Weather technology changes the claims forecast
When confirming weather-related damage, meteorologists have multiple tools at their disposal.
Most people are familiar with Doppler radar from television newscasts because it shows where it is raining. However, Doppler radar, also known as Weather Surveillance Radar — 1988 (WSR-88D), is much more valuable to experienced meteorologists because it can confirm whether a tornado is on the ground, whether hail is present in a thunderstorm, where smoke and chemical plumes from large fires are spreading, and other potentially dangerous weather events.
On average, these images are processed every one to six minutes. Doppler radar works by initially sending a pulse of energy into the atmosphere where it intercepts precipitation or objects in the atmosphere. Some of that energy is scattered back to the radar unit, where an intensity value and corresponding color are then generated based on how large of a particle was identified. This comprises the different colors seen on radar images.
A major upgrade to Doppler radar came in the form of Dual Polarization (dual-pol) radar products in 2010, which brought vertical radar scans to the existing horizontal ones. One of the Dual-Pol products, called Correlation Coefficient (CC), measures how similar the horizontal and vertical pulses of energy are behaving from pulse to pulse. This information helps distinguish between large hail, tornadic debris aloft, rain versus snow, and even biological critters such as mosquito swarms, migrating bats and other large insect migrations.
Radar at work
On May 28, 2019, a large and violent tornado was moving across Kansas, headed toward the Kansas City, Missouri area. Doppler radar detected a well-organized supercell and a possible tornado, so a tornado warning was issued. This warning was soon upgraded to a “Tornado Emergency” when Doppler radar base reflectivity and correlation coefficient images (CC) detected debris being tossed around, confirmation that a tornado was doing damage and headed toward populated areas.
Figure 1 shows very large particles (rain, hail, debris) being detected by base reflectivity radar (left) and correlation coefficient (right) indicating that a tornado was on the ground. A yellow “tornado icon” icon generated by an algorithm appeared on top of the dark red color contours, another sign of a possible tornado.
Precipitation in the form of rain typically shows up with higher values (orange, red and purple colors). Much lower correlation coefficient values (represented by blue and green colors) located underneath the high reflectivity indicates something other than precipitation, such as tornadic debris like leaves, tree limbs, roof shingles or even vehicles being lofted as high as 10,000 to 15,000 feet into the sky.
Having this kind of data updating every one to five minutes is an invaluable tool that meteorologists can use to issue enhanced tornado warnings and alert the public that a tornado is actually on the ground doing damage, and not just ‘possible’. From a forensic meteorology standpoint, Certified Consulting Meteorologists (CCMs) can obtain and analyze this data for use in insurance claims or litigation cases.
Doppler radar is also very useful for tracking smoke plumes from forest fires, wildfires, fires in junkyards, oil refineries and other large structures where significant amounts of smoke rise into the atmosphere. Using the same base reflectivity and correlation coefficient radar images, smoke particulates can be detected above the ground if the radar beam does not overshoot the smoke particles.
On the morning of November 8, 2018, a historic wildfire erupted east of Paradise, California, and ended up burning 153,000 acres, around 18,800 structures and killing 86 people. It is estimated that 27,784 insurance claims totaling $8.3 billion occurred.
The fire reportedly began in Pulga, California, where high winds caused a high voltage line to fall down. Shortly after this incident occurred, smoke plumes became visible on Doppler radar imagery from the Beale Air Force Base radar site in California (Figure 2). As the fire rapidly grew, thick plumes of smoke billowed into the atmosphere where winds coming from the northeast caused the smoke to drift toward the southwest.
Base reflectivity images (Figure 3) show echo returns an hour after the first smoke was detected. The high reflectivity values indicative of very thick smoke over such a large area were tracked as each new radar image was received. As winds shift during a large fire, so will the smoke plume and the smoke will drift over different areas just like a lake effect snow band does. These images could be used to help track smoke plume insurance claims.
Tracking smoke plumes can help adjust insurance claims involving smoke damage. Downloading and analyzing these images, in conjunction with some other weather data, can help determine if smoke ever passed over a loss location, how long it remained over the area or it could help determine when a fire started.
Doppler radar and hail claims
The frequency of hailstorms affecting populated areas and the amount of hail damage from these events continues to skyrocket. In 2018, the National Weather Service reported over 5,000 hail events. Losses reached $1 billion in Colorado and $4 billion in Texas alone. Unfortunately, there were many instances when hail was reported on a specific date but no hailstorm occurred. Too many professionals rely on NOAA storm database records or other automated algorithms that are often unrepresentative of what occurred at a specific location. This is where Doppler radar and various Dual-Pol products really help.
On May 28, 2019, a severe thunderstorm affected parts of Union County in New Jersey and Staten Island in New York. Patches of large hail, some as large as 1.75″, fell in these very populated areas. However, hail did not necessarily fall everywhere that bright red, orange, pink and purple echoes were observed.
High reflectivity values on Doppler radar is one possible indicator of hail, but other radar products and weather records should be used too. The base reflectivity radar image (left) and the correlation coefficient image (right) in Figure 4 both contain unique identifiers of hail aloft. In this instance, under the areas where high reflectivity was observed, lower correlation coefficient values were present as well. Since these images show changes in the horizontal and vertical pulses, it is an indication that irregularly shaped hydrometeors (large hail) are falling. A local storm report of 1.75″ hail was reported in Staten Island, and this report is plotted on the radar map.
As the radar beam from Upton, Long Island, intercepted the large hail in the atmosphere, a significant amount of radar energy was scattered in different directions, but not back to the radar. This feature is called a “three-body scatter spike” (the area circled in black) and is an indicator of large hail.
In a recent case, $500,000 in coverage was paid to a condominium development for a hail claim.
When tasked with proving that the same thunderstorm also caused severe winds and wind damage, Doppler radar research found that this thunderstorm never came within three miles of the property, yet $500,000 had already been paid because the carrier failed to properly retain a meteorologist to do a site-specific meteorological study.
The insurance industry has still not embraced the use of experienced meteorologists and technology when researching weather-related losses. Until this happens, many claims will continue to be paid unnecessarily.
Howard Altschule (HGA@WeatherConsultants.com) is a Certified Consulting Meteorologist (CCM) and the owner of Forensic Weather Consultants, LLC, a New York-based weather expert firm that provides reliable, site-specific historical weather information and reports for claims, litigations and climate studies in the U.S. and abroad.
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