Tag Archives: WRN

Sandy Highlights the Dangers of Rising Sea Levels

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Six months ago today, Super-storm Sandy devastated a large section of the northeastern United States.  The flooding caused by its record storm surge was a heart-wrenching example of the dangers posed by rising sea levels.

Storm surge is the rise in sea height that occurs during an intense storm like a hurricane or nor’easter. Its baseline is local sea level. So, as sea levels rise, storm surges are able to reach further inland.  This is a serious problem for coastal communities around the world.

According to climate scientists, the average global sea level has risen about eight inches since 1880.  This may not sound like a lot, but it is a significant amount when you consider it is spread out across all of the world’s oceans.  That said, sea levels are not rising evenly across the planet.  Recent studies have found that certain areas, such as the East Coast of the US, are experiencing faster rates of sea level rise than others.  New York Harbor, for example, has seen its water level increase by more than a foot in the past century.

Sea level rise has two main drivers. They are thermal expansion – a process in which water expands as it warms – and the melting of massive amounts of land based ice, such as glaciers and ice sheets.  Both are the result of rising global temperatures.

In the future, sea levels are expected to continue rising as our atmosphere warms. Estimates of how much vary from four inches to two feet above current levels by 2050. This wide range reflects uncertainty in the amount of future greenhouse gas emissions, subsequent warming, and rate of ice melt.  What is certain, however, is that the frequency and magnitude of storm surge flooding will increase as sea levels rise.

Preparing for Hurricane Sandy

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Hurricane Sandy, the 18th named storm of this Atlantic hurricane season, battered the Caribbean earlier this week.  Now, it is on course to make landfall along the northeastern coast of the United States within the next few days.

Forecasters, at this point, are uncertain of the exact track the storm will take, but expect it to be a long duration and high impact event. They anticipate that Sandy will bring high winds, heavy rain, coastal storm surges, and flooding to this country’s most densely populated region.  These weather hazards are, in turn, likely to cause widespread power outages.

To prepare, emergency officials suggests:

  • Monitor the news for the latest storm information and any evacuation orders
  • Prepare a storm emergency kit with:
    • Water
    • Non-perishable food
    • Flashlights
    • Battery-powered or hand-crank radio
    • First aid kit
    • Cash
    • Filled prescriptions
    • Extra batteries

For more details on storm preparedness, visit the websites of FEMA and the American Red Cross.

How Droughts Work

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The drought of 2012 has gone from bad to worse this summer as relentlessly hot and dry conditions continue to dominate the central United States.

Once drought takes hold of a region, it tends to feed on itself in a vicious cycle. To start, high temperatures increase evaporation rates causing the soil to dry out.  Without plentiful rain to replace the moisture, the sun’s energy heats the ground and the air even further.  The parched ground is then unable to support healthy vegetation that would release moisture into the air through transpiration.  Humidity levels then drop and the air becomes even less able to produce rain, making the affected area even drier.

To break this cycle, a drought stricken region needs more than a few spotty showers. It requires drenching rains on a regular basis.  Alas, these are not in the forecast for America’s desiccated heartland.

Image Credit: Agriculture Emergency Report

Drought Economics

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The widespread drought of 2012 is now considered the worst that the United States has seen in more than fifty years. The nation’s agricultural heartland has been particularly hard hit, and losses there are forecast to have a ripple effect throughout the economy.

According to the U.S. Department of Agriculture, 1,297 counties in 29 states have been designated as natural disaster areas. With grazing lands going barren and staple crops like corn and soybeans wilting in the ground, potential farm yields are plummeting. Following the laws of supply and demand, consumers all across the country will soon be paying higher prices for food.

The cost of many other goods is also expected to rise, as corn is used in a wide variety of products.  It is a key ingredient in items like livestock-feed, ethanol, and anything that contains corn syrup.

Devastating and costly, this drought is likely to intensify as hot and dry conditions continue to dominate the weather in the mid-west.  While not on the same scale as the Dust Bowl of the Great Depression, many analysts expect this year’s drought to rank as a billion dollar natural disaster.

Corn crop withers in drought stricken field.

Image Credit: BuffaloNews

Western Wildfires and Climate Change

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Summer is wildfire season in the American West, and it is off to a raging start. Fueled by prolonged drought and extreme heat, many experts agree that climate change is a significant contributing factor to this year’s widespread fires.

According to NOAA, the past eleven years have all ranked among the warmest on record in terms of global average temperatures. This warming trend, scientists report, is causing an increase in both the frequency and intensity of many dangerous weather phenomena, including forest fires.

This year, hot and dry conditions have dominated much of the United States.  In fact, this summer’s excessive heat follows our country’s warmest spring ever and fourth warmest winter to date.  In the West, these unusually mild conditions did not allow a sizeable snow pack to accumulate in the mountains, reducing spring run-off.  As a result, the region is parched and susceptible to any type of spark.

Warmer winters have also allowed the Rocky Mountain Pine Beetle population to explode and spread to higher elevations.  Feeding on various types of pines, the beetles leave large stands of dead trees in their wake when they move through an area. These ghost forests then essentially act as kindling for potential wildfires.

As of today, nearly forty large fires are burning in ten western states. Despite the arrival of the region’s monsoon season, many of these destructive flames are expected to continue blazing throughout the summer.

Intense wildfires burn across the American West.

Image Credit: KSTP

Weather and Health: Extreme Heat

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An oppressive heat wave is currently scorching the central region of the United States and is forecast to expand eastward this weekend.  As temperatures soar, it is important to remember that intense heat can cause serious health problems.

According to the CDC, extreme heat – temperatures that are significantly hotter than the average local summertime high – is one of the leading causes of weather related deaths in this country.   Claiming hundreds of lives every year, excessive heat kills more people across the U.S. than hurricanes, tornadoes, floods, and earthquakes combined.

Extreme heat is deadly, because it forces the human body beyond its capacity to cool itself. Linked to overheating and dehydration, heat related illnesses range in severity from mild to life threatening.  Symptoms for each stage include:

Heat Cramps:  painful muscle spasms in the legs and/or abdomen

Heat Exhaustion:  fatigue, weakness, clammy skin, and nausea

Heat Stroke:  rapid pulse, hot and dry skin, no sweating, victim could possibly be
unconscious;  a medical emergency

To beat the heat, the American Red Cross suggests:

  • Avoid strenuous activity
  • Dress lightly
  • Eat lightly
  • Drink plenty of water
  • Replenish salts and minerals lost to perspiration
  • Limit caffeine and alcohol
  • Stay out of the sun
  • Cool off in an air-conditioned building, when possible

The Saffir-Simpson Scale for Rating Hurricanes

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Hurricanes are one of nature’s most powerful storms. When formed in the Atlantic Ocean or North-Eastern Pacific, they are rated according to the Saffir-Simpson Scale.

Developed in the early 1970’s by Herbert Saffir, a civil engineer, and Dr. Robert Simpson of the National Hurricane Center, the scale classifies hurricanes into five categories based on the strength of their sustained winds.  Each category is considered an estimate of the potential damage that a storm will cause if it makes landfall.  As conditions change within a storm, its category is re-assessed.

The different categories, 1 through 5, represent increasing wind speeds and escalating degrees of damage.  Since its introduction, the NHC has modified the Saffir-Simpson Scale a number of times.   In fact, earlier this year they refined the wind speed range for categories three through five.  These changes are reflected in the chart below.

Chart Source: NOAA

How Hurricanes Form

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Hurricanes, named after the ancient Mayan god of wind, are known as the greatest storms on Earth. Referred to as typhoons or simply cyclones in other parts of the world, they develop under different conditions than an average storm.

Producing powerful winds and heavy rain, hurricanes are mature tropical cyclones that have progressed through a number of stages.  Defined by wind speed, these stages include:

  • Tropical Depression: wind speed of 38 mph or less
  • Tropical Storm: winds range from 39-73 mph
  • Hurricane: winds of 74 mph and above

Regardless of their ultimate size or intensity, all tropical cyclones start off as a tropical disturbance – an unorganized cluster of thunderstorms – over a large body of warm water.  These convective storms generate a column of rising air and an area of low pressure. As moisture-laden tropical air sweeps in to fill the low-pressure void, the storm grows and its winds strengthen. Rising upward, the incoming humid air cools and causes water to condense which releases huge amounts of latent heat. This newly freed heat causes air to rise up even further, producing more condensation and extracting additional heat. Through this process the storm system is able to continuously fuel itself.

Subject to the Coriolis Effect, a mature tropical cyclone is essentially a spinning collection of thunderstorms. Once designated as a hurricane, the storm is ranked on the Saffir-Simpson Scale according to its wind speed. A hurricane’s strongest winds are found in the eye wall, the area that surrounds the storm’s calm eye and point of lowest pressure.

Numerous tropical disturbances develop every year, but only a few grow into full-blown hurricanes. According to NOAA, an average of six hurricanes develop in the Atlantic Ocean annually.

NOAA satellite image of Hurricane Daniel (2006)

Image Credit: NOAA

How Tornadoes Form

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Generated by severe thunderstorm activity, tornadoes are nature’s most violent storms. Scientists do not know exactly what causes them, but atmospheric instability and wind shear are important contributing factors.

Instability in the atmosphere is created when a warm, humid air mass meets a cool, dry air mass.  Through the process of convection, this encounter allows warm air to rise easily and produce thunderstorms.  The greater the instability, the stronger a thunderstorm can become.

Wind shear occurs when there is a localized change of wind speed and direction.  When surface winds blow in one direction and upper level winds in another, the air in-between is set in a horizontal rolling motion.  The updraft of the thunderstorm can then tilt the rotating air into a vertical position.  When that vortex extends from the cumulonimbus cloud to the ground, a tornado is born.

Tornadoes can occur anywhere in any season, but are more typical in the spring and summer months in the United States.  According to NOAA, approximately 1,200 tornadoes touch down in this country every year.

Severe Weather: Watches and Warnings

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Severe weather can happen anytime of the year, given the proper conditions.  This past weekend, for example, unstable air and wind shear combined to send tornadoes roaring through America’s heartland.

Any meteorological event that can cause property damage and loss of life is categorized as severe. It can come in a variety of forms, depending on location and season.  High winds, strong thunderstorms, tornadoes, wildfires, dust storms, hurricanes, floods, and blizzards are all examples of severe weather that occurs in the United States.

When any severe weather event is in the forecast, it is important to understand the difference between the various alerts issued by the National Weather Service.  They include advisories, watches, and warnings.  All should be taken seriously.

  • Advisory:  An “advisory” is issued when significant, but not severe, weather conditions are likely to occur. Residents should exercise caution.
  • Watch:  A “watch” is issued when dangerous weather conditions are possible over the next several hours.  They generally cover a large geographic area.  Residents should be prepared to take action.
  • Warning:  A “warning” is issued when dangerous weather is imminent or already occurring.  They cover a smaller, more specific geographic area.  Residents should take action immediately.