Participate in Real Science – Help Classify Tropical Cyclone Winds

Cyclone Center, now in its third year, is a website that allows citizen scientists like you to help meteorologists like us determine the maximum wind speed (or “intensity”) of historical global tropical cyclones.   We need your help to complete this ambitious project.

Why am I needed?

First,  there are way too many images (nearly 300,000!) for us to do it alone!  Second, your responses as a group are almost always just as good as an expert!  And third, there are disagreements in the historical record that must be addressed.    For instance, there are studies in published literature that suggest that typhoon activity is both increasing and decreasing in the western Pacific Ocean. Clearly both cannot be true!

Why are there questions about tropical cyclone data? 

Spawns of El Nino? Hurricanes Iselle and Julio Aim For Hawaii

Cyclone Center is tracking two storms as we classify this afternoon.

It has been quite a remarkable week in the eastern and central Pacific that has culminated in two hurricanes taking aim at the Hawaiian Islands today.  Hurricane Iselle has shown herself to be quite resilient as she has maintained her hurricane strength despite moving over cooler ocean waters.  Hurricane warnings are out for the big island as residents prepare for a significant event.  Meanwhile, Hurricane Julio is following close behind, continuing to intensify despite his movement over cooler waters.  The graphic below from the Central Pacific Hurricane Center shows the likelihood of significant winds over the next few days in the islands:

Kulab says “Please Classify Me!”

Not much has been happening in recent weeks in the tropics (with the notable exception of the extreme western Pacific), so allow me to try generate some fake excitement by highlighting one of our four featured storms – KULAB.  Why Kulab?  

A Quiet Hurricane Season in the Atlantic?

The official start of the hurricane season in the North Atlantic was June 1 and most experts are predicting a relatively quiet season, pointing to relatively cool water temperatures in place and a developing El Nino in the Pacific.   El Nino can be thought of as a substantial warming of ocean water in the central and/or eastern Pacific which in turn alters global weather patterns.  Atlantic hurricanes typically encounter more hostile atmospheric conditions during El Nino events, limiting their potential to develop and strengthen.  Most of the inactive seasons in the Atlantic over the past 20 years have occurred during El Nino events.

Do cyclones develop ‘off-season’ in the Atlantic?

Headquarters for the U.S. National Hurricane Center

In the Atlantic, the official dates for the hurricane season are 1 June – 30 November. This certainly doesn’t mean that cyclones only exist during this time frame, yet 97% of all cyclones that have developed have occurred during those months.  While we really won’t know exactly how many cyclones have developed out of season prior to 20th century technological advances, there is evidence of off-season storms in the Atlantic dating back to May of 1771, and more recently tropical storm Beryl in May of 2012. Most cyclones that develop out of season do not typically impact the U.S., but there have been more than handful that have, giving us pause to think what a fickle planet our Earth can be.

Featured Storm – Super Typhoon Fengshen (2002)

Origin and Track of Typhoon Fengshen

Typhoon Fengshen was the strongest storm of the 2002 Pacific typhoon season. It developed on July 13 near the Marshall Islands and rapidly intensified due to its small size. Fengshen went from being a tropical depression to a cyclone in only 6 hours. By July 15, Fengshen was given typhoon status, and after initially moving to the north, it turned toward the northwest. On July 18, the typhoon reached its peak intensity of 185 km/h (115 mph), according to the Japan Meteorological Agency; the Joint Typhoon Warning Center (JTWC) estimated peak winds of 270 km/h (165 mph). Disparities like this between agencies are the driving force behind the creation/purpose of  Cyclone Center, and with your help these dissimilarities can be smoothed out. Your classifications are important to us, so we ask that you please take a moment and provide your input on Typhoon Fengshen to help us determine its peak winds.

Typhoons Fengshen (north) and Fung-Wong (south) undergo the Fujiwhara effect

The JTWC estimated that Fengshen was a super typhoon for five days, which broke the record for longest duration at that intensity. This record would later be tied by Typhoon Ioke in 2006. While approaching peak intensity, Typhoon Fengshen underwent the Fujiwhara effect with Typhoon Fung-wong, causing the latter storm to loop to its south. The Fujiwhara effect is when two nearby cyclonic vortices orbit each other and close the distance between the circulations of their corresponding low-pressure areas. Interaction of smaller circulations can cause the development of a larger cyclone, or cause two cyclones to merge into one.

Fengshen gradually weakened while approaching Japan, and it crossed over the country’s Ōsumi Islands on July 25 as a severe tropical storm. The typhoon swept a freighter ashore, killing four of the 19 crew members aboard. In Japan, Fengshen dropped heavy rainfall that caused mudslides and left $4 million (¥475 million Japanese Yen) in crop damage. After affecting Japan, Fengshen weakened in the Yellow Sea to a tropical depression, before moving across China’s Shandong Peninsula and dissipating on July 28. The typhoon produced strong winds and heavy rain in Japan. A station in Miyazaki Prefecture reported the highest rainfall in Japan with a total of 717 mm (28.2 in). Most of the precipitation fell in a 24 hour period, and the heaviest 1 hour total was 52 mm (2.0 in) in Taira, Toyama. The remnants of Fengshen produced heavy rainfall in northeastern China. The storm affected the capital city of Beijing, becoming the first storm to produce significant impact there since Typhoon Rita in 1972.

– Kyle Gayan is an undergraduate student in Atmospheric Sciences at the University of North Carolina at Asheville and is also a retired USAF Master Sergeant; his 20 years of service was spent exclusively in the weather career field. He recently joined the Cyclone Center team as a classifier and contributor to our social media.

Featured Storm – Hurricane Rita (2005)

Hurricane Rita is now the featured storm from the 2005 record-breaking Atlantic season.  She was the third Category 5 hurricane of the season, producing an estimated $10 billion in damage across the southern United States.

Hurricane Rita at peak intensity in the Gulf of Mexico

Less than a month after Katrina had hit the central Gulf region, Rita was in the works.  On September 16^th, 2005 a tropical wave interacted with the remains of a trough from a dissipating stationary front. This was her beginning.  The next day, near the Turks and Caicos Islands, this interaction turned into a tropical depression.

The depression started moving westward and Tropical Storm Rita was named that afternoon.  Rita began a rapid intensification phase when she moved through the Florida Straits on September 20^th, with a wind speed of over 60 knots. That day she reached hurricane status and peaked at Category 2 intensity on the Saffir-Simpson scale. When Rita entered the Gulf she went from a Category 2 to Category 5 intensity in just 24 hours. This was only the third time in history that two Category 5 storms had been recorded forming in the Atlantic during the same year, and it was the first time that two hurricanes reached Category 5 intensity in the Gulf of Mexico in the same year.  Rita reached her peak intensity on September 24^th when her sustained winds exceeded 155 knots.

Track of Hurricane Rita (2005)

Rita began weakening as she made landfall just east of the Texas/Louisiana border on September 24^th.  She was still at tropical storm intensity when she reached northwestern Louisiana later that day,  turning northeastern and merging with a frontal system.  She produced torrential rainfall of as much as 5 to 9 inches in many areas of Louisiana, Mississippi, and eastern Texas. Storm surge flooding and wind damage were some of the major causes of the devastating damage Rita left behind, along with  an estimated 90 tornadoes across the southern US.

Rita was definitely a memorable one.  Luckily, with forecasters being on alert, they evacuated an estimated 3 million people from their homes in preparation for the storm.  Of course, with Katrina only being in the recent past, no one was prepared for the damage Rita would cause.  She was directly responsible for seven deaths, and indirectly responsible for 113.

Go to Cyclone Center today to start classifying Rita.  She was a historic, one-of-a-kind storm. To learn more about her, you can go to US National Hurricane Center tropical cyclone report for Rita.

– Kelly Dobeck is an undergraduate student in Atmospheric Sciences at the University of North Carolina at Asheville.  She recently joined the Cyclone Center team as a classifier and contributor to our social media.  

Hurricane Katrina and the Intensifying Coastal Threat

This week Cyclone Center introduces Hurricane Katrina (2005) as one of our featured storms.  This is the 8th anniversary of Katrina’s assault on the northern Gulf of Mexico coast.  The city of New Orleans, despite a massive system of protective levees and pumps, lost over 1500 souls, almost all from drowning when water flooded about 80% of the city.  Since then,  millions of dollars have been spent on the repair and upgrade of the levee system in and around metro New Orleans.  Are they ready for the next one?

“We’ll be absolutely ready for it,” said U.S. Army Corps communications officer Wade Habshey in a recent Discovery News article. “What we have in place now can withstand a Katrina-level storm.”

New Orleans flooding caused by 60 kt. winds, 10-14 ft. storm surge. Category-5 values: 140 kt winds, 25-35 ft. storm surge.

But what exactly is a “Katrina-level” storm?  Winds in downtown New Orleans rarely exceeded minimal hurricane force at the peak of the event.  Storm surge and the strongest winds from the weakening Katrina were focused well to the east in coastal Mississippi.  And yet levees failed, water flooded significant portions of the city, and over 1,500 perished.

An even bigger concern in the long-term are geological changes occurring in the area; coastal portions of Louisiana are sinking into the ocean as climate-forced sea levels continue to rise and land areas sink.  This exacerbates the threat of  hurricanes for a region that experiences one on average every couple of years.  Many climate scientists now believe that hurricanes will be stronger on average in the future as the ocean, which provides the fuel for the storms, continues to warm.

What more should be done?  Government officials exude confidence that the improvements to the levy system will hold up, but we’ve heard that story before.  Claims were made soon after Katrina that the levee system was designed to withstand a Category-3 storm , not something like “Katrina’s strength”.  We’ve already seen that Katrina wasn’t even a hurricane in New Orleans – what happens when a real Category-4 or 5 storm hits the area?  We can only hope that residents will have left, because it’s a very good bet that there will be little dry land to stand on.

– Chris Hennon is part of the Cyclone Center Science Team and Associate Professor of Atmospheric Sciences at the University of North Carolina at Asheville

New Developments on Tropical Cyclones and Climate Change

One of the goals of the Cyclone Center project is provide a more definitive answer on how tropical cyclones (TCs) have been responding to the dramatic changes that our climate is undergoing.  It is difficult for meteorologists to determine how strong tropical cyclones are getting because we rarely observe them directly, relying primarily on satellite data to give us a decent estimate of the wind speeds.  But as you can imagine, it is very hard to determine the maximum winds in a hurricane when you are in the hurricane itself, let alone flying more than 22,000 miles above it!  Our record of tropical cyclones is by no means nailed down.

Featured Storm – Cyclone Alibera (1989)

Citizen scientists working at Cyclone Center now have four storms to choose from when they sign in to classify.  Our first set of storms includes Cyclone Alibera, a long-lasting Southern Indian Ocean storm that thrashed coastal Madagascar on New Years Day 1990.

The path the Cyclone Alibera followed during the first 3 weeks of its life.  The storm formed in the upper right portion of the map and moved toward the lower left.

Alibera formed in the Indian Ocean on December 14, 1989 and did not dissipate until January 7, 1990 – a whopping 25 days!  During that time, the storm traveled several thousand kilometers, which included a big loop.  Cyclones like Alibera are steered by the large-scale winds in the atmosphere.  Sometimes when these winds are weak and/or changing, storms can move in strange ways.  The first image shows the long and interesting track of Alibera.

During the second week of Alibera’s life, the atmospheric and ocean conditions became very favorable for intensification.  The storm rapidly strengthened from a subdued tropical storm into a minor or very intense tropical cyclone, depending on who you believe.

Two forecast centers tracked Alibera during this time.  The Joint Typhoon Warning Center, or JTWC, is a U.S. Navy and Air Force office in Hawaii that monitors the western Pacific and Indian Oceans.  Based on imagery like those that citizen scientists are analyzing in Cyclone Center, analysts determined that Alibera was a “Very Intense Cyclone”, with wind speeds on the threshold of Category 5 intensity in the Saffir-Simpson scale.   However, analysts at a French forecast centre on La Reunion, an island off the east coast of Madagascar, determined that Alibera was only a minimal Category 1 tropical cyclone at the same time.  The figure below shows that these differences in opinion were not limited to the time of Alibera’s strongest intensity.

Alibera intensities as determined by JTWC and Reunion forecast centers.

This is why Alibera is one of the first storms that we would like citizen scientists to analyze.  We want to know what YOU think Alibera’s intensity was – we will use this information to reconcile these big differences.

Alibera eventually would make landfall in coastal Madagascar on New Year’s day, killing 46 people.  Though not widely known outside of the southern Indian Ocean region, Alibera is certainly a storm worthy of our attention – and a good example of how tropical cyclone forecasters can wildly disagree on a storm’s intensity when observations are not available.

Log on to Cyclone Center today and classify Alibera.

– Chris Hennon is part of the Cyclone Center Science Team and Associate Professor of Atmospheric Sciences at the University of North Carolina at Asheville