Archive for August 31st, 2008|Daily archive page

Hanna Expected To Become A Hurricane

The forecast chart below was derived from WeatherUnderground and represents the 2 pm EDT forecast plot.  Currently tropical storm Hanna is expected to become a hurricane if it moves, as expected, over the warm waters of the Bahamas (fed by the warmth of the Florida Current and the Antilles Current).  The current between the Florida Peninsula and the Bahama platform is ofter referred to as the Gulf Stream but most physical oceanographers consider it to be the Florida Current.  It is implied that the Gulf Stream begins where the Florida Current merges with the Antilles Current.  Here is a link to Surface Currents In the Atlantic Ocean:

http://oceancurrents.rsmas.miami.edu/atlantic/florida.html

From the menu box near the top you can individually check out the Loop (mentioned in the previous posting), the Florida Current, the Antilles Current, and the Gulf Stream.

One of the most common misconceptions in physical oceanography is that the current off the eastern coast of Florida is the Gulf Stream.  If you are interested in common misconceptions in science that I have encountered through the years, here is a link to that topic (websites by Davis):

http://librarytech.org/learningzone/science1.html

If this does not come up, click on the link at the right margin of this web-log on the Common Misconceptions In Science notation.

PLEASE LEFT CLICK TO MAKE IMAGE LARGER
PLEASE LEFT CLICK TO MAKE IMAGE LARGER

GULF TEMPERATURES ARE VERY IMPORTANT NOW!

PLEASE LEFT CLICK ON IMAGES TO MAKE THEM LARGER ON YOUR SCREEN.

Sea surface temperatures can be important variables regarding the likelihood for strengthening or weakening of a tropical system.  Conditions aloft are generally more important.  A tendency toward divergence aloft is likely to increase the strength of a hurricane and a tendency toward convergence aloft is likely to decrease the strength of a hurricane.  Gustav appears to be one of those typical noteworthy storms being influenced significantly by the warm temperature (and higher evaporation rates) at the surface.  The chart below shows heat potential for yesterday (Saturday, August 30).  I added the labeling and I drew the current location (which is nothing more than a guess on my part).

Hurricanes are very unstable.  Vertical motion is imperative to the maintenance of the system.  Though tap water in a sauce pan is stable when you first put in on the stove top, heating it from below tends to make it unstable.  The extreme case of boiling (by heating from below) provides us an example of violent instability.  Clouds are the markers in our otherwise transparent air (I’m ignoring visible pollution here) and the cumuliform varieties show us some of the vertical action occurring – akin to a slow motion rendition of the water boiling in the saucepan.

Conversely, cooling the air (or cooling the water in the saucepan) from below tends toward stability.  No one, wanting to get water up to a boil would put the saucepan on top of a block of ice.

Let us all hope that when Gustav moves over the relatively cooler water that is becomes “less unstable” and weakens significantly.  THE PROBLEM FOR ME IS THIS:  The color coding in such charts is misleading for some because the blues leave one with the impression that the water is cold.  It is not “cold.”  The second chart in this posting gives you a clearer impression of the actual temperatures yesterday.

Hanna May Take A Turn 8-30-08, 11pm EDT Forecast

Left click the image for enlargement.

5-Day with cone of uncertainty

5-Day with cone of uncertainty

GUSTAV AT 11:45 PM EDT, 8-30-08

The image below is a color-enhanced satellite floater of Gustav after the eye completed its buzz saw trip over Western Cuba.  Heating from below coupled with high evaporation rates tend to intensity such storms.  The Gulf temperatures in the storm’s path are high.  It is my opinion that intensification will occur.

LEFT CLICK TO ENLARGE IMAGE

LEFT CLICK TO ENLARGE IMAGE