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 , 23. syyskuuta 2011 klo 14:09 (GMT)
Tropical Storm Ophelia is weaker today, thanks to dry air and high wind shear. Satellite imagery shows that Ophelia has almost no heavy thunderstorms near its low level circulation center, which is entirely exposed to view. Most of the storm's heavy thunderstorms are in a band several hundred miles to the east and south, with just a few puffs of thunderstorms occasionally popping up near the center. An analysis from the University of Wisconsin CIMMS group shows a high 20 - 25 knots of wind shear due to strong upper-level southwesterly winds. Water vapor satellite images show the center of Ophelia is entirely within a large area of very dry air. We don't have any current buoy, ship, or hurricane hunter observations of Ophelia; the Hurricane Hunters will be making their first flight into Ophelia this afternoon near 2 pm EDT.
Figure 1. Morning satellite image of Ophelia showing the low-level center exposed to view, with all the storm's heavy thunderstorms in a band several hundred miles to the east and south. This is not a healthy-looking tropical storm.
Forecast for Ophelia
The latest SHIPS model forecast predicts that Ophelia will experience high wind shear of 20 - 30 knots over the next five days, and will move into a region with drier air. I believe that the combination of shear and dry air will probably dissipate Ophelia on Saturday or Sunday, as predicted by the ECMWF, GFS, and NOGAPS models. Ophelia will bring a few heavy rain squalls to the Lesser Antilles on Saturday and Sunday. At longer ranges, even if Ophelia dissipates this weekend, it could encounter a lower-shear environment south of Bermuda early next week and regenerate. Ophelia (or its remnants) may may pass close to Bermuda as early as Wednesday. Ophelia may eventually be a threat to Canada, but it is too early to know.
Figure 2. Morning satellite image of Hurricane Hilary at Category 4 strength, with 145 mph winds. Quite a contrast from Ophelia!
Hurricane Hilary hits Category 4 strength
In the Eastern Pacific, Hurricane Hilary has intensified into an impressive Category 4 hurricane with 145 mph winds, and has brought 2 - 3 inches of rain to portions of the Mexican coast west of Acapulco. Hilary is headed west, away from Mexico, and the storm's rains should not cause major flooding problems for Mexico. However, a trough of low pressure expected to move over the Western U.S. early next week may be strong enough to turn Hilary to the north, and both the GFS and ECMWF models predict Hillary could hit Mexico's Baja Peninsula on Thursday. If this scenario does occur, Hilary would likely be much weaker, due to the colder waters it would have to traverse to get to Baja. It is possible that moisture from Hilary could work its way northwards into Arizona, New Mexico, and Texas late next week, bringing some drought relief. Hilary is the fourth Category 4 hurricane in the Eastern Pacific this year, and the second strongest, behind Hurricane Dora, which had 155 mph winds. The GOES-West satellite is in super rapid scan mode today for Hilary, and you can view satellite loops with images taken every minute from the NOAA/CIRA website.
Elsewhere in the tropics
In the far eastern Atlantic, a tropical wave that emerged from the coast of Africa Thursday is predicted by the GFS model to develop into a tropical depression early next week. The disturbance is currently moving west, but steering currents favor a west-northwest to northwest track early next week. NHC gave the disturbance a 10% chance of developing into a tropical depression by Sunday in their 8 am Tropical Weather Outlook.
Japan is cleaning up from Typhoon Roke, which made landfall near Japan’s Hamamatsu City in Shizuoka Prefecture at 2:00 pm local time (05:00 UTC) on September 21. Maximum sustained winds at landfall were 180 km/h [112.5 mph], making Roke a strong Category 2 storm. AIR-Worldwide is estimating that insured damages from Roke were $150 - $600 million, mostly from wind damage. The typhoon killed 12 and left 5 people missing in Japan.
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