Featured Research

from universities, journals, and other organizations

New Tools Developed To Forecast Hurricane Rainfall Inland

Date:
June 20, 2007
Source:
University of Florida
Summary:
All eyes are on where hurricanes make landfall, but the massive storms actually cause the most deaths inland, where severe flooding often surprises residents. Now, researchers are learning how to predict where tropical storms and hurricanes will dump the most rain — even days after — and hundreds of miles away from — landfall.

All eyes are on where hurricanes make landfall, but the massive storms actually cause the most deaths inland, where severe flooding often surprises residents.

Now, researchers are learning how to predict where tropical storms and hurricanes will dump the most rain — even days after — and hundreds of miles away from — landfall.

In a paper in the current issue of the journal Professional Geographer, Corene Matyas, an assistant professor of geography at the University of Florida, outlines new tools to predict how the storm’s intensity, distance it has moved inland and landscape topography alters its “rain shields” — the bands of heavy rain so visible in Doppler radar images. Among other things, her tools proved adept at modeling observations that when hurricanes or tropical storms encounter the Texas hill country or the Appalachian Mountains, their rain shields tend to line up in the same direction and with the same orientation as the underlying topography.

“There are a lot of different things that can affect where the rainfall can occur in the storm and how heavy that rainfall will be,” Matyas said. “Our goal is to work toward predicting how those factors will determine the rainfall pattern.”

Historically, hurricanes have proven most fatal at landfall, with coastal residents overcome by storm surge and high winds. But over the past four decades, forecasters have become more skilled at predicting hurricanes’ tracks over open water, enabling most coastal residents to flee or prepare for the storms well in advance.

As a result, the highest proportion of hurricane and tropical fatalities has shifted inland. One study cited in the Matyas paper found 59 percent of deaths from tropical storms or hurricanes between 1970 and 1999 occurred because of heavy rainfall rather than wind or storm surge. As storms track inland, they inevitably ensnare more cities and towns. In 1998, Tropical Depression Charley left 20 people dead near Del Rio, Texas, more than 200 miles from where the storm made landfall, Matyas notes.

Researchers are developing some models for forecasting inland rain patterns, but they have difficulty accounting for the lopsided or elongated shape the pattern often takes, with most if not all rain falling on one side of the storm. A common assumption is that rainfall will decrease as the hurricane moves away from the ocean, which is generally true but may be obviated by other weather systems and local landscape.

Matyas’ goal was to find new tools to improve the models.

She studied radar data from 13 U.S. storms that made landfall between 1997 and 2003, then used a common tool in geography — geographical information systems, or GIS — to measure how rainfall patterns changed. GIS is a computer system that makes it possible to analyze spatial patterns of data. It is often used to track things such as voting patterns, but using GIS in meteorology — where spatial patterns change — is relatively new, Matyas said.

Matyas outlined the edge of the rain shields using radar data, then measured their shapes by calculating characteristics such as the position of their center of mass. She repeated the analysis for each hour that the storms were over land. She then used a statistical technique, discriminant analysis, to determine which shape and size best place the storms into groups based on their intensity, how far they travel inland and the topography they encounter. The success of the discriminant analyses indicates that these shape measures could serve as predictive tools for future rainfall models.

In a demonstration of the potential, the shape measures helped to confirm that that the orientation of storms’ rain shields corresponds closely to the orientation of the land topography.

With hurricanes crossing Texas hill country, the rain shields tend to line up parallel to the main axis of the hills, running west to east. Storms near the Appalachians also line up parallel to the mountains, whose axis runs southwest to northeast, with the heaviest rain consistently occurring to the west of the track. This is due to a combination of the mountains and a wedge of cold and dry continental air forcing the moist air upward, causing the water vapor to condense and fall to the ground as rain. This phenomenon does not happen with the Texas storms, as the dry continental air masses over Texas are similar in temperature to tropical moist air masses that accompany hurricanes.

Frank Marks, a research meteorologist and director of the National Oceanic and Atmospheric Administration’s Hurricane Research Division, said Matyas’ conclusions “have a lot of merit in terms of understanding the structure, size and shape of the rain shield.”

He said the next step is to add rainfall amount to the variables. The end goal: a model that will provide inland residents with the same targeted advance warnings and watches that coastal residents get today — but for heavy rainfall rather than wind or storm surge.


Story Source:

The above story is based on materials provided by University of Florida. Note: Materials may be edited for content and length.


Cite This Page:

University of Florida. "New Tools Developed To Forecast Hurricane Rainfall Inland." ScienceDaily. ScienceDaily, 20 June 2007. <www.sciencedaily.com/releases/2007/06/070619125642.htm>.
University of Florida. (2007, June 20). New Tools Developed To Forecast Hurricane Rainfall Inland. ScienceDaily. Retrieved October 21, 2014 from www.sciencedaily.com/releases/2007/06/070619125642.htm
University of Florida. "New Tools Developed To Forecast Hurricane Rainfall Inland." ScienceDaily. www.sciencedaily.com/releases/2007/06/070619125642.htm (accessed October 21, 2014).

Share This



More Earth & Climate News

Tuesday, October 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Traditional Farming Methods Gaining Ground in Mali

Traditional Farming Methods Gaining Ground in Mali

AFP (Oct. 20, 2014) He is leading a one man agricultural revolution in Mali - Oumar Diatabe uses traditional farming methods to get the most out of his land and is teaching others across the country how to do the same. Duration: 01:44 Video provided by AFP
Powered by NewsLook.com
How Detroit's Money Woes Led To U.N.-Condemned Water Cutoffs

How Detroit's Money Woes Led To U.N.-Condemned Water Cutoffs

Newsy (Oct. 20, 2014) The United Nations says water is a human right, but should it be free? Detroit has cut off water to residents who can't pay, and the U.N. isn't happy. Video provided by Newsy
Powered by NewsLook.com
Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

3BL Media (Oct. 20, 2014) Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-fuel Impala Video provided by 3BL
Powered by NewsLook.com
White Rhino's Death In Kenya Means Just 6 Are Left

White Rhino's Death In Kenya Means Just 6 Are Left

Newsy (Oct. 20, 2014) Suni, a rare northern white rhino at Ol Pejeta Conservancy, died Friday. This, as many media have pointed out, leaves people fearing extinction. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins