During the past 24 hours, Isabel has encountered fairly significant vertical wind shear, on the order of 20kts from the southwest. This is very evident in satellite imagery. SSTs under the storm continue to be plenty warm at about 29C, but her slow forward motion could be responsible for some degree of upwelling. She's also been ingesting some drier air from the western side which has snuffed convection out a bit. At 15Z today, Hurricane Isabel was located at 27.4N 71.2W and tracking NNW at 7kts. Intensity has dropped quite a bit to 90kts and 959mb, making her a CAT2 storm. That is still a strong hurricane, but there's the possibility that she COULD reintensify before landfall if the shear lets up at all. The hurricane-force winds extend 80 miles on the northwest quadrant, so the exact location of where the eyewall makes landfall is not so important; it's a large storm. A Hurricane Watch has been issued for a large stretch of the Atlantic seaboard, from Little River Inlet, SC to Chincoteague, VA. These watches will probably be upgraded to warnings at the 21Z advisory today or 03Z tomorrow. Precautions are already being completed, such as moving ships out to sea to avoid being battered at port, coastal evacuations, inland shelters being established and manned, and positioning of emergency managers, utility repair workers, and Red Cross personnel. It's likely that many more evacuations will be made mandatory by Wednesday morning. Although Isabel has weakened a bit recently, she still poses a very significant threat, in terms of winds, storm surge, high surf, and rainfall. NHC's forecast places landfall near Cape Lookout, NC on Thursday mid-morning, then tracking inland over central VA and PA. The passage over VA is expected early Friday morning, and then midday Friday for PA.
Please visit my tropical Atlantic headquarters.
P.S. The aircraft reconaissance data that we enjoy so much is something we shouldn't take for granted. First of all, the Atlantic basin is the only one in the world with routine recon flights, thanks to both NOAA and the US Air Force. And this past Sunday, for the first time since 1989, there was a close call which thankfully didn't result in an accident. As Pete Black of the NHC describes, "While climbing back to altitude on Sunday after the second stepped descent, less than a minute after the 200 ft run, the inboard engine on the right side flamed out with two small exhaust explosions, and had to be shut down. Thank God the aircraft was back to 1500 ft at the time and that it was late in the flight, as the aircraft was able to continue climbing to safe altitude and return to St Croix, where they were greeted by the airport fire department lining the field after the aircraft commander declared an emergency." The plane and all crew returned safely, but not without a bit of a scare.