Hurricane forecasters now using long range lightning data

HELSINKI, FINLAND–(EMWNews – July 16, 2008) –

(Tucson, AZ, July 16, 2008) Vaisala’s Long Range Lightning

Detection

Network (LLDN) data are of increasing interest to the National

Hurricane Center (NHC). The LLDN provides detection capability far

offshore into the Atlantic Ocean and eastern Caribbean Sea which

assists in a better understanding of hurricane intensity changes.

Vaisala provides real-time, long range lightning data to the NHC

as

part of its contract to provide lightning data to the National

Weather Service (NWS). NHC began displaying LLDN data in its

operations in April 2007. NHC tropical cyclone and marine

forecasters have been evaluating the data since then, making use

of

the ability to overlay lightning data on visible and infrared

satellite imagery. Operational tropical meteorologists conduct

analyses and forecasts over very large but data-sparse oceans, and

the LLDN data provide a new data source to help assess the

structure

of tropical cyclones and other weather systems at sea.

To better understand the relationships between lightning activity

and

tropical cyclone strength and structure, scientists from Vaisala’s

applications and technology team conducted a study in 2004 that

linked lightning trends near the center of hurricanes to hurricane

intensity. The study combined data reported by NHC in strong

hurricanes with eyewall lightning data gathered by Vaisala’s LLDN,

which measures lightning strikes from cloud to ground.

Shortly after this study, Vaisala scientists began interacting

with

NHC forecasters to examine a larger number of tropical cyclones

during the 2005 through 2007 hurricane seasons. As a result of

the

interaction, Vaisala developed a web-based product for real-time

use

by NHC forecasters to monitor eyewall lightning within tropical

cyclones. As time has permitted, NHC forecasters have been

viewing

these products during operational shifts, to evaluate how the

lightning data may complement other tools used to analyze tropical

cyclone strength and structure.

These evaluations reveal that enhanced lightning activity in

tropical

cyclones appears to occur at certain times within their life

cycle,

such as when strong tropical storms are on the verge of reaching

hurricane status, and when strong hurricanes undergo significant

changes in their internal structure. It has also become apparent

that tropical cyclones are more prolific lightning producers than

previously thought, and that periods of enhanced lightning do not

occur randomly. Further research will assess the value that long

range lightning data may provide for improved tropical cyclone

track

and intensity forecasts.

“Based on the interest expressed by some NHC forecasters, Vaisala

has

expanded sensor technology into the Caribbean to increase

detection

for coastal and tropical storms. Forecasters now have more

frequent

and reliable lightning information from within the eyewalls of

hurricanes over a larger portion of the Atlantic basin. As a

result,

continuous information on the tropical cyclone’s inner structure

can

now be monitored that is obscured on visible and infrared

satellite

imagery,” noted Nicholas W.S. Demetriades, manager of applications

and technology for Vaisala.

Vaisala Dropsonde is another tool that has been used for hurricane

measurement by different weather and research authorities for

several

years. A dropsonde is released from an aircraft flying above a

hurricane. It descents through the hurricane by a special

parachute,

transmitting meteorological data.

Media Contacts:

-- Nicholas W.S. Demetriades, Vaisala, Inc. Manager Applications &

   Technology, tel +1 520 806 7300,

   nicholas.demetriades (a) vaisala.com

-- Theresa Mary Fischer, Vaisala, Inc. North American Corporate

   Communications Manager, tel +1 520 806 7300,

   theresa.fischer (a) vaisala.com

Vaisala is a global leader in environmental and industrial

measurement, providing services, products and solutions for

meteorology, environmental sciences, aviation, traffic and

industry.

Built on science-based innovation, advanced technology and over 70

years of experience, Vaisala is committed to providing a better

quality of life through environmental measurement. Headquartered

in

Finland, Vaisala employs over 1100 professionals and is listed on

the

Nordic Exchange, Helsinki. www.vaisala.com

Copyright © Hugin AS 2008. All rights reserved.