Bonnie barely alive

By: Dr. Jeff Masters , 12:58 PM GMT on July 24, 2010

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Tropical Depression Bonnie is barely clinging to life. Wind shear of 25 knots and dry air from an upper-level low pressure system over the Gulf of Mexico are taking their toll on Bonnie, which is now just a swirl of low clouds accompanied by a small clump of heavy thunderstorms on the north side of the center of circulation. These thunderstorms are now visible on New Orleans long range radar, and will arrive in coastal Louisiana early this afternoon, well ahead of the center. The Hurricane Hunters are in Bonnie, and have found a much weaker storm with top winds of just 30 mph.


Figure 1. Morning satellite image of Tropical Depression Bonnie. At the time, Bonnie had sustained winds of 30 mph.

Forecast for Bonnie
The current NHC forecast for Bonnie looks good, with the storm making landfall in Louisiana near 9pm CDT Saturday night. According to the latest tide information, this will be near the time of low tide. This will result in much less oil entering the Louisiana marshlands than occurred during Hurricane Alex in June. That storm brought a storm surge of 2 - 4 feet and sustained winds of 20 - 30 mph that lasted for several days, including several high tide cycles. Bonnie will be lucky to be a tropical depression at landfall, and should only create a storm surge of 1 - 2 feet that will come at low tide. This will result in a storm tide level that will inundate land to at most one foot above ground level.

Resources for the BP oil disaster
Map of oil spill location from the NOAA Satellite Services Division
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Elsewhere in the tropics
There are no other threat areas of concern today. The only model calling for possible tropical development in the next week is the NOGAPS model, which predicts a strong tropical disturbance could form off the coast of Nicaragua in the Southwest Caribbean about a week from now.

Next update
The next updates will be by wunderground meteorologists Rob Carver and Shaun Tanner. I'm taking advantage of a break in the tropical action to take a few days away. I'll be back blogging on Friday, at the latest.

Jeff Masters

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Quoting StormW:


Nice post Levi.

What I am mainly referring to is, mainly the effect of the NAO in regards to SAL and cooling of the SST's, in that even though you can go positive on the NAO for 2 maybe even 3 months, things can recover pretty quick.


Indeed. Although sometimes, such as in 1955, the trade wind flow is increased south of the A/B High but it is farther north, 20N or northward, where the strongest band of easterly anomalies are, and that can serve to cool the SSTs north of 20N. But then, that helps focus the heat in the MDR! Cooling the SSTs that far north actually aids tropical activity, so sometimes even stronger trade winds cooling SSTs can benefit a season if it takes place far enough to the north.

In fact, we've had a more neutral-positive NAO so far this month with faster trades (but further north than normal) and look at the cooler band of water between 25N and 30N. That is really quite beneficial to the eastern Atlantic.



Member Since: November 24, 2005 Posts: 635 Comments: 26547
Quoting SLU:
Positive NAO in August and September 2005. Look at the tracks. Apart from Katrina, Rita and the very short-lived and weak Jose, there was a lot of poleward moving tropical cyclones.




















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Quoting seflagamma:


Absolutely!


amazing isn't it.
Wilma is the 3rd most costly storm in American History behind Katrina and Andrew and everyone but us here in S Florida keeps forgetting about it...
Plus all those records it broke while developing in the Caribbean.

and no one ever talks about Wilma.


no one forgets Wilma, the point of the post was to show storms that formed in August and September of 2005, when the NAO was positive

Wilma formed in October, that is why it was not included
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The 30 Costliest U.S. Hurricanes


Rank: Name: Year: Category: Damage (U.S.)*:
1. Katrina (LA/MS/AL/SE FL) 2005 3 $81,000,000,000
2. Andrew (SE FL/SE LA) 1992 5 $34,954,825,000
3. Wilma (FL) 2005 3 $20,600,000,000
4. Ike (TX/LA/MS) 2008 2 $18,000,000,000
5. Charley (FL) 2004 4 $14,000,000,
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but me! :o)

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Quoting sammywammybamy:


YOU NEED PUT WILMA ON THERE. ASAP.!!!


Absolutely!


amazing isn't it.
Wilma is the 3rd most costly storm in American History behind Katrina and Andrew and everyone but us here in S Florida keeps forgetting about it...
Plus all those records it broke while developing in the Caribbean.

and no one ever talks about Wilma.
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420. sammywammybamy 6:32 PM GMT on July 24, 2010

read his post again, it was for tracks of storms in August and September of 2005, when the NAO was positive

Wilma formed in October
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The ECMWF itself forecasts for the Eastern Atlantic to be wet. One interesting thing to note is the subsidence in and around the Gulf of Guinea associated with cool SST anomalies. The net effect of cool Gulf of Guinea is that the precipitation rates increase north of the region of subsidence yeilding higher precipitation totals.

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Taking a look at the EUROPSIP forecast, you can see the Eastern Atlantic precipitation levels are forecasted to be around normal levels. All of the precipitation is focused in the Western Atlantic.


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418. SLU
Positive NAO in August and September 2005. Look at the tracks. Apart from Katrina, Rita and the very short-lived and weak Jose, there was a lot of poleward moving tropical cyclones.



















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417. unf97
Looking at WV and visible imagery the BOC disturbance on the coast of Mexico is looking more interesting. Looks as if an anticyclone is over the system. The system is stuck in weak steering currents. This has been the case for over 24 hours now as it has basically been stalled in this same region.. Convection keeps pulsating and you can see spinning right on the coastline.

Looks to continue to meander around but I anticipate it to eventually move a little farther inland though.
Member Since: September 25, 2007 Posts: 0 Comments: 1193
Check out 1955....had a highly positive NAO during July, August, and September, but look at where the MSLP anomalies ended up. The tripole pattern of a positive NAO can support low pressures in the tropics. Compare to this year:

1955 MSLP Anomalies July-August-September:



2010 MSLP Anomalies so far this July:




Now, 1955 had 12 named storms but this was before the satellite era so there were likely a couple more, and it was a very bad year in terms of ACE and landfalls. Of those 12 storms only 3 didn't make it to hurricane strength, and the US saw 5 landfalls, 2 of them major. North Carolina saw 3 landfalls. The Caribbean saw 2 major hurricanes make landfall and a 3rd one move through and make landfall as a Cat 2. This was one of those years were storm tracks were congregated west and south, with most of them affecting land. 1955 is tied at 2nd place with 2004 and 1995 for the most retired storm names in a single year (four).

It was a very bad year in reality, and the storm total was likely higher than 12. Conditions were very similar to this year except for the fact that we were not coming out of an El Nino and had been in La Nina conditions for a long time prior to the season. That is the only reason this was not one of my analog years. However, it is a very good example of the kind of bad seasons that can continue during cold PDO periods where La Nina dominates the Pacific for multiple years at a time. In other words, next year, 2011, will probably be bad as well, but not as bad as this year.

Member Since: November 24, 2005 Posts: 635 Comments: 26547
Quoting Tropicsweatherpr:
A question for StormW, Drakoen, Levi or 456. Does La Nina seasons tend to be less active than Neutral? I ask because Dr Masters has posted in past blogs a graphic that compares Neutral vs La Nina and by average, Neutral seasons have had more activity than La Nina ones.



Take out 2005 and you'll find that neutral years are just as active as La Nina years
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Well Henry's iz around da corner..and I multitask and use a phone a lot.

Presslord screams a lil,,but Im used to dat by now.



It is NOLA fer crying out loud..

..and thanks to wu-blogger NOLA2005 and her mate for stopping by during the Portlight Rummage and Art Sale here Uptown yesterday.

Nice folks fo sho

Oh,and You dropped something out yer pocket SC.

Ciao,,abiento
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Quoting stormlvr:


It has been a long time, but if I remember right, the fight weather maps for pilot briefings were developed with aerial coverage in mind.


Oh no.... I posted an A or B answer to keep from getting confused... Now everyone is making it an essay... LOL Ill just assume that Storm W knows and go wit it....

now Im just a ConfusedCaster....
Member Since: July 1, 2005 Posts: 10 Comments: 1683
Quoting Patrap:
going to Henry's 110 Anniversary Street Party.

Hopefully the Pig is done...at 2pm



Beats mowing grass..

Snicka,grin..Holla Back Boyz



Just HOW do you party so much, do charitable work, and still have time to blog on here with decent and accurate information?

I need to learn from you.
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Quoting unf97:


It means that there is a 60% probability in which rain will fall in that particular weather forecasting area. Probabilities are used in terms of how much of a particular region will see coverage in precipitation.


It has been a long time, but if I remember right, the flight weather maps for pilot briefings were developed with aerial coverage in mind.
Member Since: August 12, 2007 Posts: 0 Comments: 323
A question for StormW, Drakoen, Levi and 456. Does La Nina seasons tend to be less active than Neutral? I ask because Dr Masters has posted in past blogs a graphic that compares Neutral vs La Nina and by average, Neutral seasons have had more activity than La Nina ones.

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Quoting KEEPEROFTHEGATE:


2010 storm total map


That map is going to fill up fast starting about mid August...
Member Since: July 1, 2005 Posts: 10 Comments: 1683


2010 storm total map
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BOC is next I think :)



AOI

AOI

AOI

AOI

Landfall Points

TS BUSTED FORECAST ALIBI
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Quoting StormW:


Agreed Levi. I was just pointing out that some folks had made past posts about the NAO going positive, and because of it, that the season is a bust.

I'm working on something on my blog right now. Gonna drop da bomb on the downcasting.


=)
Member Since: November 24, 2005 Posts: 635 Comments: 26547
Quoting Patrap:

A Straight Dope Classic from Cecil's Storehouse of Human Knowledge
What does it mean when "X percent chance of rain" is predicted?
August 8, 1986

Dear Cecil:

When the weather service predicts some percentage chance of rain for the next day, what does this number mean? I always figured they compiled certain parameters about current conditions and compared them to analogous days in the past. The percentage of those days in which it rained is then used as the predicted chance of rain now. In other words, they base the percentages on historical data. However, a friend who is a pilot (and who presumably should know about these things) claims that the figure is determined by looking at the current conditions of a storm system which is expected to pass over us. The number represents the percentage of the area the storm is now passing over in which it is actually raining. This strikes me as complete bullshit.

Anyway, what's the straight dope on the predicted chance of rain? How can you ever have 100 percent chance of rain? How reliable are these figures?

— Ted F., Chicago

Cecil replies:

You are one shrewd hombre, Ted, no doubt as a result of having been exposed to this column regularly during your formative years. Your guess about what the percentages mean is pretty much on the money.

Here's what happens. The National Weather Service (and various other weather services around the world, under the guidance of the World Meteorological Organization, a UN agency) sends up measuring devices called radiosondes in helium balloons twice a day. These collect weather data continuously as they rise through the atmosphere--wind speed and direction, temperature, barometric pressure, and humidity. The information is radioed to the ground and eventually ends up at the National Meteorological Center near Washington, D.C., where it's fed into a computer. (There are other centers in other parts of the world that do the same thing.) Other data from satellites and ground reporting stations are also fed in, and what you end up with, metaphorically speaking, is a complete three-dimensional picture of atmospheric conditions around the world. The computer program then applies various laws of fluid mechanics to predict future conditions.

Unfortunately, there is only so far you can go with this. While it's possible to predict the temperature, say, with a reasonable degree of certainty, precipitation is much chancier. The best forecasters can do is to give the probabilities, which they do by having the computer compare present conditions with historical data. When you hear there's a 10 percent chance of rain, that means that out of the last 100 times the weather conditions were just like they are now, it rained 10 times. (More or less--I'm obliged to oversimplify a bit.)

The weather service has been calculating precipitation probabilities for as long as anybody can remember, but it's only been in the last decade or two that the nation's cadre of broadcast weather beings has deigned to convey this to the masses. Why the belated fascination with numbers I don't know; I suppose they feel it gives an aura of precision to a business that, let's face it, is still about one jump ahead of tea-leaf reading. But who can say?

As for your last couple of questions: a 100 percent chance of rain means that out of the last x number of times things were just like they are now, it rained every time. (It does not, incidentally, mean it's raining right this second.) On the question of how reliable the figures are, the amazing truth is that they are absolutely 100 percent reliable all the time--that is, presuming the raw data were fed in properly and the calculations done correctly. Remember, we're just talking about probabilities here. A probability isn't "wrong" if it tells you there's only a 10 percent chance of rain and it rains anyway; it's only wrong if a series of such predictions doesn't pan out over the long haul. Not much comfort if your dermis gets damp next time you're out on a picnic, but it'll have to do.

ANOTHER VIEW

In Washington, Oregon, and British Columbia, we have a different interpretation of precipitation forecasts. If the weatherman says there's a 20 percent chance of rain, that means it will rain 20 percent of the day. If there's a 50 percent chance, it will rain 50 percent of the time, etc., up to 100 percent, which means, of course, a typical January day. This interpretation seems to be quite accurate. --Joyce K., Seattle

— Cecil Adams


Thanks Pat.. Good read there...
Member Since: July 1, 2005 Posts: 10 Comments: 1683
399. unf97
Quoting IKE:
I guess it's hot out there by that oil-volcano and Bonnie decided to take what was left of her clothes, off.


LOL.. That was a pretty good line Ike.
Member Since: September 25, 2007 Posts: 0 Comments: 1193
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397. IKE
I guess it's hot out there by that oil-volcano and Bonnie decided to take what was left of her clothes, off.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting StormW:


Agreed Levi. I was just pointing out that some folks had made past posts about the NAO going positive, and because of it, that the season is a bust.

I'm working on something on my blog right now. Gonna drop da bomb on the downcasting.


Gotta love the tease line :)
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Quoting Patrap:
WUnder if we will get a invest out of the BOC..?




That would be interesting with the predominate flow around that large ULL in the NW GOM...
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Quoting Patrap:
There was a Bonnie?


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Quoting StormW:


Agreed Levi. I was just pointing out that some folks had made past posts about the NAO going positive, and because of it, that the season is a bust.

I'm working on something on my blog right now. Gonna drop da bomb on the downcasting.


hmmmm...that sounds interesting.
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Sun is trying to peek through in North Biloxi! :)
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Quoting unf97:
Patrap thanks for posting the explanation regarding the precipitation pprobabilities. Good read!


Anytime..

Twas a good read..

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Quoting StormW:


B.


That is what I thought it was but didn't say just in case I was wrong. I am not a met by no means....
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387. unf97
Patrap thanks for posting the explanation regarding the article on precipitation probabilities. Good read!
Member Since: September 25, 2007 Posts: 0 Comments: 1193
2005 had a positive NAO in August and September....surprise.
Member Since: November 24, 2005 Posts: 635 Comments: 26547
xx/xx/03L
MARK
28.2N/86.9W
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going to Henry's 110 Anniversary Street Party.

Hopefully the Pig is done...at 2pm



Beats mowing grass..

Snicka,grin..Holla Back Boyz

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Look, I turned the sprinklers off, where's the rain?

Link
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Quoting StormW:
More food for thought. Just went through, and picked out years since the upswing in activity beginning in 1995, and compared the NAO as far as negative and positive in JUL and AUG. Looking at the NAO forecast, it appears to go positive until the first week of Aug. Out of the years that come close, 6 years had a positive NAO in either Jul or Aug. The average storm total worked out to be 14. This did not include 2005.


Positive NAO can often be good for tropical activity and not bad during the summer. The numerical index isn't a clear-cut indicator of the pattern in the Atlantic during the summer months.
Member Since: November 24, 2005 Posts: 635 Comments: 26547

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About

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