Isabel
(1) Isabel is 515 km ENE of the Turks and Caicos Islands with winds of 155 mph (933 mb minimum central pressure). That pressure has come down somewhat in the last twelve hours, although it is slightly higher than the pressure recorded this time yesterday. Despite having an eye of 40 NM diameter, Isabel maintains its strength and should continue at high Category 4 / low Category 5 strength for approximately sixty hours, as it moves into warm water and stays in a low shear environment. After that, Isabel is due for a critical sixty hour period in which it will strike its initial blow against the East Coast. During this period, it will experience somewhat more shear and cooler waters, but if its eye narrows, it could maintain strength. At this point, I think that its large eye may explain how it is maintained its strength for so long, since it provides a very large area for the hurricane to draw energy from the warm water.
(2) and (3) At the moment, two main solutions have been proposed by the models. These solutions are very similar, and their differences are chiefly based on accounting for the strength of the wind field beyond the western continental shelf of the North Atlantic Ocean and the estimated strength of upper level high pressure over the Eastern United States in roughly 96 hours. Both solutions take Isabel off Cape Hatteras by about noon EDT Thursday. At roughly that juncture, there is divergence. The National Hurricane Center favors the southern solution, which takes Isabel along the Outer Banks and the Virginia Capes into the Chesapeake Bay. Landfall (in the sense that the hurricane will have nowhere to go but land after that point) then occurs at the start of Friday morning somewhere near Baltimore, MD (perhaps further south, maybe at Arden on the Severn). The National Hurricane Center does not specify intensity at that particular time, but provided that most of its center remains over Chesapeake Bay (which has been experiencing high water temperatures this summer, if I recall rightly), Isabel could be a middling Category 2 hurricane at landfall. By Friday afternoon, Tropical Depression Isabel will be over a cooler body of water, nanely Lake Ontario.
I favor the northern solution (which depends on a stronger upper high pressure system). After Hatteras, the storm moves towards the Delmarva, making landfall near Exmore or Onancock with winds of 105-110 mph (minimum central pressure 961 mb). This should occur about 10 PM Thursday. After that point, Isabel moves nearly north to south through Delaware and then between Chester and Philadelphia towards the Lehigh Valley. Twelve hours later, it should be not too far south of Albany.
ESA(20030914.1)
(1) Isabel is 515 km ENE of the Turks and Caicos Islands with winds of 155 mph (933 mb minimum central pressure). That pressure has come down somewhat in the last twelve hours, although it is slightly higher than the pressure recorded this time yesterday. Despite having an eye of 40 NM diameter, Isabel maintains its strength and should continue at high Category 4 / low Category 5 strength for approximately sixty hours, as it moves into warm water and stays in a low shear environment. After that, Isabel is due for a critical sixty hour period in which it will strike its initial blow against the East Coast. During this period, it will experience somewhat more shear and cooler waters, but if its eye narrows, it could maintain strength. At this point, I think that its large eye may explain how it is maintained its strength for so long, since it provides a very large area for the hurricane to draw energy from the warm water.
(2) and (3) At the moment, two main solutions have been proposed by the models. These solutions are very similar, and their differences are chiefly based on accounting for the strength of the wind field beyond the western continental shelf of the North Atlantic Ocean and the estimated strength of upper level high pressure over the Eastern United States in roughly 96 hours. Both solutions take Isabel off Cape Hatteras by about noon EDT Thursday. At roughly that juncture, there is divergence. The National Hurricane Center favors the southern solution, which takes Isabel along the Outer Banks and the Virginia Capes into the Chesapeake Bay. Landfall (in the sense that the hurricane will have nowhere to go but land after that point) then occurs at the start of Friday morning somewhere near Baltimore, MD (perhaps further south, maybe at Arden on the Severn). The National Hurricane Center does not specify intensity at that particular time, but provided that most of its center remains over Chesapeake Bay (which has been experiencing high water temperatures this summer, if I recall rightly), Isabel could be a middling Category 2 hurricane at landfall. By Friday afternoon, Tropical Depression Isabel will be over a cooler body of water, nanely Lake Ontario.
I favor the northern solution (which depends on a stronger upper high pressure system). After Hatteras, the storm moves towards the Delmarva, making landfall near Exmore or Onancock with winds of 105-110 mph (minimum central pressure 961 mb). This should occur about 10 PM Thursday. After that point, Isabel moves nearly north to south through Delaware and then between Chester and Philadelphia towards the Lehigh Valley. Twelve hours later, it should be not too far south of Albany.
ESA(20030914.1)
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