Fig. 1) in such a way that Earl will be steered toward the northwest and then recurve to the northeast, only skirting the U.S. East Coast (Fig. 2). Still, some parts of the Atlantic Seaboard remain within the infamous “cone of uncertainty.”
This “cone” is rather narrow this time because most computer models are tracking Earl in similar fashion (Fig 3). Still, according to NHC forecasters, the average error in NHC position forecasts for days four and five is 200 and 300 miles, respectively. Hence, “…It is too soon to determine what…if any…parts of the U.S. East Coast might see direct impacts from Earl later this week.”
Regardless of whether Earl strikes the East Coast, high waves will surely continue to affect the region. Already rough seas, high tides and waves from Danielle have wreaked havoc to seaside resort areas. Hundreds of rescues from rough surf and rip currents were reported during the past three days. One person died in Florida while swimming at beach without lifeguard protection.
Although Danielle was far out to sea, about 1,000 miles at its closest position to the U.S., (Fig. 4) her spiraling wind pattern sent out swells in all directions. As those swells reached the U.S. East Coast, they transformed into waves. The strength and frequency of these, coupled with their interaction with near-shore sand bars, created or enhanced breaks in the sand bars. These breaks allowed for the development of channels of fast moving currents, as beached waters raced back to sea.
With seas already rough, and with Earl expected to pass much closer to the U.S. than did Danielle (center less than 200 miles to Cape Hatteras early on September 3rd), look for continued and enhanced wave action along the East Coast the next five days. Here in southwest Florida, the Florida peninsula itself will protect us from any of the Atlantic wave action. Other than continued heat and humidity (with some scattered afternoon thunderstorms), it’s not a bad time to visit the beaches. In fact, my wife and I walked the Naples beaches yesterday and really enjoyed the calmness and clearness of the waters.
If you want to experience this swell generation effect, just fill a large mixing bowl with water (this is the ocean basin). Now rapidly stir the water in a large counter-clockwise spiral (that’s the hurricane). Watch how the water splashes along the edges of the bowl (coastal interactions). Finally clean up the water that has splashed everywhere!
Meanwhile, Fiona looms further out in the Atlantic and could be a player as we enter the Labor Day weekend. Right now computer models take what will be Fiona toward Bermuda (Fig. 5). Danielle passed east of Bermuda and Earl should head to its west. With the Atlantic pattern basically stuck in a rut (with recurvature taking place throughout the western Atlantic), Bermuda can’t escape forever.
Stay tuned!
© 2010, H. Michael Mogil
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