Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.
By: Dr. Jeff Masters , 3:35 PM GMT on September 11, 2005
Ophelia seems intent on going nowhere in a hurry, and is stuck some 250 miles south of Cape Hatteras, NC. Steering currents are very weak, and Ophelia is expected to stay stuck through Monday and probably Tuesday as well. Finally, on Wednesday, a trough of low pressure is forecast to push off the East Coast and nudge Ophelia onto a northward track over North Carolina as a Category 1 hurricane, and perhaps on to New England Thursday or Friday as a 50 mph tropical storm. Some forecast models indicate a slow drift towards the coast may occur Monday and Tuesday, which might bring brief heavy downpours to the Carolinas as the outer bands scrape the coast.
How believable is this forecast track? The average forecast track error for a 3-day forecast is 230 miles, which would mean Ophelia could easily make landfall in South Carolina, or completely miss the U.S. The computer models, which were almost unanimously calling for a landfall in South Carolina a day ago, have now switched to calling for a landfall in eastern North Carolina, a shift of some 300 miles in one day! These forecast models do poorly when steering currents are weak, and it would be no surprise if today's official NHC 3-day forecast is in error by 200 or 300 miles. This means that the hurricane could just as easily hit Myrtle Beach, SC as Cape Hatteras, NC--or may even pass harmlessly out to sea. Still, the fact that the models are mostly clustered over eastern North Carolina dictates that I dutifully project that residents there are at highest risk.
Ophelia's intensity remains about the same--the 9am EDT hurricane hunter mission found a central pressure of 978 mb and top flight-level winds of 74 knots, about what they've been the past day or so. Water vapor satellite imagery continues to show dry air on Ophelia's west side, and visible satellite images show a noticable lack of convection on her west side due to the dry air. The Hurricane Hunters found only a partial eyewall on their last fix, a sign that Ophelia continues to struggle with this dry air.
An additional problem for Ophelia is cold water welling up from the depths. She has been sitting in the same area for almost a day, and this has given time for the winds to churn up cold water from deep blow the hurricane. A drifting buoy to the south of Ophelia reported a 3C temperature drop yesterday, and an examination of the latest SST loop from NOAA's Hurricane Research Division shows a number of areas of upwelling cold water from the areas Ophelia has traversed. In particular, a big blue dot offshore from Cape Canaveral is visible, a location where Ophelia sat for two days stirring up cold water.
On the plus side for Ophelia, the upper-level outflow is the best it has looked, and the wind shear plauging her on the west side has dropped to 5 - 10 knots and is forecast to remain low. If Ophelia can drift away from her present location to avoid the cold waters she is stirring up, she may be able to intensity to a Category 2 hurricane. Any intensification beyond that is highly unlikely, and she will most likely remain a Category 1 hurricane through the next two or three days.
Elsewhere in the tropics
The rest of the tropics are unusually quiet in what is usually the busiest week of hurricane season.
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