Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather
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 ½ 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.
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