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 , 28. syyskuuta 2011 klo 11:39 (GMT)
Ophelia is back as a tropical depression, thanks to a reduction in wind shear that allowed the storm to re-organize yesterday afternoon just east of the Lesser Antilles Islands. Martinique radar shows a large area of concentrated thunderstorms lies about 200 miles to the east of the northern Lesser Antilles, with good spiral banding and rotation. Recent satellite loops show that Ophelia's heavy thunderstorms are not increasing, and are limited in areal extent. The low-level center is partially exposed to view, thanks to strong wind shear. No hurricane hunter flights are scheduled for today.
Figure 1. Morning radar image from the Martinique radar shows the heavy rain showers from Ophelia, just east of the northern Lesser Antilles. Image credit: Meteo-France.
Dry air and moderate wind shear of 15 - 20 knots are slowing down Ophelia's intensification, and will continue to do so through Thursday. By Friday, wind shear is expected to fall to 10 - 15 knots, and most of the models give strong support to Ophelia intensifying into a hurricane by Saturday. With the models all agreeing on at track for Ophelia just east of Bermuda, Tropical Storm Warnings will probably be required for the island this weekend. Bermuda will be on the left (weak) side of Ophelia, so will miss the storm's strongest winds and heaviest rains. Ophelia may be a threat to Southeast Newfoundland early next week.
In the far eastern Atlantic, Tropical Storm Philippe is headed northwest into the middle of the North Atlantic, and is not expected to trouble and land areas. Wind shear is high enough over Philippe that the storm may dissipate by 4 - 5 days from now.
Typhoon Nesat headed towards China
Typhoon Nesat is headed west towards a landfall on China's Hainan Island on Thursday, and in northern Vietnam just south of Hanoi on Friday. Nesat is a large but disorganized Category 1 storm, and will not have time to strengthen significantly before landfall. However, Nesat is a very wet storm, capable of dropping over a foot of rain in 24 hours, according to latest satellite rainfall forecasts. Nesat roared across Luzon Island in the Philippines Monday as a powerful Category 3 typhoon with 120 mph winds, leaving 20 people dead and severe flooding problems.
Figure 2. Predicted rainfall amounts for the 24 hours ending at 06 UTC on Thursday September 29 show the Nesat is expected to dump over a foot of rain (red colors) along where its southern eyewall tracks. Image credit: NOAA/NESDIS.
Eastern Pacific's Hurricane Hilary steadily weakening
In the Eastern Pacific, Hurricane Hilary has weakened to a Category 1 hurricane with 90 mph winds. Continued weakening will occur over the next few days, and all of the models show Hilary dissipating before reaching the coast. Moisture from Hilary will not reach the U.S.
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