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Hurricane Emily Makes Landfall in Mexico, Twice
07.21.05
 
With the arrival of Hurricane Emily, the second major hurricane in the month of July, the 2005 hurricane season has gotten off to an unbelievably fast start. Already the record fifth named storm of the season by mid-July, Emily made landfall in Mexico as a major hurricane two separate times: first in the Yucatan Peninsula as a Category 4 storm and now again in Tamaulipas along the northeast coast south of the Texas border as a Category 3 storm.

Three dimensional image of Hurricane Emily provided by TRMM.


Image above: This image shows Hurricane Emily in three dimensions as captured by the TRMM satellite. Click on the image will allow the animation of Hurricane Emily to play. + Click here for a Quicktime version of the animation.

Emily became a tropical depression (TD #5) in the early morning hours of the July 11 in the central Atlantic well east of the Lesser Antilles and west of the Cape Verde Islands. Storms that form in this region are known as Cape Verde storms and typically do not form here until later in the season. However, water temperatures are warmer in the Atlantic this year. Emily continued to move westward towards the windwards islands and became a tropical storm 24 hours later on the morning of July 12.

The Tropical Rainfall Measuring Mission (TRMM) satellite has been following the progress of Emily. TRMM was launched in November 1997 to measure rainfall over the global tropics and has proven to be a valuable platform for observing tropical cyclones.

Hurricane Emily as seen by TRMM on July 13, 2005.


This first image (above) was taken at 16:44 UTC (12:44 pm EDT) on July 13 as Emily was approaching the windward islands. Click on image to enlarge. The image displays the horizontal distribution of rain intensity obtained within Emily as obtained from TRMM's sensors. Rain rates in the center part of the swath are from the TRMM Precipitation Radar (PR), the only radar capable of measuring precipitation from space. The PR can provide fine resolution rainfall data and details on the vertical structure. Rain rates in the outer swath are from the TRMM Microwave Imager (TMI). The rain rates are overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS). The image shows Emily as a tropical storm with maximum sustained winds reported near 60 mph by the National Hurricane Center (NHC). In this image Emily does not yet have an eye, although an area of intense rain (red area) is present near the center of the storm. The center of Emily is near the edge of the PR swath in this image.

While passing through the windward islands, Emily strengthened into a hurricane during the night of July 13 and entered the outheastern Caribbean as a Category 1 storm. Emily then intensified into a major hurricane becoming a Category 3 storm on July 14 and a minimal Category 4 storm on the Saffir-Simpson scale on the morning of July 15 with maximum sustained winds reported at 115 knots (132 mph) by the National Hurricane Center. Emily was now in the south-central Caribbean north of Venezuela and was moving west-northwest. During the afternoon and evening of July 15, Emily underwent some fluctuations in intensity as the storm underwent an eyewall replacement cycle and encountered wind shear from an upper-level low while crossing through the central Caribbean south of Hispaniola. On July 16, Emily once again strengthened into a Category 4 hurricane as it neared Jamaica with maximum sustained winds up to 135 knots (155 mph). In Jamaica, four people were washed away in their vehicle by heavy rain from the storm.

Hurricane Emily as seen by TRMM on July 17, 2005.


The next image from TRMM (above) was taken at 01:20 UTC July 17 (9:20 pm July 16 EDT) and shows Emily southwest of Jamaica as a Category 4 storm. Click on image to enlarge. A band of intense rain (red areas) is visible over Jamaica associated with an outer rainband northeast of the center. The center of Emily falls within the TMI swath in this image and is visible as the green (indicating moderate intensity rain) circular area. On July 17, Emily continued to churn through the western Caribbean, maintaining Category 4 intensity as it headed for the Yucatan Peninsula. In the early morning hours of July 18, Emily made landfall just south of Cozumel, Mexico as a Category 4 storm. Fortunately, there were no fatalities reported. As it passed over the Yucatan Peninsula, Emily's circulation was disrupted as is common when hurricane's pass over land. The storm emerged back over open water into the Gulf of Mexico on the 18th as a minimal Category 1 hurricane with maximum sustained winds down to 65 knots (75 mph).

Hurricane Emily as seen by TRMM on July 19, 2005.


However, conditions were favorable for restrengthening, and Emily began to re-intensify over the western Gulf of Mexico. TRMM captured the next image of Emily (above) at 17:36 UTC (12:36 pm CDT) on July 19 in the western Gulf of Mexico as Emily was in the process of re-strengthening. Click on image to enlarge. A well-defined eye is clearly visible with intense rain all throughout the northern half of the eye-wall (red semicircle). The surrounding rainbands are tightly curved (green circular features) with areas of embedded heavy rain (red areas). At this time, Emily was a strong Category 1 hurricane with sustained winds reported at 95 mph by NHC. The intense rain visible in the center of Emily in this image is a good indication the storm will continue to strengthen. As water vapor condenses into the cloud droplets that produce rain, heat is released. This heat, known as latent heat, is what drives the storm's circulation. It is most effective when it is released near the core of the storm as is the case here with Emily.

Hurricane Emily as seen by TRMM on July 20, 2005.


The final image (above) was taken less than 7 hours later at 00:09 UTC July 20 (7:09 pm CDT July 19) as Emily was nearing the northeast coast of Mexico. Click on image to enlarge. By this time, Emily's winds were back up to 110 knots (127 mph) making it a Category 3 hurricane, according to NHC. This image from TRMM reveals that Emily is in the process of forming a double eyewall (seen as the concentric green circles with areas of red embedded) and later verified by hurricane hunter aircraft and coastal radar. This type of pattern occurs in mature, intense hurricanes wherein an outer eyewall forms outside of the inner eyewall and eventually contracts and replaces the inner eyewall. This is just another indication that Emily was becoming more organized and more intense. However, Emily was already too close to land to become much stronger and finally came ashore on the northeast coast of Mexico about 75 miles south of Brownsville, Texas, as a Category 3 storm.

TRMM is a joint mission between NASA and the Japanese space agency JAXA.

 
 
Steve Lang
Goddard Space Flight Center