WunderBlog Archive » Category 6™
Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.Alberto nears hurricane strength
The latest report from the hurricane hunters found winds of 74 knots (85 mph) at flight level of 1500 feet, and a central pressure of 997 mb, down 4 mb from the 8am EDT penetration. After surviving some very strong wind shear last night, Alberto has reorganized, and a new center has formed under the deep convection on the east side of the storm. The old center is still visible on satellite imagery, drifting southward over the Gulf of Mexico. Spiral banding has appeared on both visible satellite imagery and the Tampa radar animation.
Figure 1. Accumulated rain so far from Alberto, as estimated by the Tampa radar.
All this strengthening occurred in the face of strong wind shear of 20-30 knots, which is unusual. I was calling for a 10% chance of Alberto becoming a hurricane, but Alberto certainly has other ideas! The storm's central pressure was a very unimpressive 1006 mb last night when I thought the storm might get ripped apart, but the 9 mb drop in pressure since then is an impressive achievement for a storm under 20-30 knots of wind shear. The shear has not changed much in the past 12 hours, nor is it expected to do so over the next few days. This should limit Alberto's intensification. Hurricane Ophelia last year strengthened in the face of similar amounts of shear, and I anticipate that Alberto will grow no stronger than Ophelia. Maximum sustatined winds of 80 mph are probably the highest we will see from Alberto.
The major threat of damage with Alberto now appears to be storm surge, with a surge of 8 - 10 feet possible over portions of the west coast of Florida. The waters off the coast are very shallow for a long stretch, which allows a rather large surge to build up. High winds will be a problem for mobile homes, and cause moderate tree damage and power outages in the affected area. Heavy rain will also be a concern, but as I discussed yesterday, this may be more of a boon than a bane given Florida's moderate drought conditions. Rain amounts of up to six inches have fallen in portions of the Keys and Naples, Florida.
We'll update this blog later today as conditions warrant.
Jeff Masters
Figure 1. Accumulated rain so far from Alberto, as estimated by the Tampa radar.
All this strengthening occurred in the face of strong wind shear of 20-30 knots, which is unusual. I was calling for a 10% chance of Alberto becoming a hurricane, but Alberto certainly has other ideas! The storm's central pressure was a very unimpressive 1006 mb last night when I thought the storm might get ripped apart, but the 9 mb drop in pressure since then is an impressive achievement for a storm under 20-30 knots of wind shear. The shear has not changed much in the past 12 hours, nor is it expected to do so over the next few days. This should limit Alberto's intensification. Hurricane Ophelia last year strengthened in the face of similar amounts of shear, and I anticipate that Alberto will grow no stronger than Ophelia. Maximum sustatined winds of 80 mph are probably the highest we will see from Alberto.
The major threat of damage with Alberto now appears to be storm surge, with a surge of 8 - 10 feet possible over portions of the west coast of Florida. The waters off the coast are very shallow for a long stretch, which allows a rather large surge to build up. High winds will be a problem for mobile homes, and cause moderate tree damage and power outages in the affected area. Heavy rain will also be a concern, but as I discussed yesterday, this may be more of a boon than a bane given Florida's moderate drought conditions. Rain amounts of up to six inches have fallen in portions of the Keys and Naples, Florida.
We'll update this blog later today as conditions warrant.
Jeff Masters
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