Hurricane Nate Slams Gulf Coast

Hurricane Nate, the 14th named storm of the 2017 Atlantic Hurricane season, made two landfalls along the US Gulf Coast this weekend. The first was near the mouth of the Mississippi River in Louisiana and the second was near Biloxi, Mississippi.

Coming ashore with 85mph winds, this category-1 hurricane generated a significant storm surge that swamped parts of the region from Louisiana to the Florida Panhandle. One of the hardest hit areas was Pascagoula, MS where a storm surge of 6.3 feet was reported. The storm also downed trees and caused widespread power outages.

Moving inland, Nate was soon downgraded to a tropical depression. However, it still spawned a number of destructive tornados from Alabama to North Carolina. They ranged in strength from EF-0 to EF-2.

Nate was the first hurricane to make landfall in Mississippi since Katrina in 2005.

Credit: NOAA/NASA GOES

Harvey Unleashes Catastrophic Flooding in Houston

Days after making landfall as a category-4 hurricane, Harvey, now a tropical storm, is still battering southeast Texas. Relentless rain has unleashed catastrophic flooding across the region, including Houston – this country’s fourth largest city.

While this devastating event is still unfolding, rainfall totals in some areas have already exceeded two feet. Dayton, TX, northeast of Houston, has reported a staggering 39.72 inches of rain since Thursday. Houston Intercontinental Airport (IAH) has posted 25.66 inches of rain so far and reported its wettest calendar day on record on Sunday with 16.07 inches.

This intense rainfall is causing the many rivers, creeks, and bayous in the metro Houston area to overflow their banks and flood homes, businesses, and major roadways – effectively paralyzing the area. Rainfall rates reached as high as 3 inches per hour on Sunday in some areas, prompting the NWS to issue a flash flood emergency – the highest level of a flood alert.

No evacuation order was issued ahead of the storm in Houston and residents were told to shelter in place. Now, thousands of high water rescues are taking place via boat and helicopter to save people trapped in their homes. The situation has many people comparing it to scenes that played out in the aftermath of Hurricane Katrina in New Orleans. The mayor of Houston, Sylvester Turner, has opened the massive George R. Brown Convention Center to be used as a shelter. As of Monday, eight storm-related deaths have been reported. But sadly, local authorities expect this number to increase as the water continues to rise.

Southeast Texas is no stranger to flooding. However, officials in Houston say this event is the worst they have seen since Tropical Storm Allison in 2001. That storm dumped more than 35 inches of rain on the metro area over the course of five days and caused $5 billion worth of damage.

Harvey, wedged between two areas of high pressure, is expected to linger over the region for several more days and dump an additional 15 to 25 inches of rain. Forecasters at the NWS say the rainfall total for this storm could reach an unprecedented 50 inches in some spots.

Eighteen counties in Texas, according to Governor Greg Abbot, have been declared federal disaster areas because of this storm.

TS Harvey caused unprecedented flooding in Houston, TX. Credit: Aryan Midas

Hurricane Harvey Hammers Texas

Hurricane Harvey, the eighth named storm of the 2017 Atlantic Hurricane Season, made landfall in Rockport, TX late Friday night. It was the strongest storm to hit the United States in twelve years.

Coming ashore with winds measured up to 130mph, Harvey was classified as a Category-4 hurricane on the Saffir-Simpson Scale. These powerful winds along with storm surge flooding and torrential rain caused catastrophic property damage across the Texas Coastal Bend region. It also downed trees and left hundreds of thousands of people without power. To date, according to local officials, only two storm-related deaths have been reported.

Moving inland, toward Houston, Harvey weakened to a Tropical Storm on Saturday afternoon. However, despite this downgrade in wind speed, its rain bands are still drawing moisture from the Gulf of Mexico and unleashing massive amounts of precipitation. Wedged between two areas of high pressure, the storm is essentially stalled over the region. Therefore, even more flooding rain is expected over the next several days.

Harvey was the first major hurricane – category 3 or higher – to make landfall in the Lone Star State since Hurricane Carla in September 1961.

Satellite imagery from NOAA shows Hurricane Harvey along the Texas Coast. Credit: NOAA

Hurricane Matthew Slams the Southeastern US

Hurricane Matthew, the 13th named storm of the Atlantic Hurricane Season, hammered the southeastern United States this weekend from Florida to Virginia.

Tearing up the coast as it trekked northward, Matthew made landfall near McClellanville, SC on Saturday as a category-1 hurricane with 75mph winds. It had reached category-5 status in the Caribbean – the first storm to do so since Hurricane Felix in 2007- but weakened as it moved toward the US.

Despite this downgrade, Matthew still packed a powerful punch. Its strong winds, flooding rains, and storm surge caused significant property damage and widespread power outages throughout the region. The death toll from this storm currently stands at 26 people from across five states and is expected to increase in the coming days.

With successive bands of heavy rain, Matthew also caused catastrophic inland flooding. In Fayetteville, NC – 100 miles from the coast – 14.82 inches of rain was reported. As a result, several rivers in the region rose to record or near-record levels and overflowed their banks, inundating communities.

All told, Matthew dumped 13.6 trillion gallons of water on Florida, Georgia, South Carolina, North Carolina, and Virginia before heading out to sea as a post-tropical storm. That is enough water to fill over 20 million Olympic-size swimming pools. The highest rainfall total, 17.49 inches, was reported near Savannah, GA.

The damage caused by Matthew is currently estimated at $6 billion.

Hurricane Matthew batters the south eastern US. Credit: NOAA/NASA

Hurricane Matthew batters the southeastern US. Credit: NOAA/NASA

Hurricane Hermine Batters Florida’s Gulf Coast

Hurricane Hermine, the eighth named storm and fourth hurricane of the 2016 Atlantic Hurricane Season, made landfall in the Big Bend region of Florida early Friday morning. It slammed the Sunshine state’s west coast from Tampa to Tallahassee with heavy rain and winds measured up to 80 mph.

The category-1 hurricane generated a 9-foot storm surge in Cedar Key and dumped more than 22 inches of rain in parts of Pinellas County, flooding many communities. The storm also downed trees and knocked out power to over 250,000 people. Only one storm related death was reported.

Traveling across Florida, Hermine was downgraded to a tropical storm. It is now in the Atlantic moving north along the eastern seaboard. Impacts such as powerful winds, heavy rain, coastal flooding, and dangerous rip currents are expected to be felt from Georgia to Connecticut this holiday weekend.

Hermine was the first hurricane to make landfall in Florida in eleven years.

Hurricane Hermine makes landfall in Florida on September 2, 2016. Credit: NOAA

Hurricane Hermine makes landfall in Florida on September 2, 2016. Credit: NOAA

The Thames Barrier Protects London from Flooding

The Thames Barrier protects millions of people and billions of dollars worth of property in greater London from flooding. As a New Yorker who experienced Superstorm Sandy and its record storm surge first hand, I made a point to visit this crucial piece of engineering during a recent trip to the UK.

Completed in 1982 at the cost of £535 million (about £1.6 billion today), the barrier was built in response to the catastrophic North Sea Flood of 1953. Often called the worst natural disaster to hit the UK, the floodwaters claimed the lives of 307 people and caused widespread damage estimated at £50 million (£1.2 billion today).

According to the UK Met Office, the deadly flood was caused by the combination of a high spring tide and an intense extra-tropical storm in the North Sea. Together, they generated a storm surge of 18.4 feet above average sea level. Moving upstream during the overnight hours of January 31, 1953, the high water overwhelmed the existing floodwalls and inundated communities along the Thames Estuary with little or no warning.

Situated downstream of central London, the barrier consists of ten individual steel gates that span a section of the river that is 1700 feet wide. It is the second largest movable flood barrier in the world, after the Oosterscheldekering barrier in the Netherlands. The Netherlands were also hard hit by the 1953 storm, with over 1800 lives lost to floodwaters.

When a storm surge or an exceptionally high tide is expected, all of the individual gates of the Thames Barrier are closed creating a solid steel wall, approximately five stories high, across the river. While this protects London from flooding from the sea, the barrier can also be used to help reduce fluvial flooding caused by heavy rainfall. When a high amount of water is forecast to flow downriver, the barrier is closed just after low tide. This creates a volume of space behind the barrier – sort of like a temporary reservoir – for the extra water coming downstream to fill. Without the barrier, the incoming tide would take up this space and cause the river water to rise even higher and spill out of its banks.

To date, according to the UK Environment Agency, the Barrier has been closed 176 times since it became operational 34 years ago. Of these closings, 89 were to protect against tidal flooding and 87 were to help alleviate fluvial flooding.  At the time it was built, it was only expected to be used 2 to 3 times per year.

Looking ahead, as the climate warms, heavy precipitation events in the UK are expected to increase and sea levels will continue to rise. This means the barrier will most likely be called into action even more often.

While there was debate about the feasibility and cost of building the barrier, as there is with any large government project,  it has repeatedly proven itself to have been a worthwhile investment. It is expected to remain a viable flood defense tool through the 2060’s.

The Thames Barrier protects London from flooding. Credit: Melissa Fleming.

The Thames Barrier protects London from flooding. Credit: Melissa Fleming.

The Flood Forecasting Lions of London

The River Thames is as much a part of London as the buildings and palaces that sit along its banks. During a recent visit to the UK’s capital city, I learned more about this storied river and its long history of flooding.

London is situated along the tideway – the part of the Thames that is subject to tides. As such, it faces a flood threat from exceptionally high tides and powerful storm surges sent up river from the North Sea. Heavy rains that fall west of the city can also send torrents downstream.

Today, the mighty Thames Barrier protects the city against massive deluges, but an older flood warming system is still visible along parts of the river.

These are the bronze lion heads that line both sides of the Thames at Victoria Embankment in central London. Installed in the late 1860’s as part of the Great London Sewage Works project, they are often overlooked today as decorative moorings.

While they do not offer any protection from floods, the lions serve as visual markers for rising water. Basically, if the water level reaches their mouths, the city is at risk of a flood. Or, as the locals like to say, “When the lions drink, London will sink.”

Bronze lion heads line the wall of the River Thames, London.

Bronze lion heads line the wall of the River Thames, London.

Historic Flooding in West Virginia

Relentless rain unleashed catastrophic flooding across West Virginia late last week. Officials say it was the state’s worst flood disaster in more than a century.

According to the NWS, the Mountain State received about 25% of its average annual rainfall in just a few hours. In Greenbrier County, more than 10 inches of rain fell between Thursday and Friday. This massive amount of precipitation in such a short period of time overwhelmed rivers and streams throughout the area. In Kanawha County, which includes the state capital of Charleston, the Elkview River crested at 33.37 feet – its highest crest in more than 125 years of record keeping.

The raging torrents of floodwater damaged or destroyed thousands of homes and businesses, as well as infrastructure across the state. To date, twenty-three weather-related deaths have been reported and more than 10,000 customers are still without power.

This type of rainfall is considered a one in one thousand year event in West Virginia. That does not mean it can only happen once every thousand years. It is the recurrence interval, a statistical calculation that means an event has a one in one thousand chance (0.1%) of happening in any given year in a given location.

The cause of this devastating flooding was twofold and involved a combination of weather and topography. First, “training” thunderstorms developed along a boundary between cooler air to the northeast and warm, moist air to the southeast. This is a meteorological phenomenon where strong storms flow continuously over the same area for a relatively short period of time – like train cars traveling along a track – dumping excessive amounts of rain.

The second major player in this deadly deluge was the state’s mountainous topography. When substantial rain falls in hilly terrain, it runs downslope very quickly and causes flash flooding in valleys, where most people tend to live. Moving with tremendous force, this type of fast flowing water can pick up and destroy almost anything in its path.

The Governor of West Virginia, Earl Ray Tomblin, has declared a state of emergency in 44 of the state’s 55 counties as a result of the flooding. Additionally, President Obama declared a major disaster in three of the hardest hit counties – Kanawha, Greenbrier, and Nicholas – which allows federal funds to supplement state and local emergency efforts.

Flooding In West Virginia. Credit: ABC11

Flooding in Richwood, Nicholas County, West Virginia. Credit: J. Rose/ABC11

Bonnie Makes Landfall as a Tropical Depression in South Carolina

Bonnie, the second named pre-season storm of 2016, made landfall on Sunday just east of Charleston, South Carolina on the Isle of Palms.

According to the NWS, Bonnie was categorized as a tropical storm on Saturday with winds as high as 45mph. But by the time it came ashore, its winds had fallen below 39mph – the threshold for a tropical storm – and was downgraded to a tropical depression. Despite this reduced status, the storm still brought heavy rain, flash flooding, and dangerous rip currents to the area.

Rainfall totals, according to the Charleston NWS office, reached as high as ten inches in some spots. Flash flooding in Jasper County even caused sections of Interstate 95 – one of America’s busiest highways – to close.

Remnants of Bonnie are expected to linger over the southeastern US for the next several days, bringing even more rain to the region.

The Atlantic Hurricane Season official begins on June 1st.

Bonnie makes landfall as a tropical depression near Charleston, SC. Credit: NASA

Bonnie makes landfall as a tropical depression near Charleston, SC. Credit: NASA

 

Historic Flooding in Houston

Relentless rain unleashed catastrophic flooding across southeast Texas on Monday. Local officials say this was the worst flooding event the region has seen in years.

Rainfall totals across the Houston metro area varied, but some places saw nearly 17 inches in less than 24 hours. The NWS office in Houston reported 9.92 inches of rain at Houston Intercontinental Airport (IAH), making it that city’s second wettest day on record. On average, Houston typically gets 3.46 inches of rain for the entire month of April.

The intense rainfall caused bayous to swell out their banks and flood homes, businesses, and major roadways – effectively paralyzing large parts of this country’s 4th largest city. Rainfall rates reached as high as 3 to 4 inches per hour in some spots, which prompted the NWS to issue a flash flood emergency (the highest level of flood alert) for the area. Local officials say 5 people were killed and more than 100,000 people lost power as a result of the flood.

The primary driver behind this extreme rain event was also main reason why the eastern US has been unseasonably warm and dry recently. The omega block that sat over the country for the past few days basically set up a large ridge of high pressure in the east and blocked an upper-level low from moving past the Four Corners region. Essentially stuck in place, the upper-level low funneled in massive amounts of moisture from the Gulf of Mexico. That moisture was then forced to rise and cool when it interacted with the stationary front in the area. The result was an extended period of thunderstorms and intense rainfall.

Southeast Texas is no stranger to flooding. In fact, this was the fourth major flood to hit the area in the past twelve months. The previous three took place in May, June and October of 2015. But, officials in Houston say Monday’s event was the largest flood the area has seen since Tropical Storm Allison in 2001. That storm dumped more than 35 inches of rain on the Houston metro area over the course of five days and caused $5 billion worth of damage.

The Governor of Texas, Greg Abbot, has declared 9 counties to be disaster areas as a result of Monday’s storm.  More rain, unfortunately, is forecast for the region this week.

View of flooding in downtown Houston, TX. Credit: KHOU

View of flooding in downtown Houston, TX.  Credit: KHOU