Tuesday, June 16, 2015

T.S. Bill Targets Texas Coast

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Credit National Hurricane Center

 

# 10,217

 

Although neither large, nor particularly strong , Tropical Storm Bill (which was named overnight) is headed for an already water-logged section of the country, poised to dump additional heavy rains on areas still recovering from last May’s floods.


The latest advisory expects landfall later today. 

 

SUMMARY OF 400 AM CDT...0900 UTC...INFORMATION

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LOCATION...27.9N 95.7W
ABOUT 55 MI...90 KM SE OF PORT OCONNOR TEXAS
ABOUT 110 MI...180 KM SSW OF GALVESTON TEXAS
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES

WATCHES AND WARNINGS
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CHANGES WITH THIS ADVISORY:

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Warning is in effect for...
* Baffin Bay to High Island Texas

A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area.

For storm information specific to your area, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office.

<SNIP>

HAZARDS AFFECTING LAND
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RAINFALL:  Bill is expected to produce total rain accumulations of 4 to 8 inches over eastern Texas and eastern Oklahoma and 2 to 4 inches over western Arkansas and southern Missouri, with possible isolated maximum amounts of 12 inches in eastern Texas.

WIND:  Tropical storm conditions are expected to reach the coast within the warning area in a few hours.

STORM SURGE:  The combination of a storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters.  The water could reach the following heights above ground if the peak surge occurs at the time of high tide...

Upper Texas coast...2 to 4 feet
Western Louisiana coast...1 to 2 feet

The deepest water will occur along the immediate coast near and to the right of the landfall location.  Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances.  For information specific to your area, please see products issued by your local National Weather
Service forecast office.

TORNADOES:  A few tornadoes will be possible across portions of eastern Texas and far western Louisiana today and tonight.

 

Given the rain soaked ground that Bill will be traversing in both Texas and Oklahoma, there are concerns over both additional flooding and the potential for seeing a rare `brown ocean effect’, which could help maintain the storm’s power (or even increase it) as it moves inland.

 

While it is true that most tropical storms and hurricanes quickly lose strength once they move over land, a small percentage are able to avoid that fate – at least temporarily – by drawing on the moisture and heat rising from the ground.

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This explainer comes from NASA.

 

Brown Ocean' Can Fuel Inland Tropical Cyclones

July 16, 2013

In the summer of 2007, Tropical Storm Erin stumped meteorologists. Most tropical cyclones dissipate after making landfall, weakened by everything from friction and wind shear to loss of the ocean as a source of heat energy. Not Erin. The storm intensified as it tracked through Texas. It formed an eye over Oklahoma. As it spun over the southern plains, Erin grew stronger than it ever had been over the ocean.

Erin is an example of a newly defined type of inland tropical cyclone that maintains or increases strength after landfall, according to NASA-funded research by Theresa Andersen and J. Marshall Shepherd of the University of Georgia in Athens. 

Before making landfall, tropical storms gather power from the warm waters of the ocean. Storms in the newly defined category derive their energy instead from the evaporation of abundant soil moisture – a phenomenon that Andersen and Shepherd call the "brown ocean."

"The land essentially mimics the moisture-rich environment of the ocean, where the storm originated," Andersen said.

The study is the first global assessment of the post-landfall strength and structure of inland tropical cyclones, and the weather and environmental conditions in which they occur.

(Continue . . . )

 

All of this is important because – as we discussed during National Hurricane Preparedness Week last month - Inland Flooding often produces some of the greatest damage and loss of life from these tropical systems, sometimes hundreds of miles inland from where they came ashore.

 

When it comes to getting the latest information on hurricanes, your first stop should always be the National Hurricane Center in Miami, Florida.

 

And if you are on Twitter, you should also follow @FEMA, @CraigatFEMA, @NHC_Atlantic, @NHC_Pacific and @ReadyGov.

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