Is U.S. climate getting more extreme?

By: Dr. Jeff Masters , 1:54 PM GMT on March 13, 2009

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Is the climate in the U.S. getting more extreme? The answer to this question depends upon how one defines "extreme". For example, the number of extreme tornadoes (violent EF-4 and EF-5 twisters) has not increased in recent years. We lack the data to judge whether there has been an increase in severe thunderstorms and hail. There has been a marked increase in Atlantic hurricane activity since 1995 (though the possible contribution of human-caused global warming to this increase is not something hurricane scientists agree upon). Since it is difficult to quantify how severe storms like tornadoes and hurricanes are changing, a better measure of how climate extremes are changing is to look at temperature and precipitation, which are well-measured. NOAA's National Climatic Data Center (NCDC) has developed a Climate Extremes Index to attempt to quantify whether or not the U.S. climate is getting more extreme. The Climate Extremes Index (CEI) is based upon three parameters:

1) Monthly maximum and minimum temperature
2) Daily precipitation
3) Monthly Palmer Drought Severity Index (PDSI)

The temperature data is taken from 1100 stations in the U.S. Historical Climatology Network (USHCN), a network of stations that have a long period of record, with little missing data. The temperature data is corrected for the Urban Heat Island effect, as well as for station and instrument changes. The precipitation data is taken from 1300 National Weather Service Cooperative stations. The Climate Extremes Index defines "much above normal" as the highest 10% of data, "much below normal" as the lowest 10%, and is the average of these five quantities:

1) The sum of (a) percentage of the United States with maximum temperatures much below normal and (b) percentage of the United States with maximum temperatures much above normal.

2) The sum of (a) percentage of the United States with minimum temperatures much below normal and (b) percentage of the United States with minimum temperatures much above normal.

3) The sum of (a) percentage of the United States in severe drought (equivalent to the lowest tenth percentile) based on the Palmer Drought Severity Index (PDSI) and (b) percentage of the United States with severe moisture surplus (equivalent to the highest tenth percentile) based on the PDSI.

4) Twice the value of the percentage of the United States with a much greater than normal proportion of precipitation derived from extreme (equivalent to the highest tenth percentile) 1-day precipitation events.

5) The sum of (a) percentage of the United States with a much greater than normal number of days with precipitation and (b) percentage of the United States with a much greater than normal number of days without precipitation.


Figure 1. The Annual Climate Extremes Index (CEI), updated through 2008, shows that U.S. climate has been getting more extreme since the early 1970s. Image credit: National Climatic Data Center. On average since 1910, 20% of the U.S. has seen extreme conditions in a given year (thick black line).

As summarized by Gleason et al. (2008), the National Climatic Data Center concludes that based on the Climate Extremes Index, the percentage of the U.S. seeing extreme temperatures and precipitation generally increased since the early 1970s. These increases were most pronounced in the summer. No trend in extremes were noted for winter. The annual CEI index plot averaged for all five temperature and precipitation indices (Figure 1) showed that five of the fifteen most extreme years on record occurred since 1997. Shorter-lived periods with high CEI values occurred in the 1930s and 1950s, in association with widespread extreme drought and above-average temperatures. The most extreme year in U.S. history was 1998, with 1934 a close second. The year 1998 was the hottest year in U.S. history, with a record 78% of the U.S. experiencing minimum temperatures much above normal. That year also had a record 23% of the U.S. with much greater than normal precipitation from extreme 1-day precipitation events. The 1934 extreme in CEI was due in large part because of the most widespread drought of the century--a full 52% of the U.S. was affected by severe or extreme drought conditions. That year also saw a record 64% of the U.S. with much above normal maximum temperatures.

The impact of maximum and minimum temperatures on the Climate Extreme Index
It is very interesting to look at the five separate indices that go into the Climate Extremes Index. Today I'll look at temperature, and next week, I'll focus on drought and precipitation. The portion of the U.S. experiencing month-long maximum temperatures either much above normal or much below normal has been about 10% over the past century (black lines in Figure 2). However, over the past decade, about 20-25% of the U.S. has been experiencing monthly maximum temperatures much above normal, and the portion of the U.S. experiencing much colder than normal high temperatures has been near zero. Minimum temperatures show a similar behavior, but have increased more than the maximums (Figure 3). Over the past decade, minimum temperatures much above normal have affected 25-35% of the U.S. This means that the daily range of temperature (difference between minimum and maximum) has decreased over the past decade, which is what global warming says should be happening if greenhouse gases are primarily to blame for the rise in temperatures.

While there have been a few years (1921, 1934) when the portion of the U.S. experiencing much above normal maximum temperatures was greater than anything observed in the past decade, the sustained lack of maximum temperatures much below normal over the past decade is unique. The behavior of minimum temperatures over the past decade is clearly unprecedented--both in the lack of minimum temperatures much below normal, and in the abnormal portion of the U.S. with much above normal minimum temperatures. Remember that these data ARE corrected for the Urban Heat Island effect, so we cannot blame increased urbanization on the increase in temperatures. Recall that the all-time record maximum and minimum temperature data, which I presented in a post in February, are not corrected for the Urban Heat Island Effect, but look very similar to the CEI maximum and minimum temperature trends presented here.

A lot of people have told me that they believe we are experiencing more wild swings of temperature from hot to cold from day to day in recent years, but the CEI data does not answer this question. To my knowledge, a study of this kind has not been done.


Figure 2. The Annual Climate Extremes Index (CEI) for maximum temperature, updated through 2008, shows that 20-25% of U.S. has had maximum temperatures much above normal over the past decade. Image credit: National Climatic Data Center.


Figure 3. The Annual Climate Extremes Index (CEI) for minimum temperature, updated through 2008, shows that 25-35% of U.S. has had minimum temperatures much above normal over the past decade. Image credit: National Climatic Data Center.

References
Gleason, K.L., J.H. Lawrimore, D.H. Levinson, T.R. Karl, and D.J. Karoly, 2008: "A Revised U.S. Climate Extremes Index", J. Climate, 21, 2124-2137.

Annual WeatherDance contest ready for registration!
Armchair forecasters, now's your chance to shine! WeatherDance, based on teams in the men's and women's NCAA basketball tournaments, allows players to predict which team's city will be hotter or colder on game day in each round of the Big Dance. Beginning today, players can make their forecasts at the Weather Dance Web site at: www.weatherdance.org. The site will be updated with cities promptly after NCAA seeding announcements. First round Weather Dance selections must be entered by 11:59 p.m. EDT Wednesday, March 18.

"Officially, Weather Dance began as a class project to get students involved in weather forecasting, but we kept it around because it got popular. People think they can do better forecasting than the meteorologists. Well, here's their shot!" said Perry Samson, WeatherDance creator, co-founder of the The Weather Underground, Inc., and Professor in the Department of Atmospheric, Oceanic and Space Sciences at the University of Michigan.

This is the fifth year for the game. Last year more than 2,000 people played. Most play merely for the thrill, but many K-12 science teachers involve their classes as part of meteorology units. The winning teacher will receive an expense-paid trip to join the Texas Tech/University of Michigan Storm Chasing team this spring for a day of tornado chasing in Tornado Alley. Other winners will receive a Weather Underground umbrella, "Extreme Weather" mugs, or a copy of the book "Extreme Weather," by Christopher C. Burt.

I'll talk about drought and precipitation trends in my next post, Monday or Tuesday.

Jeff Masters

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172. GBlet
I keep this with my tornado supplies. I also dip my own matches in nail polish and store them there as well.
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That's a excellent point on Inland winds.

That's one definite reason the NHC is going with the Inland Hurricane Warning Graphic.
A good idea all around.

Canes are NOT just a Coastal Event ..as Ike showed many States thru the USA inland last summer.
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170. GBlet
KEH, I keep dried onions, garlic powder and bacon bits in a "paint can" I purchased from a craft store.
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Quoting homelesswanderer:
I know this opinion hasnt been popular in the past here but I think the idea of "run from the water,hide from the wind is a bad idea. Please RUN FROM IT ALL!! Unfortunately I'm not computer literate enough to post pictures of the wind damage from Rita. But I'll be working on that. It was horrendous to say the least. People died from falling trees in Angelina County, over a hundred miles inland. And several places in between.
I'm not trying to argue with anyone. Just wish people to be aware.


The conditions for Rita in Kenner were almost identical to Hurricane Cindy.There really wasn't that much damage though because Katrina had alrady wiped out anything that could be knocked down in 55-70mph wind.
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I know this opinion hasnt been popular in the past here but I think the idea of "run from the water,hide from the wind is a bad idea. Please RUN FROM IT ALL!! Unfortunately I'm not computer literate enough to post pictures of the wind damage from Rita. But I'll be working on that. It was horrendous to say the least. People died from falling trees in Angelina County, over a hundred miles inland. And several places in between.
I'm not trying to argue with anyone. Just wish people to be aware.
Member Since: August 15, 2008 Posts: 10 Comments: 3665
We have a Yamaha 230 SX HO(big boat),
We will tie it to the house again,
Like we did in Hurricane Katrina and Hurricane Gustav just incase.
I know I should be scared after pretty much seeing almost every video on youtube of Hurricanes/Storm Surge, Tsunamis, and flooding.
Im not near a levee so there should not be any current if a levee were to breach.It would simply just rise, maybe quick but with not much of a current.
If that unfortunate event of a levee breach were to occur in NJP we would get on the roof quickly, and get in the boat thats tied to the House and leave and rescue as many people as possible on the way out.
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Whenever I evacuated, and the storm missed, I treated it like a shake-down cruise. See what worked, what didn't. I know I want to rework some minor things this year. I used to have my family photos all together in a brief case, somehow, I have them scattered in a million different locations. I need to fix that.
And need to find recipes to make canned veggies more palatable!!!
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Surge,..and the Hurricane Blowing outside...,always a Bad way to Fly..

Leave and watch it on TV.

If it misses,you out only a few days inconvenience.
The other choice..
Wrong in every aspect.

melwerle and fam made the right and choice and heeded her Local Emg Mgt and iz living proof of that.

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Not scared of water? I would like to know exact numbers of how many folks die from the wind related injuries versus FLOODING.

I would be SOOOO gone from here - i am VERY afraid of the water and I sail all the time...folks who have been here long enough should know - hide from the wind, run from the water...

Patrap - I believe that is the same video that you posted last year that made my hubby decide to pack up during a threat that might have been coming our way...no way we were drowning. Keep posting it through the season for any knucklehead who says they are going to get a lifejacket and stay.

Melissa
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This video gives a deep insight of Cyclogenesis

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Man Scared of Water saying..,

"Man..I made a Big Mistake"....

In his own Words.

Aug 29,th 2005 Chalmette,La.


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Futuremet - Thanks!


Quoting SevereHurricane:
After a Hurricane is different reguarding canned goods,
We will stay for anything.
Im not scared of water.
Yep, we were talking about hurricane supplies that are canned veggies - I avoid canned veggies otherwise.
I am not sure what you mean by 'Im not scared of water' You have been reading this blog long enough to know better than that.
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Thanks Future!

Im going to be using that.
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Quoting BahaHurican:
To give credit to the writer of the article, they didn't identify the cause of the global warming, just that the warming trend is influencing birds' migration patterns.


True. I guess I have been conditioned to the usual blame everything on the AGW press...
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I've got great news!

I just found this new weather educational youtube channel. The author of the videos is actually a genuine atmospheric scientist professional. I strongly recommend watching his videos to augment your knowledge about atmospheric rudiments

Link
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Quoting BahaHurican:
After a hurricane, it's likely here that we will have downed fruit of some kind in our yard - mangos, sapodillas, avocados etc. Unfortunately what comes down is usually not terribly edible. . . . but we are only looking at a small scale of fruit, not what yr family would have available.



After a Hurricane is different reguarding canned goods,
We will stay for anything.
Im not scared of water.
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Quoting SevereHurricane:


I don't have to worry about canned veggies or friut. My family owns a Produce Company,
But I usually take it for granite...
After a hurricane, it's likely here that we will have downed fruit of some kind in our yard - mangos, sapodillas, avocados etc. Unfortunately what comes down is usually not terribly edible. . . . but we are only looking at a small scale of fruit, not what yr family would have available.

Member Since: October 25, 2005 Posts: 19 Comments: 21169
Quoting BahaHurican:
I realized this myself last year. I usually stock up on meats and beans, with only corn as a possible veggie. Last year I tried to put some italian beans, green peas, and so on there. But man, do I HATE canned veggies. . . . lol


I don't have to worry about canned veggies or friut. My family owns a Produce Company,
But I usually take it for granite...
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154. HTV
Quoting BahaHurican:
To give credit to the writer of the article, they didn't identify the cause of the global warming, just that the warming trend is influencing birds' migration patterns.

Living here in SE Texas for 40+ years I have noticed over the years less robins coming down here usually around the third week of January. Used to be yards would be full of robins dining on insects fattening up for there flight back North to mate. This year I saw a few, last year none. Over the last several years there were a couple where we had a significant migration . Seems to correlate to the amount of snow pack north of us. Used to be like clock work and we knew Spring wad just around the corner. Climate change, yes. Global Warming, not convinced.
Quoting BahaHurican:
I realized this myself last year. I usually stock up on meats and beans, with only corn as a possible veggie. Last year I tried to put some italian beans, green peas, and so on there. But man, do I HATE canned veggies. . . . lol
I have been trying to come up with ways to make the canned veggies more palatable. I am thinking 3 Bean Salad. Good way to spice up the beans, I think. If anyone else can think of a recipe for 'hurricane shelf' veggies, to make them more palatable - I would certainly like to know.
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Quoting atmoaggie:


Wow, the Beaumont Emptyprise actually published something. I remember looking at that paper 10 years ago. You could see straight through it as it was folded to sell...

Changes over 25 years do not constitute any proof of AGW, only changing climate (it is always changing)
To give credit to the writer of the article, they didn't identify the cause of the global warming, just that the warming trend is influencing birds' migration patterns.
Member Since: October 25, 2005 Posts: 19 Comments: 21169
Quoting homelesswanderer:
Global warming, hurricanes alter birdwatching season
Like the canary to the coal miner, the purple finch might be a warning sign of climate changes to come in Southeast Texas.
Link

Thought this was interesting. Maybe we could learn something from our feathered friends.


Wow, the Beaumont Emptyprise actually published something. I remember looking at that paper 10 years ago. You could see straight through it as it was folded to sell...

Changes over 25 years do not constitute any proof of AGW, only changing climate (it is always changing)
Member Since: Posts: Comments:
Global warming, hurricanes alter birdwatching season
Like the canary to the coal miner, the purple finch might be a warning sign of climate changes to come in Southeast Texas.
Link

Thought this was interesting. Maybe we could learn something from our feathered friends.
Member Since: August 15, 2008 Posts: 10 Comments: 3665
AMEN!! "Apocalypse-induced Misanthropic Environmental nervousness".
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Quoting presslord:
Link

interesting
Very. Especially this: "Through March 12, 2009, the Southern Hemisphere ACE is about half of what's expected in a normal year, with a multitude of very weak, short-lived hurricanes." Sounds familiar? I think we've done a lot to examine NATL data of late, including the reanalysis project mention in #105, but I'd really like to see what could be made of a global pattern of data in, say, 50 years.
Member Since: October 25, 2005 Posts: 19 Comments: 21169
Quoting StormW:
Are you a High School student with a strong interest in weather (or in a related physical/earth science)? Then you may want to check out NOAA's (National Oceanic and Atmospheric Administration) NCAS (National Center for Atmospheric Sciences) High School Weather Camp.

For more information, please visit our website WCFLAMS
and click on the Chapter News tab.

Thanks!

T.F. "Storm" Walsh III
West Central Florida AMS Chapter (Webmaster)
Hiya Storm. Good to see u on.

Any thoughts on the upcoming season?
Member Since: October 25, 2005 Posts: 19 Comments: 21169
Quoting RTLSNK:
46*F in Macon, Ga this morning, storm system slowly headed our way. Have recently discovered photographic proof of Global Warming. Cannot verify its scientific accuracy.

Now THIS is change I can believe in . . .
Member Since: October 25, 2005 Posts: 19 Comments: 21169
Quoting AussieStorm:
It's over: Victorian fires contained
Article from: AAP

March 14, 2009 12:15pm

All of Victoria's bushfires have now been contained.
Emergency services said the Wilsons Promontory Cathedral fire was finally contained at 10am (AEDT) today, ending the last major bushfire that had been threatening Victoria since Black Saturday.

Australia's worst natural disaster has claimed the lives of 210 Victorians, more than 2000 homes and burnt 421,670 hectares of public and private land since starting on February 7. "
I'm glad to see this. This was such a disastrous year for southern Australia.
Member Since: October 25, 2005 Posts: 19 Comments: 21169
ON the effects of air pollution on health, I've been wondering if some of the increase seen in chronic respiratory illnesses such as asthma is related to increased rates of certain kinds of air pollutants, especially in cities.
Member Since: October 25, 2005 Posts: 19 Comments: 21169
141. Skyepony (Mod)
~12,000 died in the great London smog of 1952.
Member Since: August 10, 2005 Posts: 161 Comments: 37158
Quoting floridafisherman:
Care to look up the life expectancy in the US since we started burning fossil fuels? The answer does not fit your mold.

thats a pretty stupid assumption. we have higher life expectancys because of better medical care. and yes, things like smoke, smog, and other pollutant CAN KILL! apparrently, despite your attempt at intellect, you have overlooked simple weather and health facts. anything besides air that enters your lungs is a contaminate.

do you need to be provided a link describing the health side effects of smog, smoke, and other pollutants?
Better example of life expectancies re: fossil fuel pollution is a place like London, where the smog was so bad at the height of the coal-burning revolution that it DID make people sick and lower life expectancies.
Member Since: October 25, 2005 Posts: 19 Comments: 21169
Quoting KEHCharleston:
RE:14. Patrap
I had a reason to dip into my hurricane shelf's canned goods. (fridge died). What I found was that though I had plenty canned fruit, soups, tuna, chili, spaghetti meatballs (yuck!) - I did not have much in the way of veggies. I normally cook either fresh or frozen veggies, and seldom spend any time at the grocery aisle for canned veggies.
It was an eye-opening experience to live a few days on supplies from my hurricane shelf. (I recommend to everyone, to give it a try). I have since added canned corn, carrots, beets, and peas.
I realized this myself last year. I usually stock up on meats and beans, with only corn as a possible veggie. Last year I tried to put some italian beans, green peas, and so on there. But man, do I HATE canned veggies. . . . lol
Member Since: October 25, 2005 Posts: 19 Comments: 21169

wunderground.com - Google News
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Link

interesting
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Two more Florida counties have passed the 700 mark today. Miami-Dade and Okeechobee.
There's 4 or 5 more counties ready to turn soon.
I think you could say southern FL is in a serious drought:





Member Since: October 29, 2007 Posts: 135 Comments: 46052
134. HTV
Anyone buying Dr. Hanson and NASA predictions of a +1.5 Nino come Mid-Summer? From what I've read here and other sites most feel a neutral to slightly positive ENSO.
Seasonal forcasting is not a specialty of mine but its been quite a while since ive seen the tropical atlantic this cool i.e; MDR region and of the african coast.Having said that things can change in a hurry so we'll see what happens during the next 2-4 months.

Adrian
Member Since: May 14, 2006 Posts: 8 Comments: 13621
Didn't really add any new content to the blog. Spruced it up a little though ;) Appreciate any comments. Surfmom looks like lady in red is getting ready to have some purple flashes, can't be good. We really need the rain.
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Just wanted to inform everyone that I have posted the first blog entry on the CCHS Weather Center site. In the first blog entry, I discuss the severe drought and potentially bad fire season ahead for Florida. Would love to see some comments on my blog. You'll just need to register as a member on my site in order to comment. On the Home page, you will find a tool that you can use to easily register for my site. Once you do that, then you'll be a FREE registered member on the CCHS Weather Center site. Thanks.
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Isolated Showers Space/Treasure Coasts
Through early afternoon, isolated showers will move north to northwest over the coastal waters from Cape Canaveral to Jupiter Inlet. A few showers will affect adjacent coastal sections and produce a brief period of rain.

$$

Radar at 1048 am showed that most of the shower activity was over the nearshore Atlantic waters. A few stray showers were affecting land areas from Melbourne to Vero Beach and St. Lucie county. The showers were moving nearly parallel to the coast, so the bulk of the rainfall will remain over the water. Additionally, drier air above the surface will gradually mix down during daytime heating, which should cause the showers over land to dissipate by early afternoon.

Member Since: October 29, 2007 Posts: 135 Comments: 46052
It's raining again lol
Member Since: August 12, 2007 Posts: 2 Comments: 2838
128. Skyepony (Mod)
Big AG has been the root of many evils, from the dust bowl, poisoning whole towns & even some countries (Columbia), excessive use of oil, contributing to pollution & global warming, strip mining, all to feed us high fructose corn syrup & other such substances that is most's new diet that are contributing to many health problems like diabetes & heart problems.. Now a bill has been introduced that would effectively put the small farmer out of business & end farmers markets as well as the grow local movement. Possibly end organics all together, since big ag would be all that is left with no compition, they wouldn't need to offer non hormone inhanced milk, non GMOed that withstands spraying with round up & non-cloned meat. This would seriously reduce our freedom of food choices unless you grow your own. If you sold it the fine would be $1,000,000. To quickly fire off a prewritten letter or one of your own, to your rep, go here & put in your zip code..
Member Since: August 10, 2005 Posts: 161 Comments: 37158
Check out the little swirl heading towards pensacola. Link
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RTLSNK- You live in Macon, Georgia too?! So do I! How did ya like that snow a couple weeks ago?
Once every 7 or 8 years. Of course just a week
after the snow temps went back up to the mid-80's. And I am also waiting for the storm that's supposed to make rain all the way through monday.. how miserable..
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images

Click Here For Myspace Graphics at GraphicsHunt.com - Myspace Layouts

The water problem has grow as Skyepony points out. Link
Member Since: June 12, 2005 Posts: 6 Comments: 8184
Wow we actually got some rain showers here in st lucie overnight and a few earlier this morning.
But it was only .06 of an inch.
Member Since: August 12, 2007 Posts: 2 Comments: 2838
From Dr. Masters Oct 27,2008 Blog entry


Heavy Internet weather
A record six consecutive tropical storms and hurricanes pounded the U.S. this hurricane season, creating some serious "Internet weather"--a flood of high Internet traffic. On September 12, as Hurricane Ike bore down on the Texas coast, our popular weather web site wunderground.com recorded its busiest day ever--28 million page views, triple its normal traffic. We vaulted from a ranking of 107th to 75th on the Quantcast, Inc. list of most-trafficked web sites in September, thanks to the huge amount of web traffic created by Tropical Storm Fay, Hurricane Gustav, Hurricane Hanna, and Hurricane Ike. As hurricane season winds down, so has our ranking--we're down to 138th on the list of most-trafficked web sites. The ranking will rise again as we enter winter and winter storms begin pounding our population centers.



Traffic on my blog averages about 50,000 page views per day. The record was on September 12, when 800,000 page views were recorded. Thanks for your support!

I'll have a new blog entry on Wednesday.

Jeff Masters
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122. HTV
You might want to bookmark this sight.
allmyfaves.com
WU is listed here also

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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