Author Archives: jay_hobgood

Tropical Storms Karina and Lowell and the Fujiwhara Effect

I am sometimes asked what happens when two tropical cyclones get close to each other.  The answer depends on the relative size and intensity of the two systems and how close they come to each other.  The Fujiwhara Effect is the name given to the tracks taken by the two vorticies.  If the two tropical cyclones are of nearly equal size and intensity, then they tend to move cyclonically around a center of rotation that is roughly half way between them.  If one cyclone is much bigger and stronger, then the center of rotation is shifted toward the bigger and stronger cyclone.

Tropical Storm Lowell has a large circulation and a maximum sustained wind speed of around 50 m.p.h.  Tropical Storm Karina is located about 700 miles to the west-southwest of Lowell.  Karina has a much smaller circulation and it also has a maximum sustained wind speed of 50 m.p.h.  Some of the models are forecasting that the two tropical storms will rotate around a point closer to Lowell than to Karina (i.e. the Fujiwara Effect).  This would result in Lowell moving general west-northwest and pass to the north of Karina.  The larger circulation of Lowell could also pull Karina back toward the east-northeast as Karina passes south of Lowell.  It is also possible that the circulation of Lowell could be so big that it captures Karina and Karina eventually gets absorbed by Lowell.

 

Three Tropical Waves

There are three notable tropical waves spread across the Atlantic and Caribbean this morning.  The first wave is over the eastern Caribbean Sea.  Thunderstorm activity has been gradually increasing with this wave and there may be an 850 mb vorticity center near latitude 12°N and longitude 62°W.  The wave extends northward to just east of Puerto Rico.  The wave is moving westward.  The models are not forecasting development of a tropical cyclone out of this wave at this time, but it may bear watching if the convection continues to increase.

A second tropical wave is located midway between Africa and the Lesser Antilles.  A low pressure system is located in the wave near latitude 12°N and longitude 36°W.  Cyclonic turning of the clouds is evident in satellite loops.  Drier air in the northern portion of the wave is limiting convective activity to the southern half of the cyclonic circulation.  Some runs of the GFS indicate modest development of the low pressure system as it moves westward.  In other GFS runs the low weakens before it reaches the Lesser Antilles.

A third tropical wave is located half way between Africa and the Cape Verde Islands.  A low pressure system is located in the wave near latitude 15°N and longitude 20°W.  Convection was impressive last night when the low first emerged from Africa and moved over the Atlantic.  However, strong easterly winds in the upper levels sheared the top off of this system and only a low level cyclonic circulation remains.   Earlier model runs indicated possible development of a tropical cyclone out of this wave, but more recent runs indicate that the upper level shear will continue and prevent development.

 

The Atlantic remains quiet

Tropical waves continue to move off Africa and weaken over the Atlantic Ocean.  A tropical wave about a thousand miles east of the Lesser Antilles continues to move westward with little convection.  Earlier in the week some models runs were suggesting that the wave might form into a tropical cyclone, but the models are no longer indicating that development will occur.

Julio becomes a hurricane again

An eye developed in Julio and it has been upgraded to hurricane status.  Even though Julio is located 600 miles north of Hawaii, it is over Sea Surface Temperatures (SSTs) that are warm enough to support a hurricane.  The upper level winds around Julio are light enough to allow for Julio to maintain a warm core.  Eventually, wind shear should increase and cooler SSTs will likely weaken Julio back to a tropical storm.

A new tropical depression has formed west of Mexico.  Tropical Depression Eleven-E (TD11E) is about 385 miles west-southwest of Manzanillo, Mexico and about 400 miles south of the southern tip of Baja, California.  it is moving toward the west-northwest at 16 m.p.h.  It is expected to intensify and if it becomes a tropical storm its name will be Karina.  Some numerical models are showing that it could eventually move in the general direction of Hawaii.

Welcome to my blog

Welcome to my personal blog and web site.  I hope you find things of interest to you in these pages.  Over the years people have asked me if I had a blog.  Up to now I resisted the urge to write one because it seemed to me that there were lots of other people writing about things and I didn’t want to become another person adding to the plethora of information available online.  It also takes time to generate content and I didn’t want to start a blog that withered quickly because I didn’t have time to keep it current.  However, people continue to ask me about the weather and so I finally decided to take the plunge.

I became interested in hurricanes after my family moved to Northwest Florida when I was growing up.  I started tracking hurricanes and tropical storms and I read everything I could find on them.  My interest continued when I went to college, although I had no idea at the time how to turn my interest into a career.  Even though I know a lot more about hurricanes now, I am still fascinated by them and continue to try to learn more about them.  I have done research on hurricanes over both the Atlantic and Eastern North Pacific and I still track every tropical cyclone in both of those basins.  Other aspects of weather and climate captured my interest over the years, and you may find things about other topics in this blog as well.

My goal for this blog is to provide information that may be useful and to help people who are interested in learning more about the weather do so.  I am not attempting to replicate or replace other sources of weather information.  Although I may talk about weather watches and warnings in this blog, readers should remember that national weather entities, such as the National Weather Service in the U.S, are the organizations that issue official weather statements.  There are also many media and other outlets that provide that information to the public.

I also hope to develop a more complete web site that will help people to understand aspects of the weather better.  I have spent much of my adult life teaching students about the weather and answering questions about it.  I intend to take what I have learned over the years and to try to put together a site that I hope will let people learn more about the weather features that interest them.  I enjoy explaining things and helping others learn.  Having said all of that, readers may need to have patience at times.  I do have a full time job and there are periods when it fully consumes all of my available time.  During those periods I may not post any new content.

I enjoy interacting with people interested in the weather and constructive suggestions are always appreciated.  However, if you are interested in starting an argument or if you have a political or other agenda, I respectfully ask that you move along to other sites that are in greater agreement with your views.  I dislike arguing with people and I am not interested in trying to change anyone else’s mind.  I set up this blog so that I have to approve any comments before they are posted.  I understand that some people may view this as a form of censorship, which it is, but I feel responsible for what is posted on this site and I want to keep it appropriate for all readers including any children who may find it.  As I activate more of the site, I will set up a link so you can contact me if you have suggestions or questions that you don’t feel comfortable posting in a more public forum.

Finally, I feel obligated to offer the standard sort of disclaimer about the content of this blog and web site.  The content is solely a reflection of my views and opinions.  It should not be construed in any way to reflect the opinions and policies of my employer, The Ohio State University, nor those of the people who host it.

Once again, welcome, and I promise future posts will be about hurricanes and the weather.