Topsail beach, NC 11am Loudspeakers from a beach patrol truck blaring the warning "Hurricane Earl has generated strong waves and rip currents..." greeted me as I walked towards the water fins in hand. Long lines, the sign of a long period swell produced by a large distant storm, marched towards the beach like marines in parade.
Tomorrow the battle will begin.
Today's latest track model runs bring Earl perilously close to Cape Hatteras and Cape Cod. The Navy's NOGAPS model, which has been often running west of the other models brings Earl over Cape Hatteras and Cape Cod. Because the NOGAPS model has tended to have a pretty consistent bias this hurricane season, the model consensus is still that Earl stays offshore until it landfalls in Canada. However, the NOGAPS track is within the margin of error of the NHC track.
The Navy model forecast would bring high winds, huge surf and a massive storm surge to Okracoke and Hatteras Islands, which have begun to be evacuated.
After striking Cape Hatteras, Earl would track towards Cape Cod bringing damaging surf and a large storm surge to Long Island and Cape Cod, according to the NOGAPS forecast.
The leading north-easterly edge of Earl will have a long fetch developing huge waves as it moves towards Cape Cod.
Both Long Island and Cape Cod could suffer massive beach erosion and property loss if the NOGAPS model validates.
Even if Earl stays offshore, following the consensus track, waves will be massive and damaging because Earl is a large, strong storm. The East Bahamas weather buoy registered 48.6 foot high waves when Earl passed over it.
Earl will be fueled by exceptionally warm water until it passes north of the Gulf Stream.
Wind shear and dry air have kept Earl from becoming a category 5 hurricane, which could be supported by the high water temperatures. Earl strengthened back to a category 4 hurricane when the wind shear backed off. Water temperatures don't cool significantly until north of Cape Hatteras.
Storms moving north rapidly may occasionally exceed the maximum potential intensity. That's why Long Island and Cape Cod could be hit by hurricane force winds.
Jeff Masters notes that Earl is a large storm that could generate a large storm surge.
Earl is a large hurricane, which gives it a higher potential for storm surge damage than a smaller hurricane with the same top winds. One measure of a storm's power, useful for gauging storm surge threat, is to measure the speed of the winds and multiply by the area over which those winds blow. This total is called the Integrated Kinetic Energy (IKE). Based on the storm's IKE, one can come up with a scale from 0 - 6 rating the storm's destructive power from its storm surge. A separate rating can be given to the destructive potential of the storm's winds. The IKE value of 112 Terrajoules for Earl, at 3:30pm EDT today, gives its storm surge a destructive power of 5.0 on a scale of 0 - 6. Earl's winds have a lower destructive power, 3.4 on a scale of 0 - 6. Let's hope the right front quadrant of Earl, where the main storm surge would occur, stays offshore! For comparison, the small Category 5 Hurricane Camille of 1969 had an IKE of 80 Terrajoules, and the very large Category 2 Hurricane Ike of 2008 had an IKE of 116 Terrajoules--similar to Category 3 Earl's.
The latest infrared image of Earl shows improving symmetry and stronger convection than earlier in the day. Earl is strengthening.