Media Day: Thursday, June 1, Goodland, Kansas
Contact:
Anatta
Telephone: 303-497-8604
Fax: 303-497-8610
E-mail: anatta@ucar.edu
BOULDER--Scientists are scanning the skies for lightning and supercell storms from a host of high-tech platforms in the High Plains near Goodland, Kansas, from May 22 to July 15. Their tools include storm-chasing vehicles, radars, and an armored research aircraft. The Severe Thunderstorm Electrification and Precipitation Study (STEPS-2000) is the largest effort to date to study lightning and low-precipitation storms. The National Center for Atmospheric Research (NCAR) is one of the project's leaders, with funding from the National Science Foundation, NCAR's primary sponsor.
Besides NCAR, participating institutions include the National Weather Service (NWS), the National Severe Storms Laboratory (NSSL), Colorado State University (CSU), the New Mexico Institute of Mining and Technology (NMIMT), and the South Dakota School of Mines and Technology (SDSMT). NCAR researchers Morris Weisman and Jay Miller and CSU's Steve Rutledge will direct field operations.
Low-precipitation storms have many of the earmarks of other intense supercells-- including hail, strong updrafts, and rotation--but they produce little rain. "We can't now differentiate between low-precipitation and other storms," explains Weisman. "With the newer technology we're focusing on these storms, we expect to observe features we've only theorized about until now."
STEPS-2000 is based at the NWS office in Goodland, Kansas, and at an operations center near Burlington, Colorado. The study area-- along the semipermanent dry line that marks the west edge of Tornado Alley--has one of the nation's highest frequencies of positive cloud-to-ground lightning, a primary research focus during STEPS.
Clues
to storm behavior in precipitation and lightning
Researchers know little about low-precipitation supercells, except that they
seldom produce tornadoes or flooding. Sorting out the microphysics of downdraft
generation and precipitation in these "dry storms" could improve forecasters'
ability to predict what happens to supercells as they evolve.
"We want to know how and why low-precipitation storms don't produce much rain, even when they contain as much water vapor as classic storms," says Weisman. Miller, Weisman, and colleagues will replicate STEPS data in computer models. They will look for differences between low- and high-precipitation storms and track the growth and movement of precipitation in three dimensions. According to Miller, the modeling will help to unravel how storms transport electrical charge and "grow" precipitation, especially hail.
Can
lightning help tornado forecasters?
STEPS-2000 will be the largest research effort to date focused on lightning,
and tornado forecasters may benefit from the effort. Low-precipitation storms
produce more than their share of positive cloud-to-ground strikes. Recent studies
at NSSL have found several cases in which a storm's predominant cloud-to-ground
strikes suddenly shifted from positive to negative within minutes of tornado
formation. A shift may be a good indicator of when a violent tornado might appear
in some storms. If scientists can follow a storm as it produces a tornado, the
link between a storm's electrical behavior and microphysics should become clearer,
and that knowledge could translate in the future into better tornado forecasting.
A
battery of research technology
Three radar systems
A combination of radar systems will be used to determine the internal flow and
precipitation structure of target storms. An NWS Doppler radar based at Goodland
will be joined by two special research radars, both multiparameter Dopplers,
brought in just for STEPS-2000. NWS, NCAR, CSU.
Storm-chasing
vehicles
Chase vehicles will collect hail and observe meteorological conditions and precipitation
directly beneath storms. CSU, NSSL, University of Oklahoma (OU).
T-28
armored aircraft
The T-28, which can survive golf-ball size hailstones, will probe storms at
altitudes up to 20,000 feet. SDSMT.
Two
weather-balloon vans
Two vans will launch weather balloons carrying disposable devices that will
radio data to the operations center about environmental conditions on either
side of the dry line. NCAR.
3-D
lightning mapping system
The lightning mapping system will detect up to 10,000 energy pulses per second
to plot the three-dimensional distribution of lightning. NMIMT.
Balloon-borne
electric field measurements
Special instruments will measure electric fields inside the storms. NMIMT, NSSL,
OU.
Lightning
detection networks
Scientists will use the National Lightning Detection Network to track the location
and polarity of cloud-to-ground strikes and the CSU flat plate antenna network
to quantify intracloud discharges. Global Atmospherics.
Low-light
optics
The Yucca Ridge Field Station near Fort Collins, Colorado, will provide low-light
optical recording at night of storm-top electrical phenomena, such as jets and
sprites. FMA Research.
World
Wide Web
STEPS organizers plan to update lightning data on a real-time weather Web site
every minute to help researchers track the storms on radar and in the aircraft.
They'll also use the site to post STEPS weather-balloon data which, along with
satellite images and other observations from the national operational systems,
will be used to "nowcast"weather conditions in the study area. NMIMT, NCAR.
NCAR is
managed by the University Corporation for Atmospheric Research, a consortium
of more than 60 universities offering Ph.D.s in atmospheric and related sciences.
-The End-