Archive for the ‘Cape Verde Storms’ Category

Bermuda Is Experiencing a Weakened Igor – 9-19-2010


Part of the image  above was done in 2007 and part in 2008.  I copied this from Google Earth this morning to give you an idea of the size and configuration of the beautiful British Overseas Territory of Bermuda.  Notice the 5 mile long scale at the lower left.  Latitude and longitude are also shown at the bottom margin.  This view is from an altitude of over 17 miles.  I recommend Google Earth for those of you who might be interested in more detail which is readily available.  There is a free version available.  With practice you can have great fun exploring the earth. The free version of Google Earth 5 is the one that appears first on the page.

Yesterday Hurricane Hunter aircraft crews found that the inner 23-mile wide eyewall had collapsed during what seemed like a fairly typical eyewall replacement cycle.  A very large 92-mile wide eye was the result and, and as usually happens in such events the hurricane weakened.  Currently hurricane force winds are now spread out over a larger area but Igor is “down” to a category 1 hurricane.  Much of the big eye wall has collapsed and though that is good news, Bermuda is still in for some strong winds of long duration – and intensification is still a possibility.  In any event, there is likely to be considerable damage to beaches and some structures.  I am under the impression that residents of Bermuda are “hurricane savvy” and probably better prepared than those who live along Eastern coastal U.S. A.

According to a 9-17-2010 posting on, “Homes in Bermuda are typically one or two stories and constructed of ‘Bermuda Stone,’ a locally quarried limestone, or of concrete blocks. Roofs are commonly made of limestone slate tiles cemented together. Commercial buildings, typically of reinforced concrete construction, rarely exceed six stories. In both residential and commercial buildings, window openings are generally small and window shutters are common. These features make Bermuda’s building stock quite resistant to winds, and homes are designed to withstand sustained winds of 110 mph and gusts of up to 150 mph.”





I’m posting this on the afternoon of Wednesday, 9-15-2010.  What you will be looking at as you view the animation above is, to my mind, fantastic.  I would have loved to have had such a tool to use in the college classroom when I was a full-time meteorology professor.  Even though this is jerky, it gives a wonderful view of things which I and my students could only imagine back before my retirement from the profession.  The stream will quickly get to mid-day (of Monday, Sept. 13) and the sun will quickly reach the western horizon marking sunset.  If you focus upon the eye in the afternoon you will see the shadow created by the wall cloud’s western margin as it creeps eastward.  Also watch the boiling cumuliform tops in various places.  I was fascinated by the way the clouds moved within the eye of the storm as it rotated.  ENJOY!

SPECIAL NOTE:  For those of you who understand hurricane circulation in more detail than most, notice the lower level clouds converging cyclonically (counterclockwise in the Northern Hemisphere) and look hard enough at the more diffuse high clouds and you will detect the anticyclonic divergence (clockwise in the Northern Hemisphere).  The latter is easiest to see on the west side of the storm where you can envision the feathered cirrus moving toward the north or northwest.  If they seem to you to be standing still that is because the ice crystals are sublimating at the leading edges of the clusters (turning from solid to gas) whereas deposition (gas to solid) is occurring at the trailing edges.

Watch the digital clock at the bottom margin of the image and you will note that after the initial spurt of one frame per 15 minutes, it settles down to a nicer one frame per minute.

*  *  *  *  *  *  *

This hurricane is a very strong one and potentially dangerous – particularly for the 65,000 or so people in Bermuda.  Let’s hope that they escape unharmed.  I’m hoping that Igor takes a surprisingly sharper right turn than anticipated in order to spare those fine people.

However, no matter the outcome, it’s difficult not to be in awe of this beautiful beast.  It’s also important, I think, to recognize that there are some good things about this storm especially when coupled with the impending effects of Julia which is positioned further to the east.  A certain amount of energy MUST be transformed over the Atlantic in order that it not be all released at once.  An analogy:  It’s better to have one tiny earthquake per year along an active fault than wait for 100 years before all of that stored energy is released as one gigantic earthquake.

The fact that Igor and Julia are both releasing huge amounts of latent heat into the atmosphere is good – particularly when that is happening over relatively uninhabited places.  Generally such long fetches over such long periods of time will move warm, tropical water such that it is replaced from below by cooler upwelling water.  That is good because the next system to move by is less likely to have as much oceanic heat to stoke it.

At the time I’m writing this (about 5 pm EDT, 9-15-2010) Igor is a category 4 hurricane and Julia is a category 3.  However, not many hours ago Julia was also a 4 and she might intensify to that category again.  According to my sources, this is only the second time in history that we have had two category 4 storms in the Atlantic at the same time.

Dr. Jeff Masters of wrote of that fact in his weblog today.  Rather than mimic what he has said, I’m placing his well-written statement below in blue.

Yours Truly,

T. Ansel Toney

e-mail =

“The Atlantic hurricane season of 2010 kicked into high gear this morning, with the landfall of Tropical Storm Karl in Mexico, and the simultaneous presence of two Category 4 hurricanes in the Atlantic, Igor and Julia. Tropical Storm Karl’s formation yesterday marked the fifth earliest date that an eleventh named storm of the season has formed. The only years more active this early in the season were 2005, 1995, 1936 and 1933. This morning’s unexpected intensification of Hurricane Julia into a Category 4 storm with 135 mph winds has set a new record–Julia is now the strongest hurricane on record so far east. When one considers that earlier this year, Hurricane Earl became the fourth strongest hurricane so far north, it appears that this year’s record SSTs have significantly expanded the area over which major hurricanes can exist over the Atlantic. This morning is just the second time in recorded history that two simultaneous Category 4 or stronger storms have occurred in the Atlantic. The only other occurrence was on 06 UTC September 16, 1926, when the Great Miami Hurricane and Hurricane Four were both Category 4 storms for a six-hour period. The were also two years, 1999 and 1958, when we missed having two simultaneous Category 4 hurricanes by six hours. Julia’s ascension to Category 4 status makes it the 4th Category 4 storm of the year. Only two other seasons have had as many as five Category 4 or stronger storms (2005 and 1999), so 2010 ranks in 3rd place in this statistic. This year is also the earliest a fourth Category 4 or stronger storm has formed (though the fourth Category 4 of 1999, Hurricane Gert, formed just 3 hours later on today’s date in 1999.) We’ve also had four Cat 4+ storms in just twenty days, which beats the previous record for shortest time span for four Cat 4+ storms to appear. The previous record was 1999, 24 days (thanks to Phil Klozbach of CSU for this stat.)”

Today’s Three Named Storms – Color Image – 9-14-2010

Cropping and yellow insertions by T. Ansel Toney. Left click twice for full enlargement.

Dear Tropical Weather Watchers,

I cropped the image above from a full disk image.  It was taken from the 4:45 pm (EDT) transmission of the GOES-13 weather satellite which is positioned at an altitude of 22,300 miles above the Equator at longitude 75 West.  At that altitude it orbits earth with the same period of revolution as the earth’s spin on its axis.  Therefore it stays over the same point (though it can be moved either east or west if desired).  By contrast, the International Space Station orbits at only 236 miles above the surface and the U.S. Shuttle crafts fly lower than that sometimes but have also gone higher – up to 365 miles or so above the surface to the Hubble Telescope.  It should be noted that neither the Space Station, the Shuttles, nor the Hubble are on equatorial orbits like the GOES Weather Satellites but instead they are at an inclination of 51.6 degrees to the equator.

In this image provided the sun had gone well past zenith and therefore you can see the bright eastern side of Igor’s eye wall.  It’s a very impressive storm.



More information about the three tropical weather systems depicted here can be found at the following site:

Click on each for printed reports.


Left clicks will enlarge.

Here is the 8 am EDT forecast track for Tropical Storm Igor.


Gaston has weakened to the point where it has lost its closed rotation.  This means it has returned to the status of tropical wave (synonymous with tropical disturbance).  However, some of the more dependable computer models expect it to regain strength soon.  My advice is to ignore the CLP5 track in the chart above; it is a baseline derived from recent directional tendencies and is used as a tool “after the fact” to evaluate the accuracy of the more analytical models.

You have probably noticed that I tend to focus on those storms which could be a threat to Florida and the Gulf Coast and once that threat passes I generally assume that you get plenty of continuous information from television news.  Though it is quite repetitive and there is some “drama” I still highly recommend the Weather Channel.  Here is a link to their Hurricane Central page:

We have friends in our West-Central Florida neighborhood, wonderful people, who are currently in Nova Scotia.  Therefore, since some of my concerned neighbors consult this site, I’m including this current statement about Earl’s expected effect upon Canada.  This comes verbatim from the WeatherUnderground website, appearing in Dr. Jeff Masters’ web-log (11:54 am EDT):

Impact of Earl on Canada

“Winds will begin to rise on the southwest coast of Nova Scotia late Friday night and early Saturday morning. By late morning Saturday, Earl is expected to make landfall somewhere between the Maine/New Brunswick border and central Nova Scotia. At that time, Earl will probably be a strong tropical storm with 55 – 60 mph winds. Earl will be moving at a very rapid 25 – 30 mph when it arrives in Canada, and regions on the right side of the eye can expect winds 15 – 20 mph greater than on the left side, due to the fast forward motion of the hurricane. Earl’s impact is likely to be less than 2008’s Hurricane Kyle, the last hurricane to hit Nova Scotia. Kyle hit near Yarmouth, Nova Scotia, as a Category 1 hurricane with 75 mph winds. Kyle produced a storm surge of 2.6 feet, and did $9 million in damage to Canada. The 11am EDT NHC wind probability forecast is calling for a 15% chance of hurricane-force winds in Yarmouth, and 3% in Halifax.”


Two independent left clicks will fully enlarge

Remember, tropical systems of this scale move generally from east to west if they have an entire ocean over which they can travel.  The reason for that tendency is multifaceted but it has to do more with the forces that dominate the general large-scale circulation of the atmosphere than anything else.  I will produce a posting with diagrams on that subject soon.

The lineup shown in the satellite image above is impressive to say the least though it is not unusual for this part of the Atlantic Hurricane Season.  Let’s hope that nothing serious comes of any of these systems.  However – I imagine that is wishful thinking.

Besides – everything is relative.  For example:  Since hurricane Andrew was relatively dry and part of the roof over the living room stayed on we were able to salvage some of our furniture.  The closest place I could find a truck to rent and storage was 100 miles north in Boynton Beach.  When my wife and I were up there we stopped at a Publix to purchase some provisions.  In the checkout lane we overheard a lady seriously complaining because her hair stylist was in Dade County and her standing weekly appointment had to be canceled because there was no electricity at the shop due to the hurricane.  Those of you who know me probably find it hard to believe that I kept my mouth shut – but I did.  In fact, I smiled over it as we moved on.  Our house had just been literally destroyed a few days earlier so this ladies concerns seemed a bit trivial to me.  However, for some reason – perhaps gratitude for being alive and having no one in my family injured – I felt that I needn’t bother to waste my time trying to convince her that her “problem” was not worth verbalizing in front of total strangers at a grocery store.  On the other hand, I’m sure some of my complaints seem trivial in the whole scheme of things.

AFRICAN LOWS 8-27-2010

For those of you who might be “old school” (like me) and enjoy surface pressure plots, I’m posting this current one that shows a line of lows over Northern Africa and Saudi Arabia – all of which are slowly migrating toward the west – which is typical for this time of year.  I’ve marked the cores of these lows in red. They are hot and dry but as soon as they move over the Atlantic they characteristically sweep up great amounts of moisture through evaporation.  Paradoxically, the addition of water vapor lowers the pressure and because of that the systems usually “deepen.”  Increasing winds make waves which increases the water surface for evaporation and whitecaps with bursting bubbles produces ejection filaments which break apart by gravity and cause even more surface to be available for evaporation.  During this phase of the hurricane season for some of these it’s “off to the races” as  tropical cyclonic systems evolve and track across the Atlantic.  Typically, the warmer the water, the higher the evaporation rates and the stronger the storms become.   NOTE:  Remember, the more water vapor in the air the less it weighs per unit volume – therefore the lower the pressure upon the surface. The opportunity for intensification is great because of the great length of ocean over which they can travel.  Once this happens – as long as they are over warm water about the only thing that can make them fade involves the air aloft (its temperature, velocity, and flow pattern).

Today’s Atlantic Color Image – 8-26-2010

Two independent left clicks will make this image very large.  It’s still hard for me to believe that we have access to such beautiful views.

Here is a very busy Atlantic in our hemisphere and come to think of it, the Gulf of Mexico is cluttered with lots of cloud cover.


Two independent left clicks will fully enlarge the image above.  For an even larger image see the link at the end of this post.

A new tropical wave (sometimes called tropical disturbances) has moved off Africa. From my point of view, they are now being shot off that continent toward the west in the manner of a repeating rifle. If this wave becomes a named storm it will be the third Cape Verde type in a row for this season.

Based upon the computer models for Danielle, I don’t believe that she will be a threat to the U.S. mainland.  However, even though the models are also showing an eventual sharp right turn for Earl – I’m uneasy about that.  As for this new wave – it’s too soon to tell.  When tropical cyclonic storms follow each other those not in the lead often are weakened by cooler water that wells up in the wake of the front-runner.  What happens is that the leader sweeps warm surface water away and it is replaced by cooler upwelling water from deeper down.  Let’s hope this happens with these trailing storms but there are certainly no guarantees.  Conversely, when a hurricane moves over warmer water, in most cases it tends to intensify.

I indicate below the cropped full disk image my opinion that it will become a named storm within the next 7 days. I emphasize the term, “opinion.” It is to be noted that I am not a trained forecaster. Professionally my special interest was cloud dynamics. The reason why I say that the name will probably be Fiona is because there is a remote chance that something could develop in the Gulf of Mexico prior to intensification of the new African wave and thus inherit that name.

I am in the habit of cropping the full disk image before posting because it depicts half of the earth and size-wise, eats up a lot of memory. But if you would like to enjoy the latest full discs here is a link: