WunderBlog Archive » Category 6™

Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.

Midget Marco makes landfall

By: Dr. Jeff Masters, 1:36 PM GMT on October 07, 2008

Tropical Storm Marco is making landfall along the Mexican Gulf of Mexico coast northwest of Veracruz. We really don't know how strong this storm is, because these so-called "midget" tropical cyclones are very difficult to classify correctly via satellite estimates. The only way to get an accurate idea of the strength of Marco is to fly a Hurricane Hunter airplane into the storm, and there has been only one flight into Marco (yesterday afternoon's flight). No further missions are planned.

Figure 1. Comparison of the sizes of Hurricane Ike and Tropical Storm Marco. Ike image was taken on September 11, 2008 (image credit: NASA. The Marco image was taken at 5 pm EDT October 6.

Midget tropical cyclones are rare in the Atlantic, but are fairly common the Western Pacific, where the presence of the monsoon trough often acts to spin up tiny tropical cyclones. Although small in stature, midget tropical cyclones are capable of intensifying into powerful hurricanes capable of causing severe damage. Tropical Cyclone Tracy, which hit Darwin, Australia on Christmas Day in 1974, was a midget tropical cyclone as small as Marco, but packed Category 4 winds. The storm killed 71 people and caused over $5 billion in damage.

Data yesterday afternoon from the Hurricane Hunters suggested that Marco's eye was just 3 miles across. Tropical storm force winds extended outward only ten miles from the center. Tropical storms this small are subject to sudden and unpredictable changes in intensity, and it wouldn't surprise me to see Marco with winds anywhere between 40 mph and 80 mph at landfall. The region affected will be just 10-20 miles across, and we don't need to worry about any significant storm surge with this storm! According to the latest analysis by NOAA's Hurricane Research Division, the Integrated Kinetic Energy (IKE) for Marco is as low as you'll see for a tropical storm: zero. They rate Marco's potential surge damage as a 0.3 on a scale of 1 to 6. For comparison, Ike and Katrina rated a 5.1 shortly before they made landfall. Comparing Marco to Ike (Figure 1), we can see that Ike was a Texas-sized storm that filled the entire Gulf of Mexico. Ike's tropical storm-force winds extended out up to 275 miles from the center at landfall. Marco is a Rhode Island-sized storm. At Marco's peak size, tropical storm-force winds covered an area of about 1,158 nm, which is 1/75 as big as Ike's.

Figure 2. Current satellite image Marco.

Elsewhere in the tropics
A small circulation near 11N, 37W, midway between Africa and the Lesser Antilles Islands, is kicking up some isolated heavy thunderstorms. The region is under about 20-30 knots of wind shear. The GFS and UKMET models continue to predict that a tropical depression could spin up in this region by Friday, and wind shear is predicted to drop to a level that might allow that to happen.

We will also need to watch the Western Caribbean for possible development late this week.

Hurricane Ike relief efforts
Here's today's update on the Hurricane Ike relief effort started by wunderground members Patrap, Presslord, and Stormjunkie:

The push to continue to keep supplies rolling to the Gulf Coast continues. This morning we shipped out three sets of packages with medical supplies and some cleaning supplies. The first set of two boxes went to the Bridge City Fire Department. It contained burn kits, bandages, first aid kits, Neosoprin, an air splint and more. The second set of boxes went to Eagle Heights Fellowship in Baytown. This is a shelter being run by a local pastor and seems to be one of the few shelters in this area that will remain open for the next four to six weeks. The supplies in these three boxes included CPR kits, first aid kits, disinfectant wipes, gloves, and more. The third set of three boxes were shipped to EmmyRose which she will personally deliver to the San Leon/Baycliff area. They included many of the same items listed above. We have estimated the value of these seven boxes to be between $4000 and $5000 which we shipped for just under $350.

Figure 3. More relief supplies on the way!

Contributions to this highly worthy portlight.org charity fund are fully tax-deductible, and will go to provide relief supplies for those smaller communities typically bypassed by the traditional relief efforts. More details can be found at StormJunkie's blog.

Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.