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 , 1:11 PM GMT on September 07, 2005
TD 16 gathered enough strength last night to be given a name--Ophelia. Ophelia will be a name we will hear a lot of over the coming week. She is going to cause plenty of trouble, and will be moving slowly enough that we'll still be talking about her a week from now.
Ophelia is a weak system at present, and is suffering from strong upper-level winds on her south side that are shearing away any convection that tries to develop there. Almost all the action is on the north side of the storm, as the northeast coast of Florida can attest to. Nearly three inches of rain has fallen along some coastal areas, from squalls that have rotated in from the ocean. Winds gusts at the St. Augustine pier were as high as 35 - 40 mph overnight. Sustained winds over the ocean areas off shore are 40 - 45 mph, and 12 foot seas have been observed. Large waves from Ophelia will start to pound the coast from northern Florida to North Carolina over the next five days, creating beach erosion problems. The rains will continue to fall across the north Florida coast, and minor flooding will make driving slow and hazardous by tomorrow in some areas of north Florida.
Figure 1. Total rainfall from Ophelia as estimated by the Jacksonville Doppler radar.
Long range radar out of Melbourne shows a slow increase in intensity and coverage of the rain, and a few spiral bands trying to form on the south side of the storm. Over the next two days, Ophelia should continue to slowly intensify, battling the shear from the strong winds on her southern side. Interference from Nate does not seem to be a problem; the upper-level outflow on Nate's west side has diminished and does not appear to be shearing Ophelia. The ocean has plenty of deep warm water (29 - 30C) under Ophelia, so the intensification potential is high if the shear drops.
The long term track and intensity forecast for Ophelia are highly uncertain. The computer model map has the appearance of a squashed spider, with each model taking Ophelia a different direction. The GFDL and BAMS Medium solutions take Ophelia westward across Florida and into the Gulf of Mexico almost immediately. These solutions are already incorrect, and are being discounted at this time. The Canadian model takes Ophelia out to sea behind Nate, but is the only model calling for this track. What I believe is the most likely scenario is one that is not promising for the U.S., and is favored by the GFS, UKMET, and NOGAPS models. These models forecast that steering currents over Ophelia will remain weak the next two days, which will allow her to remain over the warm ocean waters and slowly gather strength. A weak trough of low pressure is forecast to move off the east coast Friday, which should act to push Ophelia away from the coast slightly. This trough could also create some shear and dump cold, dry air into the cyclone, weakening it temporarily. However, the GFS, UKMET, and NOGAPS models forecast that this trough will bypass Ophelia, and a ridge of high pressure will build back in forcing Ophelia westward or south-westward back toward the U.S. coast. With so much time over warm water, and the shear likely to decrease once the trough bypasses her, Ophelia will have a good chance of attaining at least Category 1 hurricane status and making landfall somewhere on the Southeast U.S. coast. All interests along the Southeast coast from Miami to Cape Hatteras need to watch this storm.
I'll be back early this afternoon with an update, and info on Nate and Maria and the rest of the tropics.
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