Posts

DISASTER 101 – FLOODING

When most people think of natural disasters, the first thing to come to mind is not likely flooding. However, flooding is the most common natural disaster. Flooding occurs in all 50 states, accounts for 40% of natural disasters, averages 5 billion dollars in damage each year, and claimed an average of 75 lives per year over the last 30 years.

Worldwide, statistics are similar.

According to the 30 year average, flooding is responsible for the most weather-related fatalities.

TYPES OF FLOODING

River and Lake Flooding

River and lake flooding is probably what most people envision when they think of floods. Heavy rainfall or snowmelt can cause water levels to rise overflowing banks and levees. River flooding is common in the Midwest as rain and snowmelt swells the tributaries that feed into larger rivers downstream. Once the water level crests the river banks, the area that is inundated can be widespread. Low lying areas, saturated soils, and urban areas can further exacerbate the effects of the overflow and take days to dissipate.

California experienced flooding in February when a weekend of storms increased runoff from Anderson Lake and flooded low-lying areas of San Jose. The early year storms also prompted the evacuation of over 88,000 people near the weakened Oroville Dam.

In May of 2017, heavy rainfall over the Midwest caused widespread flooding. Nearly 15 inches of rain fell over multiple states, saturating soils, and swelling multiple rivers above historic levels. Numerous levees were breached which flooded towns causing an estimated $1.7 billion dollars in damages to homes, businesses, and infrastructure.

40% of all natural disasters are flooding.

Coast Guard overflight of South Carolina flooding

Coastal Flooding and Storm Surge

A form of flooding happens regularly along coastlines due to the cycle of rising and lowering tides. Tides are a regular rise and fall of sea level caused by the gravitational interplay of the sun, moon, and earth. Occasionally, these tides can be exceptionally high. An increase of just a few feet is more than enough for tides to breech natural and man-made barriers. Many coastal cities are very near, or in some cases lower than, sea level making them especially prone to any change in sea level.

Storm surge can also cause extreme coastal flooding. The surge develops during severe weather, hurricanes, and tropical storms raising sea level as much as 25 feet. Sea level rise is the result of the low atmospheric pressure found in these storms which has a similar effect on sea level rise as the gravitational pull on tides. High winds common with these storms also cause large waves to batter the coast and push water farther inland. In worst case scenarios, the storm surge strikes the coast during a high tide cycle, increasing the flooding exponentially. Storm surge flooding is responsible for 90% of hurricane related deaths and the majority of the damage to structures.

In August of 2017, Hurricane Harvey alone caused over $125 billion dollars in damage and killed 89 people. The majority of the devastation caused by Harvey was a direct result of the widespread flooding of the Houston area.

Flash Floods

Flash floods can result from a variety of causes, but the common denominator is that they develop quickly and are normally caused by heavy rainfall. These floods can also be the result of snow melt, dislodged ice, inadequate urban drainage, or dam breaks. The actual volume of water carried in a flash flood is usually less than other flood types but the water is channeled down confined spaces which causes it to move with devastating force and speed. Because of this speed, flash floods are very dangerous, easily carrying mud, rocks, and trees in its flow. A Weather Channel article stated that, “water flowing at 7 mph has the equivalent force per unit area as air blowing at EF-5 tornado wind speed.” Whereas, “water moving at 25 mph has the pressure equivalent of wind blowing at 790 mph, faster than the speed of sound.”

 

BASIC SAFETY AND PREPAREDNESS

Ready.gov provides many helpful tips.

Be Mindful

  • Stay tuned to phone alerts, TV, or radio for weather updates, emergency instructions, or evacuation orders.
  • Avoid walking or driving through flood waters. 6 inches of moving water can knock a person over, and one foot of moving water can sweep a vehicle away. According to the Environmental Protection Agency, the leading cause of flood-related injury and death is individuals attempting to drive through flood waters.
  • Do not drive over bridges that are over fast-moving floodwaters. Floodwaters can scour foundation material from around the footings and make the bridge unstable.
  • If there is a chance of flash flooding, move immediately to higher ground.

Protect your home

  • Know your flood risk, avoid building in flood plains, and consider buying flood insurance.
  • If you have to evacuate due to flooding, and if safety permits, turn off all the utilities to your home and attempt to move valuables to the highest possible level.

SOURCES

https://www.ready.gov/floods
https://www.nssl.noaa.gov/education/svrwx101/floods/types/
https://www.ncdc.noaa.gov/billions/events/US/2017-2018
http://www.floodsite.net/juniorfloodsite/html/en/student/thingstoknow/hydrology/floodtypes.html
https://weatherology.com/articles/106/The+Dangers+of+Flash+Floods.html
https://weather.com/storms/severe/news/power-flood-water-20130704
https://www.livescience.com/23913-flood-facts.html

hurricane harvey spins in gulf

Hurricanes Harvey and Irma batter Southern US

Hurricane Harvey (August 26-31st)

On August 17th,  the National Hurricane Center identified Tropical Storm (TS) Harvey just before it passed through the Lesser Antilles, the islands that form the eastern boundary of the Caribbean Sea with the Atlantic Ocean. Over the next two days TS Harvey moved swiftly to the west into the Caribbean under the influence of an expansive ridge of high pressure but the storm began to rapidly lose energy on the 19th of August and was subsequently downgraded to a tropical depression (TD). As TD Harvey moved from the northwestern Caribbean Sea into the Gulf of Mexico over the next four days it gained strength and was upgraded again to a Tropical Storm (TS). By the 24th of August TS Harvey had rapidly intensified in the Gulf of Mexico and was upgraded to a Category 3 Hurricane. Hurricane Harvey made landfall in the early morning of 26 August in Rockport, Texas as a Category 4 Hurricane with a reported 130 mph maximum sustained winds. Harvey’s center of circulation stalled over South Texas for four days dumping 40 and even 50 inches of rain in the Houston and Beaumont areas. The storm moved slowly east back into the Gulf of Mexico before making a final landfall near Cameron, Louisiana, on August 30th and finally dissipating to the north in the days following.

Harvey’s slow movement from 26-30 August resulted in catastrophic flooding in southeast Texas. Numerous flash flood emergencies were issued for the Houston and Beaumont metropolitan areas as well as Bastrop County and nearby communities. Wind gusts from Harvey exceeded 100 mph in many locations, leading to widespread destruction of homes and buildings. Thousands of homes were affected by Harvey, including over 9,000 that were completely destroyed and more than 185,000 that sustained damage according to the Texas Department of Public Safety. Close to 700 businesses were also reported as damaged. Throughout Texas, more than 300,000 people were left without electricity and as of September 6th, at least 70 deaths have been confirmed as a result of Hurricane Harvey.

Additional Info:

NHC NOAA Harvey Event History

Fox News Harvey Article

 

harvey gif

Hurricane Harvey hangs over coastal Texas from August 23rd to September 1st


Hurricane Irma (September 3-11th)

Hurricane Irma reached the United States Sunday Morning, making landfall in the Lower Florida Keys as a Category 4 Hurricane. A few hours later, Category 3, it made landfall a second time just south of Naples, FL on the Southeast coast of Florida. Due to the extreme size and major hurricane status, most of Southern Florida was warned to evacuate ahead of the storm late last week. Upon landfall, extreme winds battered both southern coasts as wind speeds were recorded at 142 mph in Naples and 99 mph in Miami Beach. Storm Surge from the large powerful storm was reported in many places near ten feet along both coasts affected. On Monday, Irma brought heavy rain and wind through the northern Florida city of Jacksonville where 350 people were rescued from the flooding. Irma also pummeled the Charleston area on Monday with over 8 inches of rain and a nearly 10-foot storm surge. The past 48 hours, evacuated Floridians are again dealing with bumper-to-bumper traffic heading home to face monumental cleanups throughout the state.

Wednesday the 13th, the storm has finally completely broken up, and the National Hurricane Center has stopped updating their reports on the storm. In the wake of the storm, President Donald Trump announced this afternoon that he is set to travel to Florida on Thursday. Moody’s estimates Irma caused $83 billion in damage and 77 deaths have been attributed to the storm. Florida utilities have made good progress in restoring power to communities, as 60% of power has been restored, but 4.6 million people are still without power. It could be months before power is restored to some of the islands that were devastated by the storm.

Florida Keys:

The Florida Keys were the hardest hit and today is the first day that the roads were cleared for people to return to their homes for most of the keys. All 42 bridges along US 1 have been inspected and cleared by the Florida Department of Transportation. 80% of the roads across the keys are cleared. Power is restored to 30% of residents, but over 300 major power lines remain downed. Unofficial estimates from FEMA, according to an ABC News report, state that 25% of homes in the keys were destroyed and 90% had damage of some kind. Big Pine Key and Cudjo Key were hit the hardest, as the storm was still a category 4 when it hit them. Few people have returned to those keys, and most utility services are still unavailable. Fuel remains an issue, especially in the areas without power. Most hospitals remain closed, but some with power or backup power have reopened their emergency rooms. Key West was initially thought to have suffered heavy damage, but once people started returning and assessing the damage, most structures were not impacted, just lots of debris and downed trees.

Additional Info:

NHC NOAA Irma Event History

ABC Irma Update

irma gif

Hurricane Irma moves into and through the Caribbean from Sep 3rd through the 11th

Sources:

National Hurricane Center, NOAA, NASA Worldview

http://www.chicagotribune.com/news/nationworld/ct-hurricane-harvey-flooding-houston-20170829-story.html
https://www.theguardian.com/us-news/2017/aug/26/texas-cities-catastrophic-flooding-hurricane-harvey
https://www.theguardian.com/us-news/2017/sep/01/hurricane-harvey-death-toll-rises-houston-residents-return
https://weather.com/storms/hurricane/news/tropical-storm-harvey-forecast-texas-louisiana-arkansas
http://www.nhc.noaa.gov/archive/2017/al09/al092017.update.08241656.shtml

GOES-R Environmental Satellite Launched

On November 19, NASA celebrated the successful launch of its latest weather satellite, the revolutionary GOES-R (named GOES-16 once it is operational). This next generation Geostationary Operational Environmental Satellite (GOES) will deliver better weather forecasting, severe storm tracking, and space weather monitoring for Earth’s entire western hemisphere.

GOES-R Liftoff on November 19, 2016

GOES-R Liftoff on November 19

GOES-R_Spacecraft

GOES Mission Overview

Positioned roughly 22,000 miles above Earth’s surface, GOES satellites continuously monitor the Western hemisphere, including the United States, the Pacific and Atlantic oceans, Central and South America, and Southern Canada. GOES satellites fly in a geostationary orbit, meaning they rotate around the Earth at the same rate as the Earth spins, so their view of the Earth’s surface never changes. The coverage, along with the sensor suite, allows for constant, near real time coverage of Earth’s weather, climate, and large storm events. GOES also has sensors looking toward the sun and space, measuring solar and space weather.

Why the GOES-R Satellite is Significant

The most exciting update to GOES-R in relation to disaster intelligence is the updated Advanced Baseline Imager (ABI). The image above describes the improvements to the new sensor. Below are the benefits related to these improvements.

  • Improved hurricane track and intensity forecasts
  • Improved route planning for aviation
  • More advanced warning for severe storms
  • More advanced warning for air quality warnings and alerts
  • Better fire detection and intensity estimation
  • More and better quality data for long-term climate variability studies

This is only one of several next-generation advanced sensors onboard GOES-R. Other sensors will help researchers study tornado warnings, climate, and space and solar weather. It’s no wonder that people are excited about this momentous launch!

Source(s):

http://www.goes-r.gov/

https://www.nesdis.noaa.gov/content/6-reasons-why-noaa%E2%80%99s-goes-r-satellite-matters

Hurricane Matthew Brings Dangerous Conditions to the Coast

Hurricane Matthew Update:  October 7, 2016.

Hurricane Matthew continues to push north paralleling the east coast of Florida.  The storm has yet to make landfall, but powerful wind gusts of over 100 mph have downed trees and caused power outages for nearly 1,000,000 people.  Bands of heavy rain currently stretch as far north as South Carolina with flash flooding likely across the lowland areas.  The hurricane has been reduced to a category 2 storm, staying just offshore, but the threat of storm surge flooding remains a critical concern.

Hurricane Matthew

Hurricane Matthew predicted path, as shown in the RZAlert Dashboard.

Unease Growing Over Storm Surge

The storm is currently off the northeast coast of Florida, dousing the coastal town of Jacksonville.  Storm surge flooding combined with heavy rain has already effected much of northeast Florida and Georgia, with–maybe–the worst conditions  yet to come.

In St. Augustine (FL), flooding preceded the storm inundating much of the city’s historic downtown with knee-deep water.  The storm surge in St. Augustine is projected to top 8 feet in some places as the water continues to rise. Nearby, the city of Jacksonville fears for an unprecedented event, warning residents of the potential for catastrophic damage. Officials are expecting storm surges as high as 9 feet and residents began evacuating days ago. According to the city’s mayor, anything over 3 feet is life-threatening.  A major tropical storm has not impacted the city of Jacksonville in over a century.

Charleston Susceptible

Fears are also mounting for the Charleston area where the eye-wall is projected to potentially center itself over the Coastal Carolina city come Saturday morning. Officials are worried the flood levels could be near or even surpass those experienced in the October 2015 flood event which set historic records in terms of damage and lives lost.  The nowCoast™ modeling of the potential storm surge by the National Oceanic and Atmospheric Administration shows dangerous conditions far inland due to the numerous inlets and intercostal waterways. Interestingly, the storm is projected to move clockwise away from the Southeastern US coast and curl back around toward Cuba. Time will tell what else this storm has in store for an area that has historically escaped major hurricane impact.

Hurricane

Storm surge forecast for Charleston, NC.

Sources:

http://www.pbs.org/newshour/rundown/heres-hurricane-matthew-might-cause-worst-flooding/?utm_content=buffer1cf9c&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

https://weather.com/storms/hurricane/news/hurricane-matthew-bahamas-florida-georgia-carolinas-forecast

https://weather.com/news/news/south-carolina-historic-flood-rainfall-record-extreme

http://www.cnn.com/2016/10/07/us/hurricane-matthew-florida/