Hurricane and typhoon watch

There are two major hurricanes in action at the moment – Hurricane Florence weakening as it makes landfall in the eastern US, and Super Typhoon Mangkhut currently bearing down on the Philippines.

Super Typhoon Mangkhut made landfall in the northern Philippines early Saturday with maximum sustained winds of 270 kph (165 mph) and gusts as high as 325 kph (200 mph), which is the equivalent of a Category 5 hurricane.

That’s horrendous. The wind is getting very strong here when it gets in the 120-150 kph range, but Mangkhut is twice that.

 

Al Jazeera:  Super typhoon Mangkhut makes landfall in the Philippines

Monster Typhoon Mangkhut has made landfall in the northeastern tip of the Philippines, affecting at least five million people in its path.

Mangkhut, also known as Ompong in the Philippines, made landfall at around 17:40 GMT on Friday (01:40 am Saturday, local time), according to the Philippine weather bureau, PAGASA.

It retained its ferocious strength on Friday, but gained speed while shifting towards a number of densely populated provinces, where a large evacuation was carried out earlier in the day.

The Hawaii-based Joint Typhoon Warning Center categorised Mangkhunt as a super typhoon with powerful winds and gusts equivalent to a category 5 Atlantic hurricane.

In comparison, Hurricane Florence, which is currently lashing the US East Coast, is classified as category 1 storm.

It is packing winds of up to 205 kilometer per hour and gusts up to 255km/h, PAGASA said. But the US Navy’s Joint Typhoon Warning Center said maximum winds could reach 268km/h and wind gusts of up to about 324km/h.

After it passes the Philippines it will head towards Hong Kong:

In the Us Hurricane Florence wind strengths have eased substantially but widespread flooding and disruption is still expected.

Fox News: Hurricane Florence moving slowly, but ‘wreaking havoc’ across Carolinas

Slow moving and powerful Hurricane Florence is “wreaking havoc” across the Carolinas as the Category 1 storm continues to dump massive amounts of rain that could trigger catastrophic floods inland.

Once a Category 4 hurricane, a weakened but still-dangerous Florence is now making its way south along the Carolina coast at about 6 mph with sustained winds of 80 mph – pushing life-threatening storm surges miles inland, ripping down parts of buildings and knocking out power to more than a half-million homes and businesses early Friday.

The center of Florence made technical landfall at about 7:15 a.m. on Friday near Wrightsville Beach, N.C.

Florence’s storm surge and the prospect of 1 to 3½ feet of rain were considered a bigger threat than its winds, which dropped off from an alarming 140 mph earlier in the week. Forecasters said catastrophic freshwater flooding is expected well inland over the next few days as Florence crawls westward across the Carolinas all weekend.

Forecasters said the terrifying onslaught would last for several hours, because Florence was barely moving along and still drawing energy from the ocean. They said “catastrophic” freshwater flooding was expected along waterways throughout the Carolinas.

“Twenty-four to 36 hours remain of significant threat from heavy rain and heavy surge,” said Jeff Byard, an administrator with the Federal Emergency Management Agency. “Those citizens who did not heed evacuation warnings, it’s time to stay where you are, do the best that you can to protect yourself.”


Weatherwatch: Has NZ ever experienced Cat5 winds?

In 1968 a former tropical cyclone called Giselle was tracking across the North Island.  At the same time a polar storm was racing out of the Southern Ocean.  The two collided over Wellington creating what is known as the “perfect storm”.

It was this storm that sunk the Wahine ferry in Wellington harbour as it blasted the capital with hurricane force winds.  NIWA records show winds gusted to 275km/h – which is equal to a category 5 cyclone.  Around 100 homes lost their roofs.

But the winds were very different to a cat 5 cyclone.  With a cyclone, the strong winds are generated around the eye of the storm over open water.  In this case it was the merger of the two systems and Wellington’s localised topography that created the incredible winds – and they only existed as this strength in one part of Wellington.

It was the first and only time winds of that speed were recorded in New Zealand.

But from a NIWA employee:

The 275 km/h is a reference to a 3-s gust speed from a Munro anemometer located at Oteranga Bay during the storm. I’ve always understood that this reading was highly questionable due to an issue with the anemometer at that site at the time of the storm. I’ve double-checked with Steve Reid (retired employee of NIWA and before 1992 MetService) who was the wind-expert at both institutions for several decades. He had in the past checked the instrument file for Oteranga Bay and noted that the next technical visit to the site after the Wahine storm had remarks that a “substitution resistor was missing from the installation” and this would result in speeds 25% too high.  The resistor was used in installations where no dial was in the circuit. For this reason, the observation is highly questionable at best, and should not really be accepted as a record.  – NIWA

That would make the maximum gust closer to 200 km/h, still very strong but nothing like Mangkhut.

Irma hits Cuba, Florida waits

The latest on hurricanes Irma and Jose and the now storm Katia from the Guardian:

  • Hurricane Irma slowed to a category three storm as it crashed across Cuba’s northern coast, lashing towns with 125mph winds and flooding them with intense surges. As of midday local time, the storm was about 170 miles away from Florida, and expected to regain category four intensity.
  • More than seven million people were ordered to flee from their homes in several states, including nearly a third of Florida’s population. More than 50,000 people are in about 300 shelters around the state, counties enacted curfews, and power providers already began to struggle with demand.
  • Florida prepared for what its governor called “the most catastrophic storm the state has ever seen”. Irma is forecast to make landfall on the Florida Keys early Sunday morning and then to pummel south-west Florida on a 30-hour journey northward.
  • In Florida’s south-west, officials expect storm surges as high as 15ft. “Fifteen feet is devastating and will cover your house,” governor Rick Scott said. “Do not think the storm is over when the wind slows down. The storm surge will rush in and it could kill you.” Large swaths of Florida were given tornado warnings, and the National Weather Service’s Key West station delivered a dire warning: “THIS IS AS REAL AS IT GETS. NOWHERE IN THE FLORIDA KEYS WILL BE SAFE.”
  • Twenty-five people have been confirmed killed around the Caribbean, including 11 people on French St Martin and St Barts, four in the US Virgin Islands, three on Puerto Rico, two on Dutch St Maarten, one person in Anguilla and a two year old in Barbuda.
  • Category-four hurricane Jose threatened landfall in the eastern Caribbean, complicating relief efforts for islands that have only just emerged from Irma’s winds. On Barbuda, where the prime minister estimated 90% of buildings were destroyed, a mandatory evacuation moved people to the larger sister island of Antigua.
  • Another storm, Katia, was downgraded to a tropical depression as it pushed onto land from Mexico’s Gulf coast. Two people were killed in a mudslide in Veracruz, according to the AP.

The situation keeps changing in Florida as Irma looks like now going up over the keys and then up the west coast, depending on when an dhow much it veers north.

Irma will regain strength as it moves away from Cuba, with winds predicted of more than 110mph by the time it reaches the Florida Keys early Sunday.

The latest projections from the National Hurricane Center show the storm moving at about 9mph, with winds of 125mph, still over Cuba’s northern shore. The hurricane has not yet turned north back over warmer waters.

Irma’s current projected course shows the eye making landfall three times on Florida: first over the Lower Keys, where meteorologists expect devastating storm surges; then over Cape Coral or Fort Myers, in south-west Florida; and finally it is expected to come within range of Tampa Bay, the state’s third most populous city.

This will play out slowly of the next three days, it has been a slow motion wrecking storm.

The cost of US hurricanes

The cost of US hurricanes can be huge. NOAA (National Centers for Environmental Information) estimates the economic impact of Hurricane Harvey at about $180 billion. Some comparisons:

  • Harvey (2017) $180B
  • Katrina (2005) 160B
  • Sandy (2012) $70B
  • Andrew (1992) $48B
  • Ike (2008) $35B

Of course inflation, increased population and increased industrialisation need to be taken into account. And this is just the US costs, hurricanes ending up hitting the US coast have often already wreaked havoc in the Carribean.

And the cost of Harvey is yet to be determined accurately. Five days ago an estimate was $108 billion – see Harvey is likely to be the second-most costly natural disaster in U.S. history.

And there’s more bad news – Hurricane Irma is growing in strength and heading for Florida, passing by a number of Caribbean islands on the way.

Independent:  Hurricane Irma has become so strong it’s showing up as an earthquake on seismometers

Florida, Puerto Rico and the US Virgin Islands have declared a state of emergency

irma-5-sept.jpg

Washington Post: Catastrophic Hurricane Irma — now a Cat 5 — is on a collision course with Florida

Hurricane Irma is an “extremely dangerous” Category 5, barreling toward the northern Lesser Antilles and Southern Florida. It’s already the strongest hurricane ever recorded outside the Caribbean and the Gulf of Mexico, and it’s likely to make landfall somewhere in Florida over the weekend.

If it does, the impact could be catastrophic.

The storm is life-threatening for the United States, including Puerto Rico, the U.S. and British Virgin Islands, the Dominican Republic, Haiti, Cuba and the southeastern Bahamas. Hurricane warnings have been issued for the northern Leeward Islands, Virgin Islands, and Puerto Rico. A hurricane watch is in effect for Hispaniola and southeastern Bahamas.

With maximum winds of 185 mph, Irma is tied for the second strongest storm ever observed in the Atlantic. And in its Tuesday morning discussion, the National Hurricane Center said the storm is in an environment “ideal for some additional intensification.”

And inevitably these hurricanes raise a bigger storm, climate change debate.

As Irma looms, Harvey makes climate change clearly visible.

Hurricane Harvey is the biggest rain event in the nation’s history and could turn out to be one of the most destructive storms ever. Thousands of people are out of their homes, the death toll has been climbing, and people are still being rescued. The magnitude of Harvey shows the impact of climate change.

The Gulf of Mexico has increased in temperature because the planet is getting warmer, which made the storm catastrophic. Harvey is the symbol of what climate change impacts look like.

Harvey brewed in the Gulf of Mexico, but Irma is coming in off the Atlantic Ocean.

From WaPo six months ago: Gulf of Mexico waters are freakishly warm, which could mean explosive springtime storms

Water temperatures at the surface of the Gulf of Mexico and near South Florida are on fire. They spurred a historically warm winter from Houston to Miami and could fuel intense thunderstorms in the spring from the South to the Plains.

In the Gulf, the average sea surface temperature never fell below 73 degrees over the winter for the first time on record, reported Eric Berger of Ars Technica.

Galveston, Tex., has tied or broken an astonishing 33 record highs since Nov. 1, while neighboring Houston had its warmest winter on record.

The abnormally warm temperatures curled around the Gulf, helping Baton Rouge and New Orleans reach their warmest Februaries on record.

Meanwhile, a ribbon of toasty sea surface temperatures streamed north through the Straits of Florida supporting record-setting warmth over parts of the Florida peninsula.

The warm water temperatures in the Gulf of Mexico, in particular, could mean that thunderstorms that erupt over the southern and central United States are more severe this spring. Berger explained in his Ars Technica piece: “While the relationship is far from absolute, scientists have found that when the Gulf of Mexico tends to be warmer than normal, there is more energy for severe storms and tornadoes to form than when the Gulf is cooler.”

The implications of the warm water for hurricane season, June 1 to Nov. 30, are less clear.

The implications seem to be more clear now.