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 5th 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 just south of the Texas border as a Category 3 storm.

Emily became a tropical depression (TD #5) in the early morning hours of the 11th of July 2005 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 12th. The Tropical Rainfall Measuring Mission (TRMM) satellite has been following the progress of Emily. TRMM was launched back in November of 1997 to measure rainfall over the global Tropics and has proven itself to be a valuable platform for observing tropical cyclones. This first image was taken at 16:44 UTC (12:44 pm EDT) on 13 July 2005 as Emily was approaching the windward islands. 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 13th and entered the southeastern Caribbean as a Category 1 storm. Emily then intensified into a major hurricane becoming a Category 3 storm on the 14th and a minimal Category 4 storm on the Saffir-Simpson scale on the morning of the 15th of July 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 the 15th, 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 the 16th of July, 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. The next image from TRMM was taken at 01:20 UTC 17 July (9:20 pm 16 July EDT) and shows Emily southwest of Jamaica as a Category 4 storm. 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 the 17th of July, 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 the 18th of July, 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). However, conditions were favorable for restrengthening, and Emily began to re-intensify over the western Gulf of Mexico. TRMM captured this next image of Emily at 17:36 UTC (12:36 pm CDT) on the 19th in the western Gulf of Mexico as Emily was in the process of re-strengthening. 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. The final image was taken less than 7 hours later at 00:09 UTC 20 July (7:09 pm CDT 19 July) as Emily was nearing the northeast coast of Mexico. By this time, Emily's winds were back up to 110 knots (127 mph) according to NHC making it a Category 3 hurricane. 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.

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TRMM is a joint mission between NASA and the Japan Aerospace Exploration Agency (JAXA).

Images produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang (SSAI/NASA GSFC).