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Katrina's 2nd anniversary, and the tropical update

By: Dr. Jeff Masters , 02:31 PM GMT die 29o August, anno 2007

A tropical wave midway between Africa and the Lesser Antilles (94L) has changed little since yesterday. QuikSCAT data from 4:47am EDT this morning shows a poorly organized system with a weak, elongated circulation. Top winds were 25 knots (29 mph). Visible satellite loops show a limited amount of disorganized thunderstorm activity. Wind shear is a favorable 5-10 knots over 94L, and should not be a problem for it until Friday or Saturday. By then, 94L will be moving through the Lesser Antilles Islands, and may encounter high wind shear if it is far enough north to feel the winds of an upper-level low pressure system that will be just north of Puerto Rico.

The presence of a large, dusty area of dry air surrounding its north side is the main thing holding back 94L. This dry air is being sucked into the circulation and is interfering with the storm's organization. When the dry air encounters a thunderstorm inside 94L, this denser dry air gets incorporated into the thunderstorm's downdraft, accelerating the downdraft, and creating arc-shaped surface cumulus clouds that mark the downdraft's position as it spreads out along the ocean surface (Figure 1). The presence of these arc-shaped surface clouds is usually a good sign that a storm is struggling with dry air and will not intensify significantly for at least the next 12 hours.

Water vapor satellite loops of the region show that 94L has not significantly moistened its environment. As the storm continues further west, it should be able to gradually do so, allowing it more of a chance to get organized. The system should track through the Lesser Antilles Islands on Friday, which is the earliest day I expect it could become a tropical depression. None of the reliable computer models make a believable forecast showing 94L developing into a tropical depression before it reaches the Lesser Antilles. The GFDL develops 94L into a tropical storm once it makes it into the central Caribbean south of the Domincan Republic, and this is a believable forecast, if 94L hangs together and makes it into the central Caribbean. The Hurricane Hunters are on call to investigate 94L on Friday.

Figure 1. Visible satellite image of 94L, show arc-shaped outflow boundaries from thunderstorm downdrafts.

South Carolina low
An area of low pressure has developed a few hundred miles off the South Carolina coast, along an old frontal boundary. This disturbance has been designated "95L" by NHC this morning. QuikSCAT showed a sharp wind shift but no closed circulation around 95L this morning at 6:34am EDT, and measured winds as high as 50 mph. Wind shear is about 15 knots over the disturbance, which is drifting south into a region where wind shear is expected to remain low enough to allow some development this week. I do think 95L will become a tropical depression, and most of the computer models also agree on this. The models disagree substantially on 95L's track, though. Steering currents will be weak in its vicinity, and 95L may spend a number of days wandering erratically. The Hurricane Hunters will investigate 95L Thursday afternoon.

Coast of Africa
The UKMET model is indicating the possible development of a tropical depression by Friday off the coast of Africa. There is a large surge of moisture with at least one strong tropical wave embedded in it coming off the coast of Africa this week, and it would be no surprise to see this wave develop into a tropical depression.

Katrina, two years later
Two years ago today, on August 29, 2005, Hurricane Katrina smashed into the Gulf coast with Category 3 winds and an incredible storm surge up to 27.8 feet high. Wunderblogger Mike Theiss was at ground zero in Gulfport, Mississippi during Katrina, and has posted a blog this morning on his experience, complete with some very compelling photos. His video of the storm surge washing into the hotel he was at is the most amazing storm video I've ever seen.

Margie Kieper's Katrina's Storm Surge feature on our tropical page provides an extraordinarily detailed 16-part examination of each portion of the coast devastated by Katrina. Margie is scheduled to be a guest on the Talking Tropics Internet radio show Thursday night to talk about Katrina's storm surge. Check the listings to see if there are any last minute changes.

The photo above was taken from Part 8: Lakeshore to Waveland, MS of Katrina's storm surge. An excerpt from the text:
I found an astonishing photo, of the peak of the surge in Waveland, which didn't appear to be faked, but I'm pretty much of a skeptic. The photo had this caption, "Photo taken in Waveland, MS, just North of the Railroad Tracks during Katrina around 9 AM by Judith Bradford." Note that it is being taken from the second floor window of a home, and that the water is close to the roof line of the first floor. There is a man perched on what is left of a home across the street, wearing a tiny life jacket and clutching a neon green pool noodle. There are electric lines running down from a pole to a home from left to right. In the distance on the right is a home with water up to the roof line. It is likely after 9am, as the bulk of the surge came between 9 and 10 am (that is when most of the fatalities occurred along the Mississippi coast), and probably the eye is already overhead, as the water is relatively calm and there appears to be little wind or rain, even though the pine trees are bent from the recent force of the eyewall winds.

The information provided by the Bradfords regarding the surge was very specific. The power went out at around 6:30am at their Waveland home on the morning of the 29th. They were staying in the home for a couple of reasons; first, because the home had not received any water at all from Camille, and, secondly, because both work in the medical field and needed to be available after the storm. At almost exactly 8:30am, water started coming over the railroad track embankment, from the coast, and into their yard.

Their home is 18 inches off the ground, and the first floor has 8-foot ceilings. There is an 18-inch truss between the 1st and 2nd floors, and this is what saved their 2nd floor from being flooded. In a matter of only five to ten minutes the water came up six feet, and quickly filled the first floor after that. Judith said that is why they saved so little from the first floor; they had no time to get anything. She first tried to shut the living room front door, but the force of the water burst the door open. She grabbed a camera and the Bradfords and their children ran upstairs. They marked the high water mark (HWM) on the inner stairwell showing how high the water came ? a little more than six more inches into the truss, which is a total of 10 feet of surge.

They saved two other people besides the man who was floating by on the roof in the photo. He was a chef named Glen, holding a four month old dachshund named Pinky, in the surge. He had lost his other dog and three cockatiels when his mother's home collapsed. The roof wedged against their van, underwater, and stopped, so they were able to save him. Bill Bradford told me when he swam out to rescue that man, that the water was so warm it seemed almost hot. He said the current was nothing like white water, but was a gentle continuous flow.

Because their home is right by the railroad tracks, it is not as high in elevation as I had thought. It is around 17 feet elevation. That is close to the HWM observed in Pass Christian, 27 feet.

With such a good quality HWM, I wondered why their house was not surveyed. Judith Bradford told me that no one from the federal government seemed to realize their house was there. The road leading up to Jeff Davis (they own 6 acres and raise miniature horses, which were drowned in their stables when the surge came) was filled with debris. The teams doing Search and Recovery for bodies didn't even check the house because they didn't know it was there; it was a good thing the family survived!

The water started to go down sometime after 11am, and by noon was about chest high, and by 2pm about waist-deep. The water finally left the house completely by about 4 or 5 pm that evening. She believes the railroad track embankment kept the water from receding faster. "

I'll have an update Thursday morning, unless there's a major change in 94L or 95L. My thoughts and prayers are with all those affected by Hurricane Katrina today. Let us not forget what happened two years ago.

Jeff Masters

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54. Texascoaster
3:25 PM GMT on August 29, 2007


Funny, but all week they have been saying "moving west over land don't worry about it".
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53. gsueagle07
3:20 PM GMT on August 29, 2007
There you go...the Dr has said what I have been saying all along....too much dry air...very poorly organized...this one is history......have a great weekend!
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52. MTJax
3:21 PM GMT on August 29, 2007
The HPC shows 95L lingering till Friday and then another LOW replaces it through day 6.

Day 3 Fronts
Click to view latest Day 3 fronts forecast
Day 4 Fronts
Click to view latest Day 4 fronts forecast
Day 5 Fronts
Click to view latest Day 5 fronts forecast
Day 6 Fronts
Click to view latest Day 6 fronts forecast

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51. stormchsngrl
3:13 PM GMT on August 29, 2007
Thank You Dr Masters', excellent explanation once again. Thank you to all of you posting comments. I really enjoy reading the information each day.

Thank you for the Katrina information also.

Eyes to the Sky !!
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50. srada
3:19 PM GMT on August 29, 2007
So is the GFS or GFDL not picking up on 95l?
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49. BrandonC
3:18 PM GMT on August 29, 2007
OK I guess I stand corrected as we will have 4 possible storms to watch by Friday. . . Hurricane Center is talking about the storm over the Yucatan moving into the bay of campeche as something to watch as well . . .
48. Crawls
3:17 PM GMT on August 29, 2007
Anyone got any comments on the possible development that the UKM shows here?

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47. putintang3
3:09 PM GMT on August 29, 2007
Well I will not put to much worry in 95L, just as long as it don't do any flip flops out there.
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46. stormybil
3:08 PM GMT on August 29, 2007
as for 95l it could develope more as it moves south it depends on how far south it goes before the front pickes it up and moves it ne . but a nother player might push it west its a tough call for 95l just a wait and see witch front wins
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45. Bigguy675
3:08 PM GMT on August 29, 2007
Thanks for the info StormW and Emagirl
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43. rwdobson
3:08 PM GMT on August 29, 2007
El Nino/La Nina is part of an oscillating cycle of ocean temperatures. Often refered to as ENSO (El Nino-Southern Oscillation). El Nino results in less Atlantic activity, and warmer winters in the US. The "slow" season of 2006 and the warmth of early winter 06-07 was due to El Nino. It has now oscillated back towards La Nina.
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42. TerraNova
11:08 AM EDT on August 29, 2007
Here's another large shot of the models for 95L.

I currently think this may take an Andrea-like track; not coming too close to Florida, meandering off shore for a few days, then swinging off the northeast.
Member Since: July 30, 2007 Posts: 76 Comments: 4063
41. BrandonC
3:05 PM GMT on August 29, 2007
Good morning guys it sure is good to be back in touch with a computer. Been gone for a long while since Dean was still going. I see that we have 2 invests to play with and possibly a third by Friday if the African wave follows the Ukmet guidance.
40. hurricane23
11:07 AM EDT on August 29, 2007
Here's another large shot of the models for 95L.
Member Since: May 14, 2006 Posts: 8 Comments: 13857
39. nash28
3:06 PM GMT on August 29, 2007
SHIPS is always on the high side.

I usually don't put too much in it until the system deepens into a storm.
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38. stormybil
3:05 PM GMT on August 29, 2007
does anyone have a link to the ship models thanks
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37. putintang3
3:04 PM GMT on August 29, 2007
The dry air does seem to be getting pushed away
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36. TerraNova
11:06 AM EDT on August 29, 2007
Hello Storm,

I have a question and I hope you don't mind me asking, but yesterday you said that an anticyclone would develop at the 200 millibar level over 94L; is this it?

Member Since: July 30, 2007 Posts: 76 Comments: 4063
35. floridagrrl
3:03 PM GMT on August 29, 2007
Morning, StormW! Thanks for the great info yesterday! My kid and I spent the evening - and into this morning at her insistence - reading and learning. Yaawn, she cost me my beauty sleep. We're watching the African wave together. We may never have to read another boring science book....
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34. emagirl
3:03 PM GMT on August 29, 2007
el nina makes more active season
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33. Bobbyweather
11:04 AM EDT on August 29, 2007
SHIPS model brings 94L to hurricane strength in 3 days.
Member Since: September 7, 2006 Posts: 91 Comments: 2738
31. moonlightcowboy
2:52 PM GMT on August 29, 2007
Here's the current view of water vapor at the mid levels from the cimss. While 94L is getting some dry/dusty air entrainment, as it continues its track westwards it should find better development conditions. It's also more likely to make a wnw turn as it slowly strenghtens, and in the present, looks as if it may follow Dean's track.

That nw'erly track will depend on how far south the trough north of the system drops south. Being further south it may influence the storm's track to be more north of west. But, I don't think that'll happen maybe, until it reaches the Antilles. It's not as strong as Dean, and not likely to enter the eCarib as strong as Dean either. So, much will depend on how fast it strengthens and how it's influenced by the trough, or the high that is forecast to build back in. It's all timing right now. Faster and stronger = more northerly. Slower and weaker = more westwards.

Another look at dry, stable air. But, you can see the area wnw of 94L that is clearing the way for more favorable development conditions.

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30. hurricane23
10:59 EDT le 29 aot 2007
The wave of the african coast is fairly large and has alot moisture to work in the coming days.

It may also try to steal some energy from 94L but we'll se.
Member Since: May 14, 2006 Posts: 8 Comments: 13857
29. CJ5
2:48 PM GMT on August 29, 2007
94L has some decent outflow and spin. It needs some help in the moisture department and it needs to convection to wrap on the southern side. Its not terribe looking but needs a lot of help. I have not noticed any models that develop this past the E Carr. The Gfdl does carry it further and along a Dean track.

There is a good break in the High in 18-72 hour period which could bring it N. Though most models have it on a similar track as Dean. I think this invest, if it develops, would have a greater chance at NW movement than Dean did. The intensity seems suspect though.

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28. Bigguy675
2:54 PM GMT on August 29, 2007
El Nina and El Nino......would one of you guys say which is favorable for having less than an active hurricane season. The names are so similar that I always get them confused. I know number crunching real well but some of this meteorology stuff gets me confused....thanks
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27. Bobbyweather
11:00 AM EDT on August 29, 2007
SHIPS model brings 94L to TS strength in the next 24 hours.
Member Since: September 7, 2006 Posts: 91 Comments: 2738
25. nash28
2:57 PM GMT on August 29, 2007
Morning StormW!

I am off the rest of the week. Good thing so now I have ample time to watch the tropics:-)
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24. srada
2:54 PM GMT on August 29, 2007
Good Morning everyone,

I was asking yesterday about the potential development off the SC/NC coast and the steering patterns and basically everyone was saying this will get kick out to sea but It looks like what I said too, that is just a matter of timing on those fronts. the more I am on here, the more I learn, I appreciate everyone helping yesterday though.
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23. Bobbyweather
10:56 AM EDT on August 29, 2007
We might have Tropical Storm Gil sooner or later.
Member Since: September 7, 2006 Posts: 91 Comments: 2738
21. floridagrrl
2:51 PM GMT on August 29, 2007
Thanks, Dr. Masters. My 13 year old is officially a weather nut now, and your explanations and those of the bloggers here are so educational. Great job!!

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20. rwdobson
2:51 PM GMT on August 29, 2007
Good update Doc. Good to see some specific info that can help people interpret satellite images. Funny that the frontal low off the Carolinas has higher winds than this blob in the CATL.
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19. fsumet
10:52 AM EDT on August 29, 2007
MTJax, 50 is not the Africa wave, that is always there
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18. Crisis57
2:49 PM GMT on August 29, 2007
Posted By: hurricane23 at 2:44 PM GMT on August 29, 2007.

Coast of Africa
The UKMET model is indicating the possible development of a tropical depression by Friday off the coast of Africa. There is a large surge of moisture with at least one strong tropical wave embedded in it coming off the coast of Africa this week, and it would be no surprise to see this wave develop into a tropical depression.

Could get interesting with this wave.

what does the steering current look like for this wave H23?
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17. nash28
2:51 PM GMT on August 29, 2007
Agreed StormW. La Nina is for all intents and purposes here.
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16. Bobbyweather
10:48 AM EDT on August 29, 2007
we have TD 10E
Member Since: September 7, 2006 Posts: 91 Comments: 2738
13. hurricane23
10:43 EDT le 29 aot 2007
Coast of Africa
The UKMET model is indicating the possible development of a tropical depression by Friday off the coast of Africa. There is a large surge of moisture with at least one strong tropical wave embedded in it coming off the coast of Africa this week, and it would be no surprise to see this wave develop into a tropical depression.

Could get interesting with this wave.
Member Since: May 14, 2006 Posts: 8 Comments: 13857
12. weathermanwannabe
8:38 AM CST on August 29, 2007
Good Day All...Will be lurking today but agreed on the long term consequences of a "later" winter.....Will basically delay the regular Fall cooling of the tropical waters so the so called "peak" of the season may be extended a little more...But like all of this GW stuff, only long-term trends (20-30 years?)will be able to verify this type of issue...One early winter a few years down the road and the some of the "trends" start to go out the window....
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11. MTJax
2:41 PM GMT on August 29, 2007
Link to the models for all these storms. 94, 95, and 50 which is the Africa wave

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9. hurricane23
10:37 EDT le 29 aot 2007
We stay NEUTRAL for most of this season according to BOM with the possibility of weak NINA appearing later in the year.

Summary: La Nia indicators strengthen

Since late July there has been a gradual strengthening of most La Nia indicators. For example, surface temperatures in the eastern equatorial Pacific have approached or just passed La Nia thresholds and there has been further cooling below the surface. Trade Winds have been mostly close to or stronger than normal and cloudiness has been less than average over much of the tropical Pacific.

However, further strong cooling of the equatorial Pacific Ocean looks unlikely, as computer model guidance suggests ocean temperatures will remain near the La Nia thresholds until the end of the year. In the past, most significant La Nia events were firmly established by winter's end.

Furthermore, the SOI remains neutral at +2 for the past 30 days, a modest rise from the −4 for the month of July. Continued above average air pressure over Australia has contributed to both the neutral SOI and the below-normal rainfall over much of the country since the start of July. For 2007 to be confirmed as a La Nia year (late-developing by historical standards), the SOI needs to rise to around +7 or higher for several months while the present patterns of Pacific Ocean temperatures, Trade Winds and cloud patterns are maintained.

Complete update Here
Member Since: May 14, 2006 Posts: 8 Comments: 13857
2:39 PM GMT on August 29, 2007
Thanks for the information and the story. Katrina's wounds are still fresh for so many people. Let's just pray we have another safe year.
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7. weatherboyfsu
2:37 PM GMT on August 29, 2007
You took the words right out of my mouth......Anytime you see the arc clouds the system is not doing good.......The old John Hope use to talk about that back in the day......Still, 94L looks like it has alot going for it to become our next depression.........time will tell.....
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6. littlefish
2:35 PM GMT on August 29, 2007
Thanks Dr M, brief but great detail about the effects of dry air in struggling systems...
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5. bswigg
2:37 PM GMT on August 29, 2007
Thanks DR. M
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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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