Bill Accelerating Northward, East of Carolinas
By Greg Postel, Hurricane Expert
Hurricane Bill continues to track well offshore the U.S. coast ...
As of 11 a.m., the center of Hurricane Bill was located about 435 miles south of Nantucket, Mass. The current northward movement at 23 mph should soon bend northeastward away from the U.S. Nonetheless, the large size of the circulation might allow (40% chance according to the National Hurricane Center) tropical storm conditions to glance the eastern-most coast of Massachusetts for a brief period early Sunday morning -- where a tropical storm warning is in effect. Watches and warnings are also in effect for parts of Nova Scotia, Prince Edward Island and Newfoundland in Canada.
Keep reading for more on Hurricane Bill...
The hurricane's latest infrared satellite presentation looks less than impressive, with an asymmetric distribution of deep convection and distinct dry-air intake bands.
The ingestion of dry air near the surface of the storm has stabilized it in a way that has led to sharp vertical differences in wind speed. Measurements (GPS dropsondes) from recent reconnaissance missions have shown that the winds near the surface are 30-40 mph lower than they are at 1,000 feet in many parts of the inner core. Latest measurements indicate that the maximum sustained winds are in the 95-105 mph range. As Bill moves toward cooler water and approaches a more unfavorable nontropical environment in the next 24-36 hours, the system is expected to weaken rather rapidly.
In retrospect, Bill never really possessed the qualities we often see in major hurricanes (e.g., vigorous updrafts surrounding a symmetrical and humid inner core). The circulation always seemed to be fighting off the destructive effects of a nearby Saharan air layer. One wonders if this is the mode of storm that we'll be seeing this year ... the re-curving Cape Verde type with a largely hostile surrounding environment?
Capital Weather Gang
| August 22, 2009; 11:00 AM ET
Categories: Tropical Weather
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