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 , 9:50 PM GMT on August 03, 2006
Hi, this is Rob Carver, filling in for Jeff Masters this afternoon.
TS Chris, while weak, is still barely a tropical storm in NHC's eyes.
The hurricane hunters didn't find any winds of tropical storm strength,
but NHC felt it was still possible there were some strong enough winds
in the circulation to maintain it's status. However, the forecast still
calls for Chris to weaken to a tropical depression within the next 12
TS Chris continues to be very weak and disorganized with the bulk
of its thunderstorms away from the center of circulation. Below is
a satellite-derived estimate of the rainfall rate, which shows this.
Also, radar imagery from San Juan, PR shows no significant changes in the
intensity or organization of the thunderstorms on the SE side of Chris.
Right now, the wind shear around Chris is about 10 knots which is
decreasing which would be favorable for Chris. However, there is
an area of significant shear (about 40 knots) SE of Florida which
would be not be favorable for an already weak storm.
Model guidance is fairly consistent in bringing Chris or it's remnant
south of Florida and into the Gulf of Mexico. Some models, such as the
GFS have Chris dissipating relatively soon.
The August update of the long-range hurricane forecast issued by
Dr. William Gray's group at Colorado State University has been updated here.
The forecast has been adjusted downwards slightly, to account
for less favorable conditions for hurricanes in the Atlantic basin.
The new forecast calls for 15 named storms, which is two less than the May 31 forecast of 17 storms. Gray's group also predicts 7 hurricanes and 3 Category 3 or greater hurricanes for this season, which is two fewer than the May 31 forecast.
Gray's group cites four main reasons for this shift. First,
the sea-level pressure over the tropical Atlantic has risen,
which is less favorable for the formation of tropical cyclones.
Second, the speed of the trade winds has increased, enhancing the
vertical wind shear which tends to weaken tropical cyclones. Third,
the sea-surface temperatures (SSTs) of the tropical Atlantic has
fallen, which lowers the amount of energy availible for storms.
Finally, the SSTs over the eastern equatorial Pacific are starting
to rise. This would tend to cause changes in the upper-level winds
which would generate more wind-shear in the tropical Atlantic.
Of course, we will have to wait and see how accurate this forecast
is. The next scheduled update is September 1.
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