Topic: Hurricanes and Typhoons

[Astronuc]

The topic is much in the news since we are in the height of hurricane season in the SE US.

Two images taken from NOAA satellites on Saturday, SEP 4, 2004.  The latter is take at 0815, the other one earlier.

[Astronuc]

The Climate Prediction Center monitors Sea Surface Temperatures in the Pacific and Atlantic Oceans.�  An example in the Western Atlantic is - http://www.cpc.ncep.noaa.gov/products/hurricane/12wksst.html

The SST just east of Florida is about 3°C warmer than in June.�  The above site shows that the SST is between 29 and 30°C now.�  This is one reason for stronger hurricanes during late Aug through September.

Climate Prediction Center
http://www.cpc.ncep.noaa.gov/

http://www.cpc.ncep.noaa.gov/products/outlooks/hurricane.html - Hurricane outlook

[Astronuc]

Tracking weather including hurricanes over Florida and eastern Gulf of Mexico -

GOES Storm Floater 1
http://www.ssd.noaa.gov/PS/TROP/DATA/RT/float-ir4-loop.html (closeup SE US)

GOES Storm Floater 2
http://www.ssd.noaa.gov/PS/TROP/DATA/RT/float2-ir4-loop.html (wide view)

also

GOES-East-visible
http://www.ssd.noaa.gov/PS/TROP/DATA/RT/gmex-vis-loop.html

GOES-East-infrared
http://www.ssd.noaa.gov/PS/TROP/DATA/RT/gmex-ir4-loop.html

[Astronuc]

http://www.nytimes.com/2004/09/14/science/14hurr.html

Hurricane Ivan, churning over Cuba and the tip of Florida on Monday, continued to challenge forecasters, who said it could hit land in the United States as far west as New Orleans or as far east as Tallahassee, Fla.

[Astronuc]

GOES Floater Vis - Sep 15 - 1145 UTC

Image shows extent of hurricane Ivan as of early this morning.
Areas from Baton Rouge to Tallahassee should expect a lot of rain with heavy flooding in parts, particularly near coast.

[cassiopeiae]

here's an updated satellite image
(please spare New Orleans  :\'( )

-----------------------------------------------
http://www.noaanews.noaa.gov/stories2004/images/ivan091404-2015z.jpg

[Astronuc]

Hurricane IR Loop - Eastern Atlantic, Caribbean Sea and Gulf of Mexico
(Lat 8-38 N, Long 25-100 W)

http://www.goes.noaa.gov/HURRLOOPS/huirloop.html

[Astronuc]

Power of Hurrican Ivan - waves from the ocean surge driven by the winds into the Escambia Bay near Pensacola, Florida caused the collapse or loss of several decks of both spans on Interstate-10.  It was not tornados, but the power of the ocean.

The second photo shows the full extent of the damage to theInterstate 10 bridge that spans Escambia Bay, is seen with sections washed away in the aftermath of Hurricane Ivan, Friday, Sept 17, 2004, near Milton, Fla. (AP Photo/Kevin Glackmeyer)

This will have a significant economic impact on the area.

[Astronuc]

An additional perspective looking eastward toward bridge.

This is why one should pay attention to the weather when traveling, and why one does not drive across a bridge crossing a bay in the middle of a hurricane.

Sept 18 - The driver is so far missing.  Hopefully he or she will show up somewhere -  a family must be waiting.

Sept 25 - Update:  The driver was found dead - drowned in the cab of the truck.

(Photos are published by Reuters)

[Astronuc]

Forecasters Warn of More Bad Hurricane Years
By JOSEPH B. VERRENGIA, AP

(Sept. 17/Revised Sept. 26) - Ivan, Frances and Charley delivered three staggering blows to the Gulf Coast and Florida, as well as Caribbean island nations, all in just five weeks.  Then came Jeanne, which lashed cnetral to northern Florida, Saturday night through Sunday and Georgia by Monday.  Homeowners had re-install the same plywood over their windows figuring it couldn't get much worse.

Brace yourselves: Scientists say 65 million Americans living on the Gulf and Atlantic coasts should expect weather like this for another 30 years.  Maybe more.

Sure, it's hurricane season and storms happen.  But counting Alex, which swamped the Carolinas in August, that's five in six weeks. And that doesn't include tropical storms Bonnie, Gaston, Earl and Hermine.

"I don't remember this happening before in such a short period of time," National Hurricane Center director Max Mayfield told reporters, "and the season is only half-over."

It might be a generation before hurricane weather slips back into a quiet phase, he and other experts say.

"The hurricane threat is much greater than it was in the 1970s through early 1990s," said federal meteorologist Stan Goldenberg, who flew around Hurricane Ivan in research aircraft as it approached Mobile, Ala. "It could last another 10 to 40 years."

Goldenberg and other experts believe the current hurricane surge is part of an obvious storm cycle that probably has been waxing and waning for hundreds of years.

Roughly from 1970-94, Atlantic hurricane activity in the United States was relatively mild. Sure, there were monster hurricanes like Andrew in 1992 - its 177 mph winds killed 55 people in the U.S. and Caribbean and caused $26.5 billion in damage. Every year a big storm whips up - it's just that most fizzle before veering into a city.

Overall, the 25-year "quiet" period generated about half as many destructive storms as the previous stormy phase dating back to the 1920s, and about half as many as today's stormy phase appears likely to produce.

Since 1995, environmental conditions have shifted and the Atlantic has been spawning more strong storms. The number of major hurricanes has more than doubled. In the Caribbean, it's up by a factor of five.

Even with milder storm years in 1997 and 2002, the period since 1995 is the most active nine consecutive years on record, according to pioneering hurricane forecaster William Gray at Colorado State University.

Since 2000, the United States has been hit by an average of four powerful storms per season.

Forecasters have been warning of this for years. Even back in 1998 - a year that saw four hurricanes in September - Gray said: "We are going to see the return of some of these type of storms. People have to face up to it. The insurance industry has a major problem."

Last month, Gray tweaked his gloomy 2004 forecast downward, predicting 13 named storms rather than 14. He expected seven storms to blow up into hurricanes, three with sustained winds of 111 mph or greater.

So far, he's right.  If storms continue brewing, Gray might wish he had tweaked his forecast up, not down. And don't forget that last year, two more tropical storms developed in the Caribbean after the hurricane season formally ended Nov. 30.

Why is the storm cycle intensifying now? Scientists aren't certain what causes the decades-long shifts in the ocean-atmosphere interplay.

Hurricanes reflect the complex dance between the atmosphere and the oceans.

When the Pacific Ocean cools during the La Niña climate phenomenon, the Atlantic warms up, and more hurricanes are the result.  Over the Atlantic, wind shear that knocks down rising storms tend to slacken, while humid westerly winds from Africa's bulge grow stronger.

Scientists look for large pools in subtropical ocean where water is at least 81°F. The warm sea heats the air in a rising column, creating a center of moist low pressure.

Trade winds rush in toward this depression. Combined with the planet's rotation, they spin clouds counterclockwise (in the norther hemisphere) around this steamy core, or "eye" of the storm.

Most scientists agree that global warming plays little or no role in the number of storms in the current hurricane cycle.

Global climate models show that air pollution from industry and traffic will drive up average world temperatures by a degree or two this century. All that extra heat could fuel more stormy weather. And local evidence of temperatures rising may already be apparent with some glaciers melting and spring flowers blooming early. But so far, climate change is too uncertain and today's hurricane patterns are too complex to draw a connection.

"I don't think the warming now is anywhere near enough to account for the increase in hurricanes that we're seeing," said Robert Gall of the National Center for Atmospheric Research in Boulder, Colo. "To me, this is just a natural variation in the frequency of hurricanes."

Hurricanes are among nature's most powerful natural events. Spinning as fast as a race car, the wall of clouds can rise 10 miles into the stratosphere and span 400 miles, as wide as Kansas.

The amount of mechanical energy generated by a such a swirling storm translates to a power supply of 360 billion kilowatt hours per day - equal, by some estimates, to all of the electricity consumed in United States in six months.

Only 12 percent of the world's swirling storms spawn in the Atlantic. About 100 of these cyclones are reported annually worldwide.  Most of them crank unnoticed in the North Pacific and the Indian Ocean.

A large storm might seethe and spin for 3,000 miles, inhaling the energy from billions of tons of warm seawater. Incoming dry air from high pressure zones can choke it off, or landfall can quickly deflate it.

Forecasters are much less comfortable predicting how a storm will behave once it hits land. That's a major focus of their research now.

Ivan boasted 160 mph winds in the Gulf, but it quickly lost about half of its fury when it reached Alabama.  That's not always the case.  Hurricane Charley whipped up to a category 4 storm when it hit Florida's west coast. Andrew was just a tropical storm in the hours before it hit Miami.

Goldenberg said it's harder to forecast storm intensity than to accurately predict its path.  Since coastal residents now heed hurricane warnings, researchers are turning their attention to an underappreciated danger - downpours reaching inland for hundreds of miles.

[gcks]

May I ask something?
Although we don't have hurricanes in Greece( I think so, but we have earthquakes all year round) , this subject is very intersting!
I found on the internet how a cyclon is triggered:

http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/cyc/arms.rxml
 
"A cyclone is an area of low pressure around which the winds flow counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. A developing cyclone is typically accompanied by a warm front pushing northward and a cold front pulling southward, marking the leading edges of air masses being wrapped around a center of low pressure, or the center of the cyclone.
A low pressure center is where the pressure has been measured to be the lowest relative to its surroundings. That means, moving in any horizontal direction away from the "Low" will result in an increase in pressure. Low pressure centers also represent the centers of cyclones. "

 :huh2 :huh2 :huh2 :huh2 :huh2 :wall :wall :wall :huh2 :huh2 :-X :-[ :bigcry.gif:

Well , could you give me a simplified explanation of what is going on? What are all these "fronts " >:(     (using ,of course the basic knowledge on barometer ,that I thing so far I have acquired) :wall

  Uh....let me see! A cold front.... Cold dry air (thus heavy) towards a hot moist air(lighter)
Warm .. front...uh...uh...difficult..mmm...may be hot dry air towards cold or hot moist air? :oops I don't know..
Well , I understand that wind has a direction H to Low. Isn't that enough?
ooofff.. A friend of mine asked me "What is the result when we substract the barometric pressure in the wall of a hurricane minus the one on the center of it".

[gcks]

And how does a cyclon cease ?

[Astronuc]

And how does a cyclon cease ?

A cyclone, i.e. typhoon/hurricane ceases when the energy is dissipated and the system moves over land or cooler water.  Over cooler water there is less thermal energy available, and over land, the is essentially no thermal energy available to 'drive' the cyclone.

[Astronuc]

Heat Waves, Hurricanes Predicted for Summer in U.S.

By John Roach
for National Geographic News
May 22, 2003

Summary: Summer weather is notoriously difficult to forecast because there is no jet stream over the United States to stabilize atmospheric conditions. Nonetheless, meteorologists believe there are indications that this year it may be hotter than the recorded average for the southern part of the country while the Gulf and Atlantic Coasts of the U.S. may be battered by more hurricanes than normal. A lot depends on La Niña, the name scientists give to a sustained cooling of surface temperatures of the central and eastern tropical Pacific.

Full Story:
As the season of long days and short nights, barbecues and cold drinks, and lakeshore and beachfront retreats is kicked off this Memorial Day weekend, forecasters train their gaze on charts and graphs as they attempt to predict the fickle summer weather.


"In summer we are not dealing primarily with a jet stream," said Mike Halpert, a meteorologist with the National Oceanic and Atmospheric Administration Climate Prediction Center in Camp Springs, Maryland. "It typically shifts northward into Canada."

The lack of a main jet stream over the United States makes the prediction work of Halpert and his colleagues difficult. In the winter months, the jet stream tracks storms across the country in predictable patterns that are influenced by long-term ocean currents.

"For summertime rainfall there are not any long-term trends to point us one way or another," said Halpert. Instead, unsettled summer weather tends to be dominated by isolated thunderstorms spawned by localized humidity and heat.

The only statement Halpert and his colleagues at the Climate Prediction Center are making about the general summer weather is that it will be hotter than normal from the Southwest eastward across central and southern Texas across the Southeast to Florida.

The reason cited is a "trend tool" that indicates temperatures in the South have been above normal during much of the past ten years, said Halpert. The center does not ascribe the warm trend to global warming, just a long-term trend that they expect to continue.

As for the Northeastern United States, Halpert said that he and his colleagues "don't have a good handle" on the weather forecast. All winter they were calling for warmer weather, but it ended up colder than normal. For this summer they are keeping their mouths shut.

Hurricanes

The one area where climate forecasters do have traction this time of year is hurricane season, which officially begins on June 1. The season does not usually rev up until the late summer and early fall. It officially ends November 30.

For the 2003 season, both the National Oceanic and Atmospheric Administration and the renowned forecast team at Colorado State University in Fort Collins led by atmospheric scientist William Gray are calling for "above normal" levels of activity.

Get ready for Ana, Bill, and Claudette. Watch out for Danny, Erika, and Fabian. Be braced for Grace, Henri, and Isabel. They, along with Juan, Kate, Larry, and perhaps a few other named storms may form in the Atlantic basin.

The NOAA forecast calls for a potential of 11 to 15 named tropical storms and the Colorado State team calls for 12 named storms. Of those, NOAA predicts that 6 to 9 will form into hurricanes, of which 2 to 4 will be classified as major.

The Colorado State team says 8 will become hurricanes, 3 of them intense with sustained winds of 111 miles (179 kilometers) per hour or greater. The long-term average is 9.6 named storms, 5.6 hurricanes, and 2.3 intense hurricanes per year.

The 2002 hurricane season saw 12 named tropical storms, but only 4 hurricanes, and 2 intense hurricanes. The 2003 season promises to be stronger, said Phil Klotzbach, a member of the forecast team at Colorado State University.

"Most importantly, the El Niño that put a damper on last season is gone now," he said. "Right now conditions are about neutral between El Niño and La Niña and it looks like conditions will go towards La Niña this summer, though it is difficult to say."

Additionally, the North Atlantic continues to be warmer than normal as part of a multi-decadal pattern. Klotzbach said that when this pattern existed in the 1950s and 60s, every year except for El Niño-influenced years were more active than normal.

According to the forecast by Klotzbach and his colleagues, there is a 68 percent chance that one of the major hurricanes will make landfall somewhere along the U.S. Atlantic or Gulf coasts.

Halpert, with the Climate Prediction Center, said "we expect to see more storms develop in the Gulf of Mexico and the Atlantic Ocean, but there is no way to say where those storms will go at this stage."

As a result of the more active hurricane season, Halpert says that the Atlantic and Gulf Coast regions should expect a wetter than normal later summer and fall.

La Niña Wildcard

The wildcard for hurricane forecasters is whether or not La Niña forms over the course of the summer. La Niña is characterized by unusually cold temperatures in the equatorial Pacific Ocean as opposed to El Niño's unusually warm temperatures.

"If you have La Niña, hurricane activity will be enhanced even further," said Klotzbach. The weather phenomenon reduces vertical wind shear in the heart of the hurricane development region.

NOAA says there is a 70 percent chance of La Niña forming. If it does, the influence will be most strongly felt next winter when it should result in drier and warmer conditions in the Southeast.

"In winter, patterns are somewhat more predictable. It looks like we will see a La Niña developing over the coming months, so we may be expecting a La Niña-influenced winter," said Halpert.

Hurricane Season 2004 - http://news.nationalgeographic.com/news/2004/11/1130_041130_florida_hurricanes_2004.html

[Astronuc]

New Hurricane-Forecast Tool Debuts (And Just in Time)
By Willie Drye for National Geographic News

With another active hurricane season expected in a few months, meteorologists and insurance companies will have a new forecasting tool to help them predict whether late-season storms will again batter the U.S. coastline.

Researchers at England's University College London have devised a computer model that uses data from midsummer winds to predict the likelihood of hurricanes striking the United States later in the season.

The model was created by scientists at the college's Benfield Hazard Research Centre. The center is sponsored by Benfield, a London-based reinsurance company that is one of the world's largest.

The new model could get a real workout right from the start. Forecasters think a ten-year trend of active hurricane seasons will continue this summer.

William Gray, a pioneer in long-range hurricane forecasting who is based at Colorado State University, thinks seven hurricanes will form in the Atlantic Basin this year. (The region includes the Caribbean and the Gulf of Mexico.) The professor of atmospheric science predicts that three of those storms will be major ones, with winds exceeding 111 miles an hour (179 kilometers an hour).

Gray believes there's a better-than-even chance that one of those intense hurricanes will make landfall somewhere on the U.S. east coast.

Gray also thinks the U.S. Gulf Coast faces a higher-than-usual risk of taking a hit from a major hurricane, although not as high as the Atlantic Coast.

Hurricane season runs from June 1 to November 30.

The computer model developed by University College London researchers analyzes data from July wind patterns from sea level up to about 25,000 feet (about 7,500 meters).

The model predicts whether the winds are forming "steering currents." Such currents would guide hurricanes to the U.S. shores from August through October, when most storms form.

Last summer those steering currents helped shove five hurricanes ashore—four in Florida and one in North Carolina.

During some hurricane seasons, however, the wind currents tend to push storms away from U.S. shores.

The data for the new computer model - which is described in the latest issue of the science journal Nature - is based on July wind patterns from 1950 to 2004.

Mark Saunders, a research climate physicist at University College London, said the computer model is a "breakthrough" in hurricane forecasting that could help the insurance industry minimize financial loses during hurricane season.

"It reduces the financial risk and uncertainty of the hurricane season as a whole," Saunders said.

Insurance companies paid out 23 billion dollars (U.S.) in U.S. damage claims because of the 2004 hurricane season. This year they face the prospect of covering billions of dollars' worth of new claims if more hurricanes come roaring off the ocean this summer.

Since 1950 the annual cost of U.S. hurricane damage, adjusted for today's inflation, has averaged about 5.6 billion dollars (U.S.).

Saunders developed the computer forecasting model with his colleague, Adam Lea. Saunders said their model has a 74 percent accuracy rate in predicting whether a hurricane will make landfall in the U.S. The model does not predict where hurricanes are likely to strike, however.

Still, even knowing that a hurricane landfall is likely somewhere in the United States could give insurers enough warning to protect themselves from a potentially staggering financial hit.�  � If a busy peak season is expected, insurance companies could reduce their possible losses by taking out their own reinsurance with other companies specializing in that kind of coverage, Saunders said.

from http://rl.channel.aol.com/natgeo?id=20050422123909990001 (AOL registration/subscription required).