Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather
By: Dr. Jeff Masters , 1:33 PM GMT on September 12, 2005
Don't believe any of the computer forecast models or the official NHC forecast--no one knows where Ophelia is going. Ophelia is trapped between two large and strong high pressure systems, and will continue to behave unpredictably. The 5am NHC discussion called it this way: "None of the reliable dynamical models have been immune from significant track forecast shifts during the past day or two in this very difficult scenario." In other words, we have no idea where Ophelia is going.
A slow westward drift has been the trend the past day or so, and several of the models show a slow westward or northwestward drift the next two days. Thus, it is reasonable to anticipate that Ophelia's outer rain bands will start to impact the North Carolina and South Carolina coasts this afternoon through tomorrow, bringing localized heavy rain and minor flooding. The usually-reliable GFS model's latest run at 06Z (2am EDT) this morning shows Ophelia hitting Charleston as a strong tropical storm Tuesday morning, and the GFDL thinks Ophelia will be a Category 1 hurricane hitting South Carolina Tuesday night. The other models disagree, letting Ophelia wander off the coast the next two days, and forecast that by Wednesday, a weak trough will push off the East Coast and take Ophelia northward across eastern North Carolina and out to sea. However, the models have trended towards making this trough weaker and weaker. There now appears to be a significant possibility that the trough will fail to pick up Ophelia, high pressure will build back in, and she will wander around the ocean waters near Cape Hatteras for a few more days. The Canadian model has a rather omininous solution--the high pressure that builds in will be strong enough to push Ophelia southwestward, across northern Florida, and into the Gulf of Mexico five days from now. I pooh-poohed this solution when I saw it yesterday, but now this forecast cannot be discounted. The Canadian model has been suggesting that the trough would fail to pick up Ophelia for three runs in a row now, and the NOGAPS and UKMET are starting to show the same thing. In any case, none of these models should be taken very seriously; this is an extremely difficult forecast situation, and trying to predict what Ophelia will do five days from now, let alone tomorrow, will involve more luck than skill.
The latest hurricane hunter mission was at 8:30am EDT, and showed a slightly weaker storm with a poorly-formed eyewall, a central pressure of 988 mb, and peak winds of just 48 knots on the west side. The crew will find stronger winds once they penetrate the north eyewall where the strongest winds are, but Ophelia might get downgraded to a tropical storm today.
Figure 1. Surface winds in Ophelia yesterday afternoon as seen from the NOAA hurricane hunter aircraft.
Dry air continues to be Ophelia's bane; a large amount of it has wrapped into the core of the hurricane and disrupted the convection on the west side. There is still plenty of dry air on her northwest side, and this should continue to be a problem for her the next few days. Cold water stirred up from down deep by Ophelia's winds will also continue to be a problem as she wanders over the same ocean area for multiple days. On the plus side for intensification, wind shear remains lows, about 5 - 10 knots out of the northwest. The upper-level ouflow pattern remains good, and the overall organization of Ophelia is strong. Given all these factors, neither significant strengthening or weakening is likely the next two or three days, and Ophelia will remain a strong tropical storm or weak Category 1 hurricane during this period.
Elsewhere in the tropics
Nothing is going on. Large amounts of dry, dust-laden Saharan air cover most of the tropical Atlantic including the Caribbean Sea.
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