Debris flows caused by rainstorms are a frequent and devastating hazard in the Southern Appalachian Mountains of North Carolina. Through June, NSSL is partnering with the Integrated Precipitation and Hydrology EXperiment (IPHEX) to understand warm season precipitation caused by complex terrain in the area, and the relationship between precipitation patterns and hydrologic processes.
Current precipitation estimates are significantly poor in the inner mountain region of the Southern Appalachians where National Weather Service WSR-88D radar data is used in hydrologic forecast models. NSSL researchers are collecting data with the NOAA X-Pol (NOXP) mobile radar in the Pigeon River watershed basin of North Carolina until mid-June to test the role of gap-filling radars to better define rainfall runoff for these models.
Since 2007, a high elevation tipping bucket rain gauge network has been recording observations in the Pigeon River Basin. Instruments that measure microphysics have also been used during intensive observing periods in this and surrounding river basins during different seasons, focusing on ridge-ridge and ridge-valley variability. These observations have helped define the variability of rainfall intensity and accumulation at scales ranging from annual to daily.
So far, researches have discovered the importance of light (<3 mm/hr) rainfall as a baseline freshwater input to the region, and that the active depth of the atmosphere varies considerably in space from ridge to ridge.
Results from the modeling work have identified coalescence as a driving process in warm light to moderate rainfall. The localized importance of the region’s persistent fog interacting with low level clouds has also been identified. The fog and cloud interactions intensify and even trigger precipitation events that are often experienced only at high elevations and contribute significantly to the yearly water budget in the region.
The data gathered by NSSL will help researchers improve the accuracy of models used to predict flash floods and debris flows.
10-year project expected to reveal important findings beneficial to the United States
NOAA, NASA and the University of Connecticut are representing the United States in the Hydrological Cycle in the Mediterranean Experiment (HyMeX), the largest weather field research project in European history.
HyMex is a 10-year international effort to better understand, quantify and model the hydrologic cycle in support of improved forecasts and warnings of flash floods in the Mediterranean region.
The project targets central Italy, southern France, the Balearic Islands, Corsica and northern Italy — all areas particularly susceptible to devastating flash flood events. Improved understanding of the land, atmosphere and ocean interactions that contribute to flash flooding in this part of the world will advance the state of the science that will ultimately be represented in forecast models with application in the United States.
NOAA National Severe Storms Laboratory (NSSL) researchers will operate a mobile radar, NOAA – XPol (NOXP), in southeast France from Sept. 10 to Nov. 10. This is the first of several special observation periods during the HyMeX 10-year timeframe. Additionally, NOAA’s Satellite and Information Service is sponsoring scientists from New Mexico Tech to operate and evaluate a Lightning Mapping Array during HyMeX to support product development and validation for the future Geostationary Lightning Mapper on NOAA’s GOES-R satellite, which is scheduled to launch in late 2015.
The radar will provide high-resolution data and low altitude scans to help determine the size of the raindrops, the intensity of rainfall, and rainfall rates to help predict flash flooding conditions in the Cévennes Vivarais region of France.
During autumn, onshore moisture from the Mediterranean Sea encounters the 5,000-feet high Cévennes Mountains in southeast France making numerous towns and villages particularly subject to severe flash flood events.
“Data collected in the air, at sea and on land will shed light on how catastrophic flash-flooding events begin, which may help local officials better prepare for and respond to these types of emergencies,” said Jonathan Gourley, Ph.D., an NSSL research hydrologist.
Other sensors include three instrumented research aircraft, three research ships, buoys, ocean sensors, additional mobile precipitation radars, cloud radars and microradars, hundreds of rain gauges, ten disdrometers (to measure size and speed of individual raindrops), a dozen lidars, sonar, instrumented balloons, wind profilers, and a lightning mapping array.
NSSL’s participation in HyMeX is sponsored by MétéoFrance, and operations are coordinated with the Cévennes-Vivarais Mediterranean Hydro-Meteorological Observatory, The University of Grenoble, NASA, University of Connecticut and Cemagraf.
NOAA’s National Severe Storms Laboratory (NSSL) has a ten-year cooperative research venture with the Salt River Project (SRP), an Arizona power and water utility, to develop weather decision support tools for the company’s power dispatch, transmission operations, and water diversion. In 2011, an NSSL-produced prototype algorithm that provided advance notice to prepare for the impact of a severe dust storm in Phoenix. This week, NSSL launches a month-long study using mobile radar to verify its microburst and haboob prediction algorithms. These data help SRP serve 920,000 electric customers in the Phoenix area and deliver nearly 1 million acre-feet of water annually to a service area in central Arizona.
NSSL’s dual-polarized mobile Doppler radar team coordinated operations with the Phoenix National Weather Service (NWS) Forecast Office and the NWS Radar Operations Center during dust storm events during July and August. Their mission was to collect data on the vertical extent of the dust to compare with the Phoenix NWS radar data, recently upgraded with dual-polarization technology.
To date, data has been collected on seven dust storms, with four of them being considered as “major.”
NWS forecasters observed a mysterious shadow in the radar data during the dust storm on July 19, 2011. They also re-examined dual-polarized radar data from the large dust storm on July 5, 2011. During that event, the shadows were more pronounced, and along and slightly behind the leading edge of the dust storm.
NWS forecasters hope combining both data sets will reveal some clues about their existence.
Seven destructive tornadoes struck Oklahoma on May 24, 2011. The tornadoes were well forecast by the National Weather Service (NWS), and NSSL was in position to capture the storms in several ways.
NSSL’s dual-polarized X-band mobile radar captured the early and mature stages of the first tornado reported near Canton Lake, Okla. The data will be compared with another X-band dual-polarized radar for accuracy. This storm produced an EF-3 tornado.
The phased array radar successfully sampled a tornadic supercell every one minute as it evolved and went on to produce devastating EF-4 damage in towns west of Oklahoma City, Okla. A comparison of PAR data with the damage path shows that the radar captured rotation in the storm 12 minutes before it touched down. This tornado was on the ground for two hours with a 75-mile long track.
Visiting forecasters in the NOAA Hazardous Weather Testbed 2011 Spring Experiment found it interesting to be under the threat of tornadoes and then to be in the forecast path of them. They watched the storms out the window and on the National Weather Radar Testbed Phased Array Radar along with the area Terminal Doppler Weather Radar and the NWS NEXRAD. These radars showed the evolution of two confirmed tornadic debris balls as both storms moved towards Norman, Okla. Participants also reported the NSSL/CIMMS weather-adaptive 3D variational data assimilation system (3DVAR) products all handled the track and evolution of the storms and tornadoes very well.
The American Red Cross of Central Oklahoma began using NSSL’s Warning Decision Support System – Integrated Information (WDSS-II) to map rotation tracks of the storm and deploy their teams by 8 a.m. the next day.
And, several NSSL scientists have been in the field as part of NWS teams to survey the tornado tracks and assign EF-Scale ratings based on the damage they find. The EF-Scale is an estimate of the strength of the tornado based on damage to structures and vegetation. Preliminary results show three tornadoes out of the seven in central Oklahoma were ranked a violent EF-4.
Dual-polarized weather radar can estimate the number of bats in a swarm similar to the way it can estimate the number of raindrops in a cloud. This information is valuable to biologists, ecologists and entomologists as they try to understand how populations and behaviors of bats and insects are affected by changes in climate over time.
Several mobile radars, including NSSL’s dual-polarized mobile radar were used in a project to track swarms of millions of bats as they emerged from their caves each night to feast on insects. The radar images of bats appear as distinct “blooms.”
Usually data from birds, insects or bats are considered “clutter” and are filtered out. NSSL researchers have reversed the filter to now focus on the bioscatter. Using calculations of radar backscatter from a single bat in the laboratory, made by the University of Oklahoma, the group is developing the first means to calculate aerial densities of bats as they travel.
NSSL will use the data to enhance algorithms that remove the bioscatter clutter to see the weather more clearly.
“What we see in the dual-polarized fields provided by NSSL’s radar, and soon with WSR-88D dual-polarization, will bring a whole new era in behavioral ecology and conservation as well as radar quality control,” says NSSL’s Ken Howard.
The National Science Foundation sponsored project includes researchers from several Universities, the National Park Service and the USGS.
“The summer night sky is filled with a spectrum of biological life that is in many ways equivalent to what we observe in coral reefs,” says Howard. The data we collected has brought a new appreciation of the rich diversity of life and that can be seen using radars, and especially dual-polarized radars.”
NSSL deployed the NOAA X-Pol mobile radar in southwestern Colorado over the weekend as part of the Southwest Colorado Radar project to collect data on snowfall in the area. The project continues through the end of February, 2011.
The NOXP is equipped with dual-polarization technology, which provides detailed information about the water content of snow, providing better estimates of precipitation amounts. Data from NOXP is being processed through NSSL’s NMQ/Q2 multi-sensor precipitation estimation system.
Forecasters will use the information to enrich their winter weather forecasts. Local data users include county search and rescue and airport operations.
The mobile radar was also used during the summer phase of the project to demonstrate the potential usefulness of gap-filling radars in rugged terrain. Southwest Colorado is not optimally observed by surrounding NWS WSR-88D radars due to numerous mountain ranges, leaving uncertainties in surface precipitation rates.
Project sponsors include the Colorado Water Conservation Board, Colorado Division of Emergency Management, Southwestern Water Conservation Board, Durango – La Plata County Airport and the Southern Ute Indian Tribe.
Researchers from NSSL’s Radar Research and Development Division are perfecting their radar relay handoff as they rotate through Birch Bay, Washington to operate the NOAA-Xband dual-POLarized (NO-XP) mobile radar in support of the 2010 Winter Olympic and Paralympic Games.
NSSL was invited to use the NO-XP to participate in SNOW-V10, the Science and NOWcasting of Olympic Weather for Vancouver 2010 in support of nowcasting operations for the Cypress Mountain venue, where freestyle skiing, snowboard, and snowboard halfpipe competitions are taking place. The NO-XP radar operates on a sensitive wavelength to detect smaller particles such as snow. The dual-polarization capability provides valuable details on the size and shape of these particles.
The NO-XP radar is currently located in Birch Bay, Washington, with an unobstructed view to the northwest towards Cypress Mountain near Vancouver. The team sends the radar data to forecasters via wireless internet in real time to identify the melting level and how it changes with time. They also call attention to precipitation moving in from the west that may not be seen by the Canadian radar because of the mountains.
Researchers have their own team goal to accomplish – the want to understand the generation and evolution of snow and rain in mountainous terrain.
“Location and evolution of the melting zone is crucial and it can be mapped very well with a polarimetric radar. Verification of the signatures can be made in this particular location because the Olympic forecasting team has instruments on much of the mountain, and at many heights and locations. It will be a great comparison to improve verification and help understanding,” said Dusan Zrnic, part of the NSSL team.
The radar will remain in Birch Bay through the Paralympic Games set for March 12-21 2010.