Archive for the ‘hurricane evacuation’ Tag

HURRICANE SEASON – IT’S NOT OVER!

We have been enjoying a few days of tropical inactivity after a “whirlwind” bout with some storms.  The news about Ike has tapered down greatly but lest we forget, there are many, many people suffering over that storm.  By the time Ike lost its hurricane status we had gone for 29 straight days with at least one named storm – Fay, Gustav, Hanna, and Ike.

By the end of next week there will probably be at least one named storm out there again.  Experts have been keeping an eye on the Madden/Julian Oscillation (MJO) which is an observed oscillation of tropical convection that is not well understood.  Interpretations are that within 3 to 6 days conditions will again be “ripe” for the development of tropical disturbances that have the potential to develop further – some eventually into named storms.  Understanding the graphical representations of the Madden-Julian Oscillation is not easy but I’m providing a link for those of you who are inclined to dig in deep or those who are simply curious about it.  If you are a meteorologist or a physicist (or just curious), I recommend you click on the “expert discussions.”

I’LL END THIS POST ON A HAPPY NOTE:

I received an e-mail today from the daughter of the owner of the “lone house standing” in Gilchrist.  I have asked her permission to put her comments in the main body of this web-log and will do so if she agrees.  I know that so many of you have been concerned.  The occupants evacuated and are A.O.K.  I will attempt to learn the extent of the damage but I doubt that they know at this time.  I don’t expect that they have been able to return to assess the damage.  I am very relieved to know that they didn’t try to ride out that storm even though they surely would have survived if they had stayed inside.  Now – let’s all hope that none of their neighbors got swept away with their homes.  In my opinion, if there are no fatalities among the Gilchrist residents, it will be a miracle.  It may very well be that all of them, knowing the hurricane history of that peninsula, decided to get out of there.  The location of her comment is at the end of my September 16 post titled Location of Gilchrist, Texas House – Some Clues.

LOCATION OF GILCHRIST, TEXAS HOUSE – SOME CLUES.

Finally, I learned from another sharp reader that the gentleman who first guided me to the location of the house was correct when he said that the house was a few blocks east of Rollover.  I interpreted that to be Rollover Street when in fact, Rollover is also the name of the bridge.  That is just too logical for me to have caught on.  LOL

Please visit the rest of this web-log at https://cloudman23.wordpress.com/.  If you are interested in weather, there are some tutorials scattered about and more will be added in time.

THE FORCE OF WIND – A GREAT SURPRISE FOR MOST PEOPLE

Moving along under a light breeze - working upwind with sails sheeted in close.

Please left-click this image for enlargement.

In order to changes gears for a moment, I’ve inserted a photo of a form of travel, recreation, and sport that utilizes the wind.  The image above is of my little sloop, Nature’s Way.  It was taken by my wife from a position onshore.  The craft has a fixed shoal draft keel that accounts for one-third of the weight (displacement) of the craft (1,100 pounds).  In spite of the keel, she is very easy to launch from the trailer and also easy to retrieve – pretty much a one-person job.  I wish for everyone that they could experience such peace as is provided by sailing in fair weather.  However, experienced sailors know that when the wind picks up, the force from it increases exponentially.  If they don’t know that fact and the wind velocity increases more quickly than they anticipate they are likely to some day find themselves in a position where they have waited too long to reduce the sail area.  Then they will have their hands full – especially if sailing solo.

This image shows the craft moving 45° “off the wind.”  In other words, under skillful hands the boat is being “pulled” as well as pushed by the wind in a general upwind direction.  Most sailboats with this type of rig can sail 45° off the wind but no closer than that.  However, by zig-zagging from one tack point to the other, the boat can reach an upwind objective.  It reminds me of working upslope on a mountain trail by taking a switchback route, rather than climbing directly upward.  SO, DON’T THINK THAT SAILBOATS ONLY SAIL IN THE GENERAL DIRECTION OF THE WIND – THEY CAN ALSO SAIL IN A GENERAL UPWIND DIRECTION AS IS BEING DONE IN THIS IMAGE (though there is about a 90° degree arc – 45° degrees on either side of the wind-line that they can’t sail effectively).  To be thorough I must add that some extremely well-designed boats with well-cut sails can get closer to the wind with a skillful skipper.

A sailboat can also sail nicely broadside to the wind.  That position is called a beam reach.  In time, for those of you who are interested, I will probably post a little tutorial on the points of sailing.  For now, I hope the image below with some elaborations will whet your appetite.  To reach it you must click the enticement to read on when you reach it at the end of the next paragraph.  Now – LET’S DISCUSS THE POWER OF A STORM’S WIND OR ANY OTHER WIND ACCORDING TO ITS VELOCITY:

There are some widespread misconceptions about the relationship between the wind’s velocity and the force it is able to exert.  Doubling the wind velocity quadruples the air’s potential force upon a surface that it strikes at right angles.  Early on in my teaching career it because quite apparent to me that most people assume that doubling the velocity simply doubles the force.  But that is far from true.  For example, a 110 mph wind has 4 times the potential force of a 55 mph wind! Continue reading

The Effect of Hurricane Winds Upon a House

Image courtesy of NOAA

Image courtesy of NOAA

What follows is an excerpt from a 1998 publication titled AMERICA’S HURRICANE THREAT under the auspices of the South Carolina Sea Grant Consortium.  What I’m showing you is a small part of their sobering account of what can happen to houses in the strong winds of a hurricane.  The house on the left in the image above is mildly damaged compared to many in that neighborhood.  I have been reading the above-mentioned report tonight due to my special interest in Hurricane Andrew.  Those of you who have been following this web-log since its beginning 18 days ago might recall having read somewhere that our home was a total loss in that 1992 hurricane.  In time, I have written about the experience in a recent posting dealing with window protection.  Here is the excerpt from the report:

“Andrew totally destroyed 63,000 homes and partly damaged another 110,000, making 250,000 people homeless. With roofs damaged or blown off, rain following the hurricane poured inside structures, soaking and collapsing Sheetrock and destroying billions of dollars worth of furniture, carpeting, televisions, and other items. The insurance industry estimates that 25-40% of insured losses were due to slipshod construction practices.

Most homeowners do not give a second thought to their roofs-until they leak or disappear. Yet roofs are the Achilles heel of homes in hurricane-prone areas from Maine to Texas.

As strong winds strike a building, their flow is diverted, swirling over and around the structure. Think of a mountain stream roaring against a giant boulder, which deflects the current. The stream flow accelerates around the obstacle, resulting in rapids. In the same way, hurricane winds speed up around corners and edges, creating suction that pulls on building materials like a super-powerful vacuum hose. Fierce gusts and suction pressure make a dangerous combination, especially for roofs. They yank off tiles and shingles, first at the roof edge and then along its slope as you’d peel an orange. During Andrew, huge numbers of tiles were stripped from roofs this way, and carried off by high winds, they crashed through windows by tens of thousands.

If you lose a window or door during a hurricane, you’re in big trouble. Extreme winds push through an opening in a building, increasing air pressure inside like blowing up a balloon beyond its capacity. If you force enough air pressure inside a house, it can break at its weakest point, usually the roof.

As roofs are being pushed off from within, they are being pried loose from the outside. Peel away tiles or shingles and you’ll find a covering of roofing paper, under which is plywood attached to rafters. But a roof won’t stand much of a chance in hurricane-force winds if builders haphazardly tie down plywood to rafters-if they use too few nails or miss the rafters altogether with their nail ‘guns.’ After Andrew, engineers reported that many contractors had routinely missed their marks. ‘With the use of automatic nail guns, the workman lost his feel for the nailing process,’ said Saffir. ‘The result was that many nails went through the sheathing into thin air, not into the truss or rafter below. This was a common occurrence.’

If your plywood sheeting flies away in the wind, you’ve lost more than just a roof covering. You’ve also lost a portion of the house’s structural integrity. That is, plywood sheets are often the sole lateral bracing for the rafters, actually holding the roof together. So with the plywood gone, the rafters are loosely tethered in the wind.

To compound the problem, many contractors fail to tightly fasten wood gable ends-the flat ends of a pitched roof-to walls. So when a powerful gust hits an unbraced gable, the gable end can be pulled loose at the wall, allowing wind to enter the building. If the roof sheathing is pulled off at the gable end, the rafters can fall over.

During hurricane Andrew, tens of thousands of homes were damaged due to such failures in roofs.”

NOTE FROM CLOUDMAN23:  Many of you reading this could be living in dwellings without adequate roof truss tie-downs and/or with poor roof sheathing attachment.  Do you know what the codes were when your house was built?  Do you feel confident that your dwelling was built according to code?  Were the inspections thorough and particular or were they inadequate?  For some, those are hard questions to answer.  In any event, please evacuate if Ike is heading your way.  Heed the warnings.  Please.

Please visit the rest of this web-log at https://cloudman23.wordpress.com/.  If you are interested in weather, there are some tutorials scattered about and more will be added in time.  At the end of this page there is a cue to click to the previous page or the next page.