Thursday, March 20, 2008

What Follows Two Days Of Rain?

It is a very old joke but it still brings a smile to my face. What follows two days of rain? Why, Monday, of course.

I hate to admit but I’ve used that little gag from time to time on television following a wet, dreary weekend across South Florida. It is an admittedly weak attempt to make folks feel a little better after the weatherman spoiled their weekend of fun with lots of rain.

Our most recent period of weekend weather has been mostly good including the gorgeous sunshine, brisk breeze and cool temperatures of last Saturday and Sunday. And, according to a new study, more great weekends may be in our future.

Thomas Bell, an atmospheric scientist at NASA’s Goddard Space Flight Center, discovered that storms developing during the workweek tend to produce more rain than storms that occur on the weekend.

Using data from NASA’s Tropical Rainfall Measuring Mission satellite (TRMM), Bell examined rainfall patterns across the Southeast from 1998 to 2005. He found that more rain fell between Tuesdays and Thursdays than between Saturday’s and Mondays. And, those weekday storms tended to be more violent that storms on the weekend.

Bell’s study reports that afternoon rainfall peaked on Tuesday’s, when an average of 1.8 times more rain fell than on Saturdays. According to Bell’s study, Saturdays saw the least amount of afternoon rain.

Of course, the obvious question facing Bell and his colleagues was why was it raining more during the workweek? The answer? An increase in pollution.

Bell compared his weather data with information from the Environmental Protection Agency on particulate matter associated with pollution across the country from 1998 to 2005. The data suggests pollution tended to reach its peak during mid-week.

“If two things happen at the same time, it doesn’t mean one thing caused the other,” Bell told the editors of Weatherwise Magazine. “But it’s well known that particulate matter has the potential to affect how clouds behave, and this kind of evidence makes the argument for a stronger link between pollution and heavier rainfall.”

That particulate matter tends to increase during the workweek, Bell says, thanks to busy roads and highways, active businesses and factories, and the pace of life in the 21st century. Bell believes that extra pollution helps “seed” the cloud, enhancing their rainfall potential.

During weekends there is lot less traffic on the highways, many businesses and factories shutdown while more people have a couple of days off from work. The result: less rain on Saturday and Sunday.

“It’s eerie to think that we’re affecting the weather,” Bell said. “It appears we are making storms more violent.”

Based on Bell’s new study, it might be time to make a few amendments to that old joke about weekend rain. The new version? What follows five days of rain? The weekend.

Posted at 12:38 PM

Wednesday, March 12, 2008

The Super Storm

I thought March 8, 1993 was going to be another routine day of weather forecasting here in South Florida. March is one of my favorite months since it often features warm, dry days and cool, clears nights. The heat and oppressive humidity of summer usually are still a few weeks away.

When I arrived at the television station that Monday afternoon and began examining the weather maps I was shocked at what they showed. The long-range computer models were predicting a massive storm would sweep across the eastern United States beginning on Friday, March 12th.

This couldn't be right, I thought. After all, the models were predicting a storm of historic proportions, a storm comparable to a major hurricane. Still, the model data couldn't be ignored so I included a chance of thunderstorms in the long-range forecast.

When I returned to work the next day I was anxious to see what the computer models were saying about the alleged super storm. Back in 1993, computer modeling was in its infancy so it was quite common to see one model run predict a giant storm while the next run of the computers would suggest sunshine was in the forecast.

Yet, on Tuesday March 9, the computer model continued its insistence that a massive storm was coming our way. Wednesday and Thursday's model run remained remarkably consistent convincing me that a major storm was headed for the East Coast.

In 1993, TV stations didn't broadcast 24 hours a day so I had to convince our management that we needed to stay on the air, all night long, to cover this massive storm. I'm glad we did because I had a front row seat to one of the most remarkable events in weather history.

It's been called many names: the Storm of the Century, '93 Superstorm, the No-Name Hurricane, the White Hurricane or the Great Blizzard of '93. Whatever name you choose it will be remembered for its massive size (at its peak it stretched from Canada to Central America), it remarkable intensity (the storm's lowest pressure was 960 mb, comparable to a category 3 hurricane) and its impact (it produced $10 billion in damages).

The storm hit Florida's west coast first producing a squall line of thunderstorms that generated hurricane force wind. I remember talking with viewers who described near continuous lightning as the thunderstorms rolled across the eastern part of the state. Ten tornadoes were reported in
Florida including one that claimed three lives.

After moving across the Sunshine State, the squall line kept on going southeast slamming into Cuba with 100 mph winds. Power was knocked out across the entire island. It was the most powerful storm, other than a hurricane, to ever strike Cuba.

Further north the storm produced a winter nightmare across the eastern seaboard burying cities with several feet of snow and whipping winds of more than 60 mph. One town in Tennessee recorded 60 inches, while more than three feet of snow fell across Pennsylvania and upstate New York.

Birmingham, Alabama picked up an amazing 17 inches of snow with gusty winds producing 6-foot drifts. I remember talking with a reporter from a Birmingham TV station who said, not surprisingly, that the entire city was shut down.

So were most airports from Atlanta to Nova Scotia. It is estimated that the massive storm impacted 130 million Americans, about half the population in 1993.

When I left the TV station around 6 AM on Saturday, March 13, the heavy rains had ended but the gusty winds were still blowing. As I drove home with the sun beginning to rise, I could see some wind damage across our area. Thankfully, it wasn't too significant.

In fact, Palm Beach fared pretty well with the Storm of the Century. For other parts of the United States, it would take several days to full recover from one of the most powerful storms in history.

I often remind young meteorologists that the computer models "are guidance, not Gospel." Yet, 15 years ago this week, the computer models were remarkably accurate in predicting the Storm of the Century.

Posted at 12:12 PM

Monday, January 21, 2008

Weather And Video Games

I'm supposed to be a grownup. After all, I'm over 50 years old, my hair is turning gray and I'm lucky enough to have a wonderful family. Yet, I'm still a kid at heart, which may explain my fascination with video games.

A few years ago a group of us at the TV station purchased the XBOX 360 video console and several games. Within a few hours, I was hooked, spending many more hours sitting in front on my television while madly pushing the "A", "X", "B" and "Y" buttons on the wireless controller.

One of the really neat aspects of the XBOX console is the ability to compete against video game enthusiasts around the world. With your XBOX 360 connected to the Internet, you can play games and have conversations with folks anywhere on the planet. It was a real hoot the first time I played the Tiger Woods golf simulation game with someone from Australia.

So, why am I writing about video games when I should be talking about the weather? Well, it's because video game programmers are including more real-world information (like the weather) in their games. And big companies, like The Weather Channel, are jumping on the video game bandwagon.

Take, for example, NCAA Football 08, a popular college football simulation game. Published by Entertainment Arts Sports (the same folks who make the top selling Madden NFL series). NCAA Football 08 captures the excitement and passion of college football. One of the game's newest features is a tie-in with the Weather Channel.

After choosing teams for the game, gamers can click on The Weather Channel Live Feed to receive the current weather at the stadium. Let's say, for example, that you picked the University of Miami Hurricanes to play the Florida State Seminoles in Tallahassee. After clicking on The Weather Channel Feed, your game will be played under the current weather in the state capitol, whether is sunny, wet, chilly or hot.

One of the most popular video games in history (it has sold more than 18 million games worldwide) is The Sims. Published by Electronic Arts, The Sims lets you create your own little world, an alternate reality of homes, businesses, neighborhoods and cities.

The most recent Sims game, SimCity Societies, even incorporates the effect of global warming. In the game, players build a community by placing roads, buildings and power sources throughout the region. The power sources range from options that emit high levels of carbon dioxide to more environmentally friendly alternatives like solar power and wind farms.

The game actually monitors the carbon released into the atmosphere as well as natural disasters like droughts, heat waves and powerful storms.

The video gamer is presented with a series of real-world issues that make the game seem more life-like than anyone could imagine.

"We have the opportunity to demonstrate the causes and effects of global warming," said Steve Seabolt of Electronic Arts. "We can educate players how seemingly small choices can have a big global impact."

Weather plays a big role in other video games, too. In Tiger Woods PGA Tour 08 you need to calculate how gusty winds will affect your shot to the green. And, in MLB 2K7, a simulation of major league baseball published by 2K Sports, rain delays are part of the video game just as in real life.

The goal is make the game more realistic. The addition of real-world information-like The Weather Channel Live Feed or the impact of global warming-it would appear that video game programmers are succeeding.

I'd like to write more about weather and video games but that guy in Australia wants to play golf again. Like I said, I'm supposed to be a grownup.

Posted at 1:19 PM

Friday, January 11, 2008

2007 Storm Season In Review

The race was on. Was it going to become the last storm of the 2007 hurricane season (the name would be Pablo) or the first storm of the 2008 season (the name would be Arthur)?

That was the dilemma facing forecasters at the National Hurricane Center as the new year approached. An area of disturbed weather in the far eastern Atlantic Ocean was gaining tropical characteristics and might develop into tropical cyclone. But, when?

If the system was named before the clock struck midnight on December 31 st it would be called Pablo and be part of the 2007 season, and if it formed on the first day of the new year it would be named Arthur and be the first storm of the 2008 season.

"The system has been producing gale-force winds, mainly to the north and east of its circulation center," senior hurricane specialist Richard Knabb told the Miami Herald. "It could become a sub-tropical system."

As it turned out, the system fizzled and eventually fell apart meaning the 2007 hurricane season has officially come to a close. The final tally:

14 named storms, six hurricanes and two major hurricanes.

Still, not everyone agrees with those numbers.

"They seem to be naming a lot more than they used to," Neil Frank, a former director of the National Hurricane Center told the Houston Chronicle. "This year, I would put four storms in the very questionable category, and maybe even six."

Frank, now the chief meteorologist for a Houston TV station, says Chantal, Eric, Gabrielle, Ingrid, Jerry and Melissa may not deserve tropical storm status because each system had a relatively high central pressure. Each system did have sustained winds of 39 mph, the criteria to be classified as a tropical storm, but only for a brief period of time.

Frank told the newspaper that he prefers using the central pressure to measure the intensity of a tropical system, because it can be directly measured by aircraft dropping an instrument into a tropical cyclone. "In the past, we would have waited to see if another observation supported naming the system," Frank said. "We would have been a little more conservative."

Officials had the National Hurricane Center believe that wind speeds are the true indicator of a storm's status. "For at least the last two decades, I am certain most, if not all, the storms named this year would have also been named," said Bill Read, deputy director of the hurricane center told the Chronicle.

Thanks to new technology, like the QuickSCAT satellite, more accurate wind measurements are available. Read argues that it only makes sense to use the best technology to quickly determine if a system has reached tropical storm strength.

"An oncologist today would use the latest technology for determining and assessing one's cancer," Read said. "Would you use a doctor who only used X-rays instead of the latest MRI?"

Determining an accurate account of tropical storm activity is important in a number of areas. The insurance industry uses the numbers to help set homeowner rates, researchers need the data to determine trends in hurricane activity and scientists use the information to determine whether global warming is influencing hurricane activity.

Before the age of weather satellites, no one really knew how many tropical storms and hurricanes formed each year, especially in the far reaches of the ocean. Today, however, every suspicious swirl is closely examined, just like that disturbance in the eastern Atlantic last weekend.

Was it going to be the last storm of 2007, the first storm of 2008 or another candidate for controversy? Maybe it was a good thing it didn't develop after all.

Posted at 12:42 PM

Friday, December 07, 2007

Tornado Tragedy

March 1, 2007 was an unusually warm day in Enterprise, Alabama, a small community in the southeastern part of the state. With temperatures expected to top 70 degrees and humidity over 60 percent, it was a sign that spring was just around the corner. For students at the local high school, the warm weather and a scheduled early dismissal couldn't come at a better time.

Unfortunately, that balmy, humid atmosphere was a harbinger of change, the proverbial calm before the storm as a powerful cold front swept across the region. The front, which would stretch from Minnesota to the Gulf Coast, was being pushed eastward by a ferocious Jet Stream.

Those gusty upper level winds would spawn more than 31 tornadoes across several states including a huge twister that struck Enterprise High School, killing eight students and injuring dozens more. The twister collapsed concrete walls, overturned cars in the school's parking lot and ripped apart the football stadium.

The tornado was 500 yards wide, on the ground for 10 miles and produced winds of 170 mph. It was the first killer tornado at a school since 1990 and the deadliest single twister in the United States in 40 years.

At first, school administrators came under some criticism for not dismissing the students early. Residents near the high school said they had heard warning sirens long before the tornado slammed into the high school, and school officials admit being told of the tornado threat three hours in advance.

But administrators at Enterprise High School said the weather was too violent to let the students leave the building, and they were worried that canceling classes would lead to even more carnage if the students were outside the high school when the tornado struck.

“I don't know of anything they didn't do," Alabama Governor Bob Riley told reporters after touring the damage. "If I had been there, I hope I would have done as well as they did."

Now, a six month long assessment by the National Weather Service agrees, concluding that high school officials and students followed appropriate safety measures during the tornado outbreak.

“Dismissing the students could have been just as dangerous,” said Glenn Lussky, the assessment team leader “Tornado warnings were in place the entire time, and the team agreed that shelter in place was the best response.” The report says the eight fatalities at the school were due to structural failure of the roof and walls, not the decision of the administrators.

Still, Lusky’s team says that shelter, in this case Enterprise High School, needs to have hardened safe rooms to survive future tornadoes. A hardened safe room, lined and topped with concrete, and without windows is designed to survive severe sustained winds and high wind gusts.

While a tornado the size and intensity that hit Enterprise, Alabama is virtually impossible in South Florida, comparable winds have occurred with hurricanes. In 1992, Hurricane Andrew produced sustained winds of 165 mph as it tore through southern Miami-Dade County.

More than $25 billion in damages and hundreds of destroyed homes led to new, tougher building codes. In recent years, all new schools built in the area have hardened safe rooms to act as shelters during periods of evacuations. Lusky’s team would like to see that trend grow around the country, especially in areas susceptible to large, powerful tornadoes.

“The tragic events of March 1 show that even when people have ample time and opportunity to take cover from a devastating tornado, the need for proper shelter is imperative,” said Conrad C. Lautenbacher, the head of the National Weather Service. “Despite warning lead times that exceeded national standards, many lives were lost. Our team concluded that survival in violent tornadoes often depends on reaching an adequate hardened safe room.”

Thanks to Frances, Jeanne and Wilma the term “safe room” is well known here in South Florida. Lusky and the folks at the National Weather Service would like that phrase to be commonplace around the country, too.

Posted at 12:36 PM

Friday, November 30, 2007

2007 Hurricane Season Ends Quietly

The 2007 hurricane season ended quietly on Friday without a tropical storm, disturbance or hurricane in sight. For all intents and purposes, the season really came to a close in late October when Hurricane Noel swept through the Caribbean and briefly threatened Florida.

The National Hurricane Center reports 14 storms formed this year, above the long-term average of 10 tropical storms. Still, most of the 14 were weak, short-live systems that were only a concern for shipping.

Only six hurricanes developed in 2007 with three, Dean, Felix and Humberto, making landfall. Dean and Felix reached rare category five status before slamming into Central America and Mexico. Humberto was a weak category one hurricane when it struck the southeast coast of Texas.

For the second consecutive year Florida was not hit by a tropical storm or hurricane. While Noel did get our hearts beating a little faster back in October, the storm’s biggest impact was significant beach erosion along the coastline.

Overall, folks in hurricane country along the United States coastline are more than happy with the 2007 hurricane season.

For the hurricane research community, however, 2007 will be remembered for the loss of two legends in tropical meteorology. Late last week, Herb Saffir, the man who helped create the Saffir-Simpson Hurricane Scale, died in his Miami home.

In early August, Dr. Robert Burpee, a past director of the National Hurricane Center and one of the top researchers in tropical meteorology, passed away in Miami following a long illness.

Of the two, Saffir is probably the better known thanks to the creation of his hurricane scale back in the late 1960’s. Working with Robert Simpson, the director of the hurricane center at the time, Saffir came up with a system to rank the destructive capability of a hurricane based on its wind speed and storm surge.

“Dividing hurricanes into categories was an idea whose time had come,” former hurricane specialist Mile Lawrence told the Miami Herald. “It was a wonderful way to collapse the information into a way that was easier to understand.''

Saffir also worked to strenghten building codes in South Florida and was instruemnetal in the implementation of a new state-wide building code considered the strongest in the nation.

“Driving around south Florida I can see the engineering work I have done,” Saffir told the Georgia Tech Alumni Magazine. “It’s there in the shape of buildings and bridges. It is there in the fact that the building code we use. I think I’ve left a little mark.”

There is no doubt among hurricane researchers that Dr. Robert Burpee also left “a little mark.” While he was director of the National Hurricane Center for two years from 1995 to 1997, it is in the research field that Burpee will be best remembered.

“Bob was one of those unsung heroes, a pioneer and scientist that helped shape the data we use today,” said Florida Division of Emergency Management Director Craig Fugate.

A veteran of more than 250 flights into hurricanes, Burpee was among the first who proposed using a jet to obtain environmental data around a hurricane. By sampling the atmosphere near the storm, forecasters had a much clearer sense of where the hurricane might be headed next. Max Mayfield, the former director of the hurricane center, says Burpee’s work added an additional “10 to 15 percent improvement in track forecasts.”

In 1995, Burpee helped formed the NOAA/FEMA Hurricane Liaison Team, which integrated emergency managers and hurricane forecasters to provide residents with important information. Burpee was part of countless research projects and the author of dozens of papers.

Both men’s contributions to hurricane research and safety will long be remembered as countless other top scientists build on the work of Herb Saffir and Bob Burpee.

Posted at 7:43 AM

Friday, November 16, 2007

Flying Into Hurricanes

It began as a dare, a bet among British and American pilots on July 27, 1943 as a hurricane was approaching the Texas Coast. It ended in history, as Colonel Joseph P. Duckworth became the first man to fly into a hurricane and return.

Duckworth actually flew into the hurricane twice that day, first with navigator Ralph O'Hair and a second time with weather officer William Jones-Burdick. In both cases, Duckworth's plane encountered severe turbulence and heavy rain before breaking into the storm's eye.

Within a few years, flights into hurricanes would become routine, an important source of information for hurricane forecasters. Today, the Hurricane Hunters, based at Keesler Air Force Base in Biloxi, Mississippi fly dozens of missions each season.

Remarkably, flying an airplane into a hurricane is not as crazy as it sounds. Still, some missions are more challenging than others. Writing in the October issue of the Bulletin of the American Meteorological Society, Neal Dorst recounts several rough rides.

On September 9, 1971 Hurricane Edith was approaching the Mosquito Coast of Nicaragua. Hurricane Hunters encountered "turbulence so severe that the pilots temporarily lost control of the aircraft," writes Dorst. "By the time they regained control, they had lost 1,000 feet of altitude."

During a flight into Hurricane Allen in August of 1980 the turbulence was so bad that "the shaking knocked loose the life raft and convinced one scientist that hurricane research was not his future," writes Dorst.

Perhaps the most memorable experience in the history of the Hurricane Hunters came in September of 1989 with a flight into Hurricane Hugo. Severe turbulence in the eye wall disabled one of the plane's four engines. "The plane had to orbit in the eye, burning fuel, while climbing to a safe altitude," writes Dorst. The aircraft limped back to Barbados where it remained out of commission for the rest of the season.

Despite these stomach-turning examples, the Hurricane Hunters have an excellent safety record. Since the first reconnaissance missions began in the 1940's, four airplanes have been lost in storms, the last in 1974 when an Air Force WC-130 went down in the South China Sea.

When Hurricane Noel was headed towards the Canadian Maritimes a few weeks ago, another type of hurricane reconnaissance was unveiled. The National Weather Service and NASA made history as the first unmanned aircraft flew through the storm.

The five-foot-long Unmanned Aircraft System (UAS) drone was launched from Wallops Island, Va., on a 20-hour-long mission through the hurricane. The pilotless aircraft is designed to fly into the eyewall of a hurricane at altitudes as low as 500 feet.

Scientists hope using unmanned aircraft will help fill a gap in near-surface data. The data have been hard to gather because of the safety risks of low-level flight.

"Unmanned flights at very low altitude are important since they give us unique insights and continuous observations in a region of the storm where the ocean's energy is directly transferred to the atmosphere just above. Attempting this type of research flight with our hurricane hunter aircraft would risk the lives of our crew and scientists," said Joe Cione, hurricane
researcher in Miami.

NOAA scientists are coordinating the unmanned flight to coincide with a manned Hurricane Hunter mission as well, providing a volume of data on Hurricane Noel from top to bottom. This level of information saturation is valuable to researchers, providing a more complete picture of storm structure and strength that becomes a valuable tool for meteorologists.

The hope, of course, is for better forecasts and increased warning time for coastal residents of an approaching hurricane.

Joe Duckworth became a legend when he accepted the challenge of British
pilots and flew into a hurricane. The first UAS flight a few weeks ago made
history, too, increasing our knowledge of tropical cyclones, the
greatest storm on Earth.

Posted at 11:59 AM

Monday, October 08, 2007

The Importance Of Weather Radios

The tornado that tore through the Eastbrook mobile home park near Evansville, Indiana on November 6, 2005 was 1,500 feet wide, moving at 70 mph and producing winds close to 200 mph. Worst of all, the twister struck in the middle of the night while everyone in the park was sound asleep.

The rare November tornado claimed 25 lives in southwestern Indiana including 20 people from the mobile home park. Residents said they couldn’t hear the tornado sirens and had no warning that a powerful storm was headed their way.

Earlier this year, the state of Indiana changed the weather warning process when Governor Mitch Daniels signed legislation requiring all mobile homes sold in Indiana must come equipped with a NOAA weather radio.

Dubbed “C.J’s. law”, for two-year-old C. J. Martin who died in the mobile home park, the new law went into effect on June 30. C.J.’s mom, Kathryn, had urged lawmakers to adopt the bill arguing that a weather radio can give residents advance warning of tornadoes.

Costing from $35 to $70, weather radios broadcast continuous weather information from the National Weather Service. When a weather warning is issued, including a tornado warning, the radio will sound an alarm, much like a smoke detector, alerting residents severe weather is in their area.

Still, the weather radio system is not ideal. Many weather radio owners turn off the device after getting fed up with false alarms and the weekly alert tests issued by the National Weather Service.

The Weather Service hopes a new weather warning system will fine-tune those weather advisories, reducing false alarms and making weather warnings more precise. Implemented last week, the new “storm-based” warning system switches from the traditional county-based warning to a more specific community-by-community alert.

“A storm-based warning focuses on a storm itself and the geographic area that might be affected by it,” said Eli jacks, a meteorologist with the National Weather Service. “We can really reduce the number of people being warned by reducing that geographic area.”

Using radar and computer modeling programs, the National Weather Service hopes to predict the moment a storm will hit a community, neighborhood or crossroad. The new alerts could reduce a warning area from thousands of square miles to a few hundred of square miles.

“It’s like shrinking the service area in a tennis court,” said John Ferree, a meteorologist with the National Weather Service in Norman, Oklahoma and one of the developers of the plan. “Even Roger Federer is going to hit the ball outside the lines if they’re close together.”

A version of the storm-based system has already been in use here in South Florida. When a severe thunderstorm is nearing Belle Glade in far western Palm Beach County, for example, only the communities directly in the path of the storm are put under storm warnings.

The system has worked well here and in trials in Indiana. “I think it has been a good system,” said Dave Tucek, who coordinates severe weather warnings in Indianapolis. “The idea being that there is no reason to warn the northern end of a county about something in the southern end of the county.”

The National Weather Service estimates the new storm-based warning system will save $100 million annually, mainly on cutting back on unneeded business closings or the amount of time people spent huddled in closets or basements during weather warnings.

More importantly, officials hope the new storm-based system will get weather advisories to people who will be directly impacted, giving folks the information and the time to prepare for severe weather.

Maybe with the new, more targeted warning system, folks will be more likely to keep their weather radios turned on, giving them a real chance to survive a tornado like the one that hit the Eastbrook mobile home park.

Posted at 11:47 AM

Monday, September 24, 2007

How Did Humberto Get So Strong?

It wasn’t supposed to be a big deal. When Tropical Storm Humberto took aim at the upper Texas coast last week forecasters were predicting periods of rain and blustery winds. Flooding was the primary concern with rainfall totals approaching ten inches expected in some areas. For folks who had gone through Hurricane Rita in 2005, Humberto was expected to be a walk in the park.

Yet, while residents of High Island and other Texas coastal communities slept, Humberto was changing, intensifying from a run-of-the-mill tropical depression into a category one hurricane. At 2 AM on September 13, Humberto made landfall with winds of 85 mph.

Humberto’s rapid intensification-from tropical depression to hurricane in 16 hours-surprised everyone, from the residents of Texas to the forecasters at the National Hurricane Center.

"To put this development in perspective, no tropical cyclone in the historical record has ever reached this intensity at a faster rate near landfall,” said National Hurricane Center senior hurricane specialist James Franklin. “It would be nice to know, someday, why this happened."

Someday, Franklin and other scientists may figure out why Humberto strengthened so quickly. Someday, researchers will know why Felix grew from a tropical storm to a category five hurricane in 51 hours earlier this year, or why Wilma exploded from a tropical storm to a category 5 hurricane in 24 hours.

Someday they will find the answer to rapid intensification of tropical cyclones but, for now, the process remains a mystery. And, a big concern for government officials anywhere a hurricane may make landfall. Craig Fugate, director of the Florida Division of Emergency management, says that his team always prepares for a storm that is one notch up from what is predicted.

While very warm water and low wind shear probably helped with the storm’s rapid intensification, the exact reasons why Humberto went from a depression to a hurricane in such a short period of time remains a mystery. Solving that mystery is the number one priority of the hurricane research community.

“While I was the Director of the National Hurricane Center, I can say that every talk that I gave at local, state and national hurricane conferences mentioned the concern over rapid intensification,” said Max Mayfield, former director of the Hurricane Center.

Back in June, forecasters at the National Hurricane Center began using a new computer model that eventually may help with the rapid intensification issue. Called “one of the most dynamic tools” for hurricane forecasters, the Hurricane Weather and Research Forecast Model (nicknamed HWRF) utilizes advanced physics of the atmosphere, ocean and waves to predict the future track and intensity of tropical cyclones.

“Over the next several years, this model promises to improve forecasts for tropical cyclone intensity, wave and storm surge, and hurricane-related inland flooding,” said Mary Glackin of the National Weather Service. “It will be one of the most dynamic tools available for our forecasters.”

Still, neither the HWRF nor any of the other hurricane models, predicted the rapid intensification of Humberto. In fact, it is fair to say that no one saw it coming.

Back in the first half of the 20th century-before orbiting satellites, long-range radars and the much talked about computer models-hurricanes really did sneak up on people. Other than a few random ship reports residents of coastal areas had no idea a hurricane was headed their way until the wind and rain swept across the coastline.

Today, we all know when a storm is about to strike, but until the rapid intensification mystery is solved, sometimes hurricanes will be full of surprises.

Posted at 11:42 AM

Wednesday, September 12, 2007

La Niña On Her Way?

The odds of a busy 2007 hurricane season just went up because the water temperature in the Pacific Ocean just went down. That drop in sea surface temperature marks the likely return of La Niña, and an expected increase in stress levels for residents in Florida and other parts of the United States coastline threatened by hurricanes.

Scientists at the Climate Prediction Center announced that La Niña is on its way. “While we can’t officially call it a La Niña yet, we expect that this pattern will continue to develop during the next three months, meeting the NOAA definition for a La Niña event later this year,” said Mike Halpert, acting deputy director of the Climate Prediction Center in Camp Springs, Md.

La Niña conditions occur when ocean surface temperatures in the central and east-central equatorial Pacific become cooler than average. These changes affect tropical rainfall patterns and atmospheric winds over the Pacific Ocean, which influence the patterns of rainfall and temperatures in many areas worldwide.

“La Niña events sometimes follow on the heels of El Niño conditions,” said Vernon Kousky, research meteorologist at the Climate Prediction Center. “It is a naturally occurring phenomenon that can last up to three years. La Niña episodes tend to develop during March-June, reach peak intensity during December-February, and then weaken during the following March-May”.

While past La Nina’s have been responsible for serious droughts in the western United States, it is La Nina’s influence on hurricanes in the Atlantic Ocean and, in particular, the current hurricane season that has caught the attention of local officials.

“Although other scientific factors affect the frequency of hurricanes, there tends to be a greater-than-normal number of Atlantic hurricanes and fewer-than-normal number of eastern Pacific hurricanes during La Niña events,” said retired NOAA administrator Conrad Lautenbacher.

A 1999 study on La Nina’ influence on Atlantic hurricane activity found that “the odds are significantly higher that the U.S. will experience greater (hurricane) impacts because of a larger number of tropical cyclones and higher intensities for each storm.”

The last La Nina lasted from 1998 to 2000, a period that saw 37 tropical storms and 26 hurricanes in the tropical Atlantic. Among the memorable storms during those years were Hurricane Georges that hit the Florida Keys, Hurricane Floyd that threatened Florida and Hurricane Irene that swept across South Florida.

Dr. William Gray’s team at Colorado State University recently updated their hurricane forecast for the remainder of the season. Gray thinks the next few months will be active forecasting 10 named storms, 6 hurricanes and three major hurricanes.

This latest news regarding the developing la Nina will not sit well with residents in Florida, the northern Gulf Coast states and other locales still recovering from the active hurricane seasons of 2004 and 2005. And, while everyone received a nice break from Mother Nature last year, it appears more and more likely that the 2007 hurricane season will be busy.

All because the water temperature is going down.

Posted at 11:36 AM