A weakened Igor bears down on Bermuda; 94L likely to develop

By: Dr. Jeff Masters , 2:17 PM GMT on September 19, 2010

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Hurricane Igor is closing in on Bermuda, but the hurricane's eyewall has collapsed, weakening Igor into a large but still dangerous Category 1 hurricane with 85 mph winds. Winds in Bermuda are rising, and exceeded tropical storm-force for the first time at 9:55 am AST this morning. Bermuda radar shows the island is now embedded in one of the main heavy rains bands of Igor, and is experiencing heavy rain and high winds. As of 11 am AST local time, winds at the Bermuda Airport were sustained at 46 mph, gusting to 63 mph. Winds will continue to rise today as the storm's core approaches. Hurricane force winds should arrive at the island between 4 - 8pm AST today, and last for 4 - 8 hours. The Bermuda Weather Service is calling for Category 1 hurricane conditions with waves of 25 - 45 feet affecting the island's offshore waters during the peak of the storm. Buildings in Bermuda are some of the best-constructed in the world, and are generally located at higher elevations out of storm surge zones; thus damage on the island may be just a few million dollars. With its eyewall gone, it is highly unlikely that Igor will be able to intensify before making landfall.


Figure 1. Hurricane Igor as seen from a "radar in space" microwave instrument on the polar-orbiting F-16 satellite at 7:36 am AST Sunday September 19, 2010. The eyewall has mostly collapsed, leaving just one fragment behind on the northwest side of Igor's center. Image credit: Navy Research Lab, Monterey.

94L
A tropical wave (Invest 94L) off the coast of Africa, a few hundred miles west of the Cape Verdes Islands, has developed a broad surface circulation and is threat to develop into a tropical depression. The wave is under a low 5 - 10 knots of wind shear, and is over warm 28°C waters. Dry air from the Sahara is interfering with development, and 94L only has a modest amount of heavy thunderstorm activity associated with it. Shear is expected to be low for the next four days, and all of the major models develop 94L into a tropical depression 1 - 3 days from now. NHC is giving the wave a 70% of developing into a tropical depression by Tuesday. With the exception of the NOGAPS model, the models predict that 94L will move northwestward out to sea.


Figure 2. Morning satellite image of Invest 94L.

Julia
Tropical Storm Julia is being ripped apart by wind shear from Igor, and will likely dissipate on Monday or Tuesday.

Typhoon Fanapi
Typhoon Fanapi made landfall in northern Taiwan early Sunday morning local time as a Category 3 storm with 120 mph winds. Fanapi killed three people on the island, and brought rains of up to 690 mm (27.2 inches) to mountainous regions in the interior. Fanapi is the strongest typhoon so far this year, in what has been an exceptionally quiet Western Pacific typhoon season. The previous strongest typhoon this season was Typhoon Kompasu, a low-end Category 3 storm with 115 mph winds that hit South Korea in early September. As seen on Taiwan radar, Fanapi has crossed over Taiwan and is now in the Taiwan Strait between the island and mainland China. Fanapi is expected to hit China about 150 miles east-northeast of Hong Kong on Monday, as a Category 1 typhoon.


Figure 3. Typhoon Fanapi at landfall in Taiwan at 7:10 local time on September 19, 2010. Image credit: Taiwan Central Weather Bureau.

Elsewhere in the tropics
In many recent runs, the NOGAPS and GFS models have been predicting development of a strong tropical disturbance or tropical depression in the Central Caribbean 6 - 9 days from now. However, the timing, location, and track of the potential development have been inconsistent from run to run. We should merely take note of the fact that these models predict that the Caribbean will be ripe for tropical storm development late this week and early next week, and not put much faith in the specifics of these highly unreliable long-range forecasts.

I'll have a new post on Monday.

Jeff Masters

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Post 198
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Quoting KanKunKid:


Tossing a coin into the air has a finite cyclic outcome of only 2, heads or tails. The outcome is dependent on few factors, the height of the toss, the spin induced, the size and weight of the coin, any wind present and the height at which the coin was caught. In any scenario, it will only be heads or tails. In this case, the law of averages can be brought to bear because, as you pointed out, there is a sufficient data base to refer to for historical data. Now, imagine a coin with 100000 faces, an unlimited amount of spin and height and an undetermined height to catch it. With only a tiny fraction of a data base to pull from, not all scenarios have been run, in fact, the unknown scenarios far outnumber the known, how can it actually be said to be average when of the amount of time man has been on earth and recording history, we have only gathered (incomplete) data for 1/600th of it? It's also interesting to note, that unlike the face of a coin, each scenario has a different outcome with different data fields as well, so even it a scenario repeats a certain portion of a previous scenario, it is almost certain not to behave exactly as the other scenario.
That's why the dynamical models perform better. They take the existing conditions and go from there.


thats where we are differing. Odds are not used to predict that there will be a hurricane in any area. They are not a guarantee. The stat models are used to predict where a storm will go, that is why they dont work. odds should be used as a general guide that it has been a while since the last storm came close, therefore, it is more likely that it will happen sooner than later. But it is not used to predict that it WILL happen.
That is why I dont think we are talking about the same thing.

In a hudnred years, you will be able to use statistics to generally say that there is a hurricane in an area once every 50 years. But they will never be used to predict any single event
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216. Relix
Models stick to 94L going fishing. I just don't buy it yet I mean...



How!?!?
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Quoting BioChemist:


I am pretty sure that is what I tended to in my last post.. you are right
lol.
You and I were typing about the same thought at the same time.

Plus, the objective surface wind speed data thing...
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Quoting PalmBeachWeather:
Knowing a little about tropical weather.I now come here to quietly laugh at the inane posts I see when the (non-experts) are here..
The non-experts have already chased, ridiculed, made fools of themselves, and totally have begun the ruin of this site that I used to love. I know names, but I will not post those names that in this last week have made one of the most knowledgeble poster here run away from the immaturity that has surfaced.
Maybe I will post names, I am so pissed at a few of you that I cannot believe you have or trying to ruin this wonderful site.
No, I won't post names, You know whom you are...and I will never forget you immature people. My 3rd grade nephew has more grownup qualities than you. I will watch the"marked" posters and when I see you, I am out for you.How dare you ...

Don't let the bad apples ruin the bunch. Yes it is sad we lost storm but we will persevere. Plenty of good knowledgeable posters left to make this a good source of information. A suggestion would be to set your filter to above average posters and you dont have to trudge thru so much garbage. Of course you will miss out on some laughs from the not so hot posters.
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Statistically speaking. ;)
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Quoting BioChemist:



I see your point. The act of odds turning out one way does not affect the odds of the next event taking place... or does it?
If you toss a quarter and it lands heads 20 times in a row, even though the odds of that occuring once is 50%, the odds of it happening 20 times in a row is much much less than that.
Therefore, it is much more likely that the next toss would land tails.

My problem with the overdue, and due thing with Hurricanes, is we have had only a hundred or so years of accurate records. When you are dealing with frequencies a tenth or less of the total sample, the trend has not fully worked its self out yet.
If you say, you should get hit, ten times every hundred years... but there has only been a hundred samples. Therefore, there should be a greater sample before you can safely say what the odds are for that period of time.

Very confusing....


Watch out you are revealing that you have a scientific background.

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Quoting plywoodstatenative:
What I ask is this, how it is that this late in the season we are seeing storms developing off the coast of Africa. If I am right it was last week when the statement was made that Julia would be the last system to develop in that area due to the Troughs that are pushing off the east coast. If that was true, why is 94L getting that shape?


CV season, just like hurricane season does not have a set start and end date. It usually ends around Oct 1 =/-.
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I just want to let any Texans on here know that the flash flood warning for the area of Brownsville, TX has been lifted.

However, now there is a flash flood warning and a special marine advisory in place for the area just south of Corpus Christi, TX.

There is a very heavy long and fairly wide rain band passing over this area, please be careful everyone.
Member Since: September 7, 2010 Posts: 0 Comments: 138
What I ask is this, how it is that this late in the season we are seeing storms developing off the coast of Africa. If I am right it was last week when the statement was made that Julia would be the last system to develop in that area due to the Troughs that are pushing off the east coast. If that was true, why is 94L getting that shape?
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Quoting MiamiHurricanes09:
Both TAFB and SAB have 94L a T# of 1.5 so that would be sufficient to upgrade it to a 30mph TD. I assume that the reason that the NHC is backing off is because the circulation is a bit elongated as stated in the Tropical Weather Outlook:

"BUT THE CIRCULATION OF THE LOW APPEARS SOMEWHAT ELONGATED AT THIS TIME."


Slightly elongated, yes...but consolidating. 850mb vorticity is increasing around a more or less central spot. Something to watch, at any rate...
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Quoting AllBoardedUp:
Patrap had a link to an article on why New Orleans had to be rebuilt. It is an eye opener. Maybe he can find it again if anyone is interested.

This is the article: http://www.indiadivine.org/audarya/hinduism-forum/202487-new-orleans-geopolitical-prize.html
(Odd that the original author has taken it down and this Hindu-page is the only full version I could find...but, same words.)
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Quoting DestinJeff:


the classic coin toss probability exercise.

an exercise in mutually exclusive events and outcomes. each flip has zero impact on the probability outcome for the subsequent flips.
Rosencrantz and Guildenstern are dead! Good to see ya DJ!
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Quoting TropicalAnalystwx13:
You know, as crazy as it sounds, I miss being in hurricanes. I used to live on the NC coast and we had Floyd, I wasn't alive for Fran. We also had storms like Isabel (2003) and Ophelia (2005). It was actually kind of fun, and we had close calls sometimes.

Good times, Good times. lol.


When we first moved to La, I looked forward to hurricane season because I had never experienced one. Now that we've "experienced" Katrina, Rita(really bad and expensive times here), Gustav and Ike, all up close and personal, I completely dread hurricane season.

Point being: There's not one dang thing fun about them unless you just enjoy getting your stuff scattered and your life turned upside down for a while each time.

BUT, I will be the first to admit they are fascinating and awesome examples of Momma Nature in a very bad mood.
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Quoting cat5hurricane:
Waves are large & very long over down in Isle of Palms, SC this morning. Surf's up

I went to check out the Windjammer webcam (Isle of Palms, SC) and no live feed. As the website states - this is probably the last thing that the cam saw on 8/15:


In any case the Folly Wash Out Cam is up and running.
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Quoting GBguy88:


I remember being a young kid and having the authorities go door to door telling people they had to evacuate, and if they refused, the officers would say, "Alright, suit yourself, but we'll need your social security number and next of kin written on your arm in permanent marker." That usually gets the message through to people, regardless of your age.


And then they live for the excitement of an evacuation. We've stayed through the hurricanes (no choice, told to stay because south of us is evacuated first and we would be caught on the road). My kids loved the hurricanes and then loved the evacuation to get to where we would have a/c.
Member Since: August 22, 2009 Posts: 0 Comments: 3113
Quoting aislinnpaps:


I tend to think of it as rolling the dice. There are probabilities for how many times you'll roll a seven or a three, but each time is it's own chance of what will fall.


That is what I was trying to get across
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94 L IS A go ...

Eastern Atlantic 1145 utc

Watched it for hours and noticed a few things about 94 L (baby lisa):

1) has broad 3-5 degree (>100mi) diameter ccw circulation (has had eye for hours)

2) 18+ hours of outflow to N and E in 4 waves that has encroached on the SAL (upper divergence) and stretches back towards N Africa

3) bridging arm to SE connecting it to African monsoon wave (more moisture in bound now)

4) embedded in broad area of ccw rotation between SAL going WSW and area either side of 10N tween 30-40W going ENE (lower convergence) Earlier views at CIMSS (choose 'I' on map) distinctly show lower spiral structure and bridge growth. Current view from Floater show increasing outflow beginning to cover the tightening lower level spiral.

5) Post on last blog gave ADT 1.5 over 18 hours to 600z. Development has broadened since then with outflow almost covering central structure.

Dry air is a threat BUT:
- CIMSS (and other views) show Julia's wake is now due west of 94L. I+J outflow can also be seen still entering CIMSS view and dropping wet on the maybe-not so-dry layer - that outflow back along Julia's path and east has been present for days.
- Trend of center is WSW (visible: eye was above 15 now almost at 15) and going WSW along edge of SAL/dry air so 94L doesn't start off like a fish in fact this little puppy might just grow into a dog that will hunt.
- The current WSW motion is also a direct path to 29 and 30C SSTs by tomorrow.

Tropical depression now or later today at least.
This year if a storm can spin, outflow and make spirals it's likely to crank right up if it's below 15 N - just like all the other 'surprises'.
Oh, and the 2d storm in likely next CV pair coming off the coast soon. Check the CIMSS views - #2 is bigger than 94 L and started the flow back east along 10N...


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190. srada
Quoting Bordonaro:

Anyone in their right mind would not want to go through a major hurricane.

When winds exceed 110MPH they roar at 95 decibels. At 140MPH, they roar at an almost deafening 130 decibels. Winds sustained over 100MPH will do serious damage to most American made structures. Then you're stuck in the elements with no where to go!!

I have seen a strong TS & a weak Hurricane. The wind gust to over 100MPH almost through me through a glass door, I made it inside in the knick of time, will milliseconds to spare. Several 50' fully grown maple tree bowed its top and touched the ground. Amazingly they did not snap in half!!


I can say the worst storm I have ever been in was Hugo which past to our south..I was a little girl then but those winds sounded like a train was coming through our living room and we by far didnt even get the worst of that storm in NC..I have been through CAT 3s at the most and they have never been able to touch Hugo in the wind sound..that storm was a whole entity of its own..
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Quoting KanKunKid:


Weather isn't average.


True, but do you discount Climatology altogether? I don't. But, yes, current patterns can trump climatology.




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Quoting DestinJeff:


the classic coin toss probability exercise.

an exercise in mutually exclusive events and outcomes. each flip has zero impact on the probability outcome for the subsequent flips.


I tend to think of it as rolling the dice. There are probabilities for how many times you'll roll a seven or a three, but each time is it's own chance of what will fall.
Member Since: August 22, 2009 Posts: 0 Comments: 3113
94L:

Click for full image and loop

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Quoting atmoaggie:
Yet, in this case, some of the statistics are based on questionable data. A revisit period in a place we have only been inhabiting for ~100 years and having good observational data as far back as regular hurricane hunter flights has the potential to be skewed in the direction of the last ~50 years. (though, I think we know some much more about the surface winds after SFMR started)

Plus, we picked a tough variable to use for these comparisons. Surface winds are something we didn't ever measure by HH before SFMR. Surface winds are attenuated on land, and not consistently, by differing land cover types upwind, so surface wind measures by land-based sites are, umm, "cloudy". Truly, before QuikScat and SFMR, we could only reconstruct surface wind speeds at landfall through wind loading on man made structures and destruction.

If you wanted to pick a variable to compare one hurricane to another that would cause the most confusion, the most difficulty in objective measurement, wind speed might be it.


I am pretty sure that is what I tended to in my last post.. you are right
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Quoting Neapolitan:


I'd put money on it...if not even TS Lisa.
Both TAFB and SAB have 94L a T# of 1.5 so that would be sufficient to upgrade it to a 30mph TD. I assume that the reason that the NHC is backing off is because the circulation is a bit elongated as stated in the Tropical Weather Outlook:

"BUT THE CIRCULATION OF THE LOW APPEARS SOMEWHAT ELONGATED AT THIS TIME."
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With 94L moving more NW, the Cape Verde season with respect to storms hitting the U.S. should be just about out of the way. The disturbance leaving Africa at around 9N latitude is the only remaining possible eastern Atlantic system threat to the U.S. this season IMO. Anything else will be have to come from the Caribbean/Gulf or be home grown. The disturbance in the eastern Caribbean may be interesting to watch.
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Quoting divdog:
absolutely astounds me when people make comments like that. they have either never been thru a major or have some screws loose. Just the wrong thing to say. Not even funny in a joking sense.

Anyone in their right mind would not want to go through a major hurricane.

When winds exceed 110MPH they roar at 95 decibels. At 140MPH, they roar at an almost deafening 130 decibels. Winds sustained over 100MPH will do serious damage to most American made structures. Then you're stuck in the elements with no where to go!!

I have seen a strong TS & a weak Hurricane. The wind gust to over 100MPH almost through me through a glass door, I made it inside in the knick of time, will milliseconds to spare. Several 50' fully grown maple tree bowed their tops and touched the ground. Amazingly they did not snap in half!!
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Quoting BioChemist:


I think you mean west? right?

Thats what that Miami education will afford you :)

Gainesville, is where its at


Ouch! Is that jealousy about the University of Miami passing UF in the rankings (America's Best Colleges- US NEWS & World Report) this year to become the highest-rated college in the state of Florida?
:P
(I'm just messing with you- UF is a fantastic college)
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Quoting StormJunkie:


Ahhh, how press would love you.

KEH, Have been wondering if the shear size of Igor will cause wave heights to be as large as they were with Earl.


Good morning -

Yea, since 9/15 the Edisto Buoy has gone from 1.5 to 8 foot. I did not track Earl at Edisto Buoy. But in anycase, rip currents will be treacherous. Not a good weekend to put one's tootsies in the Atlantic
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Quoting BioChemist:


Statistics and odds will always hold true... on the long term
Just because you are due, does not mean it will happen. But over time, it will always prove to be the case.
I think its a good tool to use to keep the public informed and prepared for a Hurricane. Its a good thing to discuss
Yet, in this case, some of the statistics are based on questionable data. A revisit period in a place we have only been inhabiting for ~100 years and having good observational data as far back as regular hurricane hunter flights has the potential to be skewed in the direction of the last ~50 years. (though, I think we know some much more about the surface winds after SFMR started)

Plus, we picked a tough variable to use for these comparisons. Surface winds are something we didn't ever measure by HH before SFMR. Surface winds are attenuated on land, and not consistently, by differing land cover types upwind, so surface wind measures by land-based sites are, umm, "cloudy". Truly, before QuikScat and SFMR, we could only reconstruct surface wind speeds at landfall through wind loading on man made structures and destruction.

If you wanted to pick a variable to compare one hurricane to another that would cause the most confusion, the most difficulty in objective measurement, wind speed might be it.
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Quoting divdog:
absolutely astounds me when people make comments like that. they have either never been thru a major or have some screws loose. Just the wrong thing to say. Not even funny in a joking sense.


Divdog,
He's 13 years old. He's still at the age where they 'are' exciting. When he owns a house or has a family he'll look at them a little differently.
Member Since: August 22, 2009 Posts: 0 Comments: 3113
Quoting DestinJeff:


But it has a tendency to induce a certain expectation of outcome. Passage of time simply does not increase likelihood of a strike.

And when a particular location gets an inordinate amount of strikes, thereby rendering itself "not due", the argument becomes that it is a "magnet" for hurricane strikes.




I see your point. The act of odds turning out one way does not affect the odds of the next event taking place... or does it?
If you toss a quarter and it lands heads 20 times in a row, even though the odds of that occuring once is 50%, the odds of it happening 20 times in a row is much much less than that.
Therefore, it is much more likely that the next toss would land tails.

My problem with the overdue, and due thing with Hurricanes, is we have had only a hundred or so years of accurate records. When you are dealing with frequencies a tenth or less of the total sample, the trend has not fully worked its self out yet.
If you say, you should get hit, ten times every hundred years... but there has only been a hundred samples. Therefore, there should be a greater sample before you can safely say what the odds are for that period of time.

Very confusing....
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Quoting MiamiHurricanes09:
TD by tonight...? Maybe.


I'd put money on it...if not even TS Lisa.
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171. Mikla
A good site to track potential TC formation is here.

For 94L, go here and you can look at various info, including models.
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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.