Weather Research Center
3227 Audley Houston, Texas  77098   
Phone: (713) 529-3076   Fax: (713) 528-3538     

****  FLASH ******
Thursday September 10, 1998
FOR INFORMATION CONTACT
Jill Hasling (713) 529-3076 
email:  wrc@wxresearch.com    web page:  http://www.wxresearch.com

High tides from Frances?
How can a tropical storm 200 miles to the south cause such tides?

HOUSTON - There are reports that indicate tides along the coast have not 
been this bad since Hurricane Alicia made landfall in August 1983, even 
with the center of Tropical Storm Frances some 400 miles south of Galveston.    
According to Dr. John C. Freeman, Director of Research at the Weather 
Research Center, the winds bombarding the upper Texas coast are due to a 
tight pressure gradient from the circulation of Tropical Storm Frances 
(low pressure system) and a high pressure system over southeast US.  
A strong pressure gradient is caused when you have a relatively high 
pressure system  with a very low pressure system in proximity.  The 
difference in the two pressures causes strong winds.  "When you have a 
tight pressure gradient the winds blow faster," said Dr. Freeman.  "In 
this case, strong easterly winds are blowing toward and along the Upper 
Texas Coast.  The winds have been blowing from the east across the Northern 
Gulf for the past 50 hours.  These winds blow the water up along the coast 
and the water piles up causing tides to run well above normal," he added.  
On top of the tides there is also wind wave action which pushes up the 
water over low lying roadways and into Galveston Bay.

The Houston-area drainage system depends on the bayous emptying into the bay 
and the gulf.  If the water is pushed up, there is no place for the rain 
water to drain .  This will result in flooding of the streets that normally 
flood when there is a lot of rain.  Frances is currently stationary and is 
not moving anywhere fast.  This will cause the strong easterly winds to 
continue and the tides should increase by one foot to one and half feet per 
day.  A stalled system like this results in higher tides along the Upper 
Texas Coast than a landfalling Category 1 hurricane because the water 
continues to pile up and has no where to go.  Flooding from any heavy 
downpours could also result in flooding since there will be no place for 
the water to drain.
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w can a tropical storm 250 miles to the south cause such ti