Monthly Archives: June 2014

Is Europe Due for Severe Hailstorms this Summer?

Summer has just started, but weather has already been warm over Europe. Many countries have experienced very high temperatures over the first weeks of June, and there is a chance the 2014 summer will be warmer than normal. A warm atmosphere can bring very high convection potential and potentially lead to a busy severe convective storm season. While seasonal forecasts are uncertain, severe hail events already experienced in June already point to a potential increase in hail risk this year.

The first noticeable hailstorm of the season hit Germany, France, and Belgium between June 7 and 9. Over that period, southern air masses were very warm and clashed with much cooler air from the north. This frontal system brought heavy local wind, rain, and hail, especially over the north of France, Belgium, and northwest region Germany, where large cities like Essen, Düsseldorf, or Köln experienced property damages and six casualties.

RMS scientists Dr. Navin Peiris and Panagiotis Rentzos led a reconnaissance survey in the region a few days after the event and noted that even if there was some evidence of direct hail damage to roofing, most of the substantial damages and transport disruption around Düsseldorf came from tree falls due to very strong wind gusts.

Tree Fallen in Hailstorm

July 12, 2014 will be the 30th anniversary of the most expensive hailstorm in the history of Germany, which generated losses around US$2 billion 1984—half of which was insured. The hailstorm developed amid a streak of late afternoon thunderstorms after a day of intense solar heating. A mass of moist sea air flowed into southern Germany overnight and the combination of moisture and rising air triggered a rapidly intensifying thunderstorm system over the Swiss Mittelland that propagated eastward. Hail fell within a 250-kilometer (150-mile) long and 5–15 kilometer (3–9 mile) wide swath from Lake Constance to eastern Bavaria near the Austrian border. At around 8 p.m. local time, the hailstorm passed over Munich, damaging approximately 70,000 houses, 200,000 cars, 150 aircraft, and most agricultural crops within the storm’s path. More than 400 people were injured. Over half of the insured losses were attributed to damaged cars.

July also marks the first anniversary of the 2013 German hailstorm, which caused insured losses of US$3.4 billion, the second highest from a single natural catastrophe in 2013. Like the June 2014 events, the storm hit after a prolonged period of above-average temperatures in central Europe. The first hail event hit northern Germany on July 27, and the second dropped hailstones with a diameter of up to 8 cm (3.1 in) over south Germany the next day.

Interestingly, all these major events occurred in regions with very high potential of hail damage, which can be described in catastrophe models such as the RMS HailCalc model in terms of kinetic energy to help better manage hail risk. In June, RMS presented the first results of a reconstruction of this hailstorm on at the 1st European Hail Workshop. The paper illustrates how a fast estimation of insured hail losses could be obtained following an event in the future. Developing methods of estimating insured loss totals and return periods immediately after an event are an ongoing area of research in the insurance industry, as illustrated in the RMS paper and others at the workshop.

Hailstorm Image Map

 

RMS and Risky Business: Modeling Climate Change Risk

Earlier this year, RMS partnered with the Risky Business Initiative, a year-long effort co-chaired by former New York City Mayor Michael Bloomberg, former Treasury Secretary Henry Paulson, and Farallon Capital founder Tom Steyer to quantify and publicize the economic risks the United States faces from the impacts of a changing climate.

The report, which launched today, has been widely covered in publications ranging from Fortune and The Wall Street Journal to The Hill. It builds on the best available scientific evidence, including both the Intergovernmental Panel on Climate Change (IPCC) and National Climate Assessments, to highlight the risks and cost a changing climate will bring to the business and financial communities the report addresses.

The report details the impact of climate change at the county, state, and regional level; it is the highly vulnerable coastal regions exposed to rising sea levels and the potential for changes in storm activity where RMS has been privileged to contribute our expertise and modeling.

RMS North Atlantic hurricane and storm surge models are based on a base climatology defined by the historical record of storms and represents the current state of the climate. Sea-level rise will increase the risks associated with storm surges and a changed climate may lead to changes in the frequency and intensity of hurricanes the impact the U.S. East Coast and Gulf States.

To address the potential impacts of such changes, RMS pulled together a cross-functional team from our model development group and consulting teams to implement the changes in storm frequency and sea-level rise in our model and analyze the impacts against our database of U.S. property exposure. The team worked with leading climate and hurricane experts and the Risky Business team to understand the latest scientific thinking and gather the information needed to adjust our model from the peer review literature.

In the space of just a few months, the team developed nearly 20 versions of our storm surge hazard model to reflect the expected increase in sea-level rise through the coming decades up to the year 2100, as well as the range of uncertainty captured by the latest IPCC assessment. In addition, the team developed several hundred alternative scenarios of hurricane frequency to model how hurricane frequency may evolve with different “Representative Concentration Pathways” used by the IPCC to describe possible climate futures, possible depending on how much greenhouse gas is emitted in the years to come.

The results of RMS’ analysis, quantifying the changes in losses to hurricanes and storm surges through the coming century have been fed into the Risky Business econometric modeling to quantify the cost to the U.S. economy.

Our analysis highlights that the sea-level rise alone – one of the most certain aspects of a warmer climate – has the potential to more than double the economic losses to hurricanes and storm surges by the end of the century if left unchecked.

RMS, along with Risky Business, recognizes that the analysis is not definitive; however, the potential costs can be quantified and the risks of in-action assessed. This collaboration has developed an invaluable database of information on the impacts climate change on hurricane risk, and by extension, the U.S. economy as a whole.

Just as the Risky Business Initiative hopes to promote a non-partisan discussion on the risks of climate change within the business and financial communities as a whole, RMS hopes that this work and our continued collaboration with the scientific community will lead to continued dialogue in the (re)insurance and catastrophe loss modeling community on the impact of climate change to our business.

Visit http://riskybusiness.org/ to view the full report.

Lessons Learned from Winter Windstorm Season in Europe

The 2013–2014 winter windstorm season in Europe will be remembered for being particularly active, bringing persistent unsettled weather to the region, and with it some exceptional meteorological features. The insurance industry will have much to learn from this winter.

Past extreme windstorms, such as Daria, Herta, Vivian, and Wiebke in 1990, each caused significant losses in Europe. In contrast, the individual storms of 2013–2014 caused relatively low levels of loss. While not extreme on a single-event basis, the accumulated activity and loss across the season was notable, primarily due to the specific characteristics of the jet stream.

A stronger-than-usual jet stream off the U.S. Eastern Seaboard was caused by very cold polar air over Canada and warmer-than-normal sea-surface temperatures in the sub-tropical West Atlantic and Caribbean Sea. Subsequently, this jet stream significantly weakened over the East Atlantic.

Therefore, the majority of systems were mature and wet when they reached Europe. These storms, while associated with steep pressure gradients, brought only moderate peak gust wind speeds onshore, mainly to the U.K. and Ireland. In contrast, the storms that hit Europe in 1990 were mostly still in their development phase under a strong jet stream as they passed over the continent.

The 2013––2014 storms were also very wet, and many parts of the U.K. experienced record-breaking rainfall resulting in significant inland flooding. Again, individual storms were not uniquely severe, but the impact was cumulative, especially as the soil progressively saturated.

Not all events this winter season weakened before impact. Windstorms Christian and Xaver were exceptions, only becoming mature storms after crossing the British Isles into the North Sea and were more damaging.

Christian impacted Germany, Denmark, and Sweden with strong winds. RMS engineers visited the region and observed that the majority of building damage was dominated by the usual tile uplift along the edges of the buildings. Fallen trees were observed, but in most cases, there was sufficient clearance to prevent them from causing building damage.

Xaver brought a significant storm surge to northern Europe, although coastal defenses mostly withstood the storm. Xaver, as well as some of this year’s other events, demonstrated the importance of understanding tides when assessing surge hazard as many events coincided with some of the highest tides of the year. The size of a storm-induced surge is much smaller than the local tidal range; consequently, if these events had occurred a few days earlier or later, the astronomical tide would have been reduced, significantly reducing the high water level.

Windstorm3

Wind, flood, and coastal surge are three components of this variable peril that can make the difference between unsettled and extreme weather. This highlights the importance of modeling the complete life cycle of windstorms, the background climate, and antecedent conditions to fully understand the potential hazard.

This season has also raised questions about the variability of windstorm activity in Europe, how much we understand this variability, and what we can do to better understand it in the future. While this winter season was active, we have been in a lull of storm activity for about 20 years.

Given the uncertainty that surrounds our ability to predict the future of this damaging peril, perhaps for now we are best positioned to learn lessons from the past. This past winter provided a unique opportunity, compared to the more extreme events that have dominated the recent historical record.

RMS has prepared a detailed report on the 2013–2014 Europe windstorm season, which analyzes the events that occurred and their insurance and modeling considerations. To access the full report, visit RMS publications.

2014 Atlantic Hurricane Season Outlook: Are the Tides Beginning to Turn?

The 2014 Atlantic Hurricane Season officially kicked off this week (June 1), running through November 30. Coming off a hurricane season with the lowest number of hurricanes in the Atlantic Basin since 1983, will 2014 follow suit as a less active season? If so, is the Atlantic Basin officially signaling a shift out of an active phase of hurricane activity? Or will we revert back to the above-average hurricane numbers and intensities we’ve grown accustomed to over most of the last 20 years? And regardless of the season’s severity, what should be done to prepare?

Forecasting the 2014 Hurricane Season

Most forecasts to date, including those of Colorado State University and the National Oceanic and Atmospheric Administration (NOAA), are calling for an average to below-average season in terms of the number of named storms (8–13), hurricanes (3–6), and major hurricanes (0–3). The same holds true for the overall intensity forecasts, where projected seasonal values of Accumulated Cyclone Energy (ACE) range from just 55 to 84, compared to the average overall seasonal ACE of 101.8.

So what’s driving this outlook? Most forecasting organizations are attributing it to two major atmospheric drivers that have been known to suppress hurricane activity: the strong likelihood of an El Niño event developing this summer into the peak part of the season from July through October, and below-average sea surface temperatures in the Atlantic Basin’s Main Development Region (MDR).

Model forecasts for El Niño/La Niña conditions in 2014. El Niño and La Niña conditions occur when sea surface temperatures in the equatorial central Pacific are 0.5°C warmer than average and 0.5°C cooler than average, respectively.

Model forecasts for El Niño/La Niña conditions in 2014. El Niño and La Niña conditions occur when sea surface temperatures in the equatorial central Pacific are 0.5°C warmer than average and 0.5°C cooler than average, respectively.

El Niño conditions create stronger-than-normal upper-level winds, which inhibit storms from forming and maintaining a favorable structure for intensification. Similarly, below-average ocean temperatures in the MDR essentially reduce the energy available to fuel storms, making it difficult for them to develop and intensify.

However, low activity does not always translate into a decrease in landfalling hurricanes. Also, all it takes is one landfalling event to cause catastrophic losses. For example, 1992 was a strong El Niño year, yet Hurricane Andrew made landfall in Florida as a Category 5 storm, eventually becoming the fourth most intense U.S. landfalling hurricane recorded, and the fourth costliest U.S. Atlantic hurricane. Of course, while a landfalling storm like Andrew may have occurred during the last significant El Niño year, there’s no guarantee it will happen this season. The U.S. has not experienced a major landfalling hurricane since Hurricane Wilma in August of 2005. This eight-year drought is the longest in recorded U.S. history.

Preparing for Hurricane Season

Whether or not the 2014 Atlantic hurricane season is active, it is imperative to monitor and prepare for impending storms effectively to help reduce the effects of a hurricane disaster.

The NOAA National Hurricane Center provides several tips and educational guides for improving hurricane awareness, including forecasting tools that assess the potential impacts of landfalling hurricanes. This year, NOAA also offers an experimental mapping tool, as well as other new tools, to help communities understand their potential storm surge flood threat.

The RMS Event Response team provides real-time updates for all Atlantic hurricanes, among other global hazards, 24 hours a day, seven days a week. Similarly, when it comes to preparation, along with the essentials, such as bottled water, canned foods, and battery-powered flashlights, consider purchasing these ten items.

Are you ready for the 2014 Atlantic Hurricane season?

Understanding the Potential Impact of the Next Catastrophic European Flood

Over the past year, Europe has intermittently but consistently suffered from significant flooding.

Most recently, the Balkans experienced widespread devastation in May due to some of the region’s heaviest precipitation on record. Three months worth of rain fell in just three days. The subsequent flooding was so severe that entire towns were submerged. While it is too soon to estimate the full impact, the economic and humanitarian costs will be high.

This event follows one of the stormiest and wettest winters on record for the U.K. Remote locations bore the worst of it, and for now, the U.K. government and insurance industry appear to have largely escaped a sizeable bill, at least on the scale of previous flood events.

The events come just one year after the costliest natural catastrophe of 2013 for the insurance industry, when flooding inundated Central and Eastern Europe in late May and early June. The event caused around $20 billion (€12 billion) in economic losses, of which it is estimated that approximately 20 percent was insured.

As with the more recent Balkans and U.K. events, the May 2013 flooding followed a period of extreme rainfall; consequently, groundwater and soil moisture levels were saturated. As more rain fell in late May and early June, the precipitation had nowhere to go except to flow through catchments into the river network as runoff. The Danube, Elbe, and other rivers overflowed, resulting in significant flooding across Germany and the Czech Republic, and, to lesser extents, Austria, Switzerland, Poland, Slovakia, Hungary, Croatia, and Serbia.

Each of these events highlighted the importance of understanding the impact of precipitation, whether from a short, intense period of rainfall, prolonged wet conditions, or a combination of these characteristics. In each case, to evaluate flood risk, it is vital to understand how antecedent wetness conditions influences subsequent flooding.

In 2002, Central Europe was similarly inundated by severe flooding, producing economic losses of over $28 billion (€17 billion). Both events were triggered by similar meteorological phenomena, Genoa type-lows. However, the antecedent conditions in 2002 were comparatively dry compared to those in 2013, and the precipitation that triggered the eventual flooding was more severe in 2002 compared to 2013.

Both events had significant impacts, but what would happen if we combined the worst features of both to create a “perfect storm” type of flood event?

Combining the antecedent wetness of spring 2013 with the extreme precipitation of the August 2002 event, RMS researchers estimated how severe this “perfect flood” could be. Results of this study show a substantial increase in peak flow (more than 50 percent on average) for both the Elbe and Danube rivers.

Elbe River flood hazard map for a "perfect flood event," Riesa, Germany

Elbe River flood hazard map for a “perfect flood event,” Riesa, Germany

In certain locations, this scenario would be characterized by a flood extent (shown above for the area surrounding Riesa, Germany) of about 2.5 times that observed in 2002. But given the remarkable non-linearity between hazard and damage, RMS research estimates that the increased losses could aggregate to a total economic loss of approximately four times the 2002 losses. While this is a theoretical scenario, it is also an entirely realistic one.

The events that have occurred since May 2013 are a stark reminder that flood is a peril from which much can be lost.

After the 2002 flooding, flood defenses were improved in some locations, such as Prague, resulting in less severe flooding. However, because both the flood hazard itself and the physical environment change over time, Europe’s flood risk must be continually and holistically assessed to ensure that we are prepared for when, not if, a similar event occurs again.