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Hurricane Season 2007: Lorenzo (Atlantic)
09.26.07
 
Lorenzo Became a Hurricane, Hit Mexico and Weakened

Tropical storm Lorenzo increased in strength and was upgraded to a category one hurricane with wind speeds of 70 knots ( 80.5 mph) a few hours before it came ashore 40 about miles south-southeast of Tuxpan, Mexico.

TRMM image of Hurricane Lorenzo on Sept. 28, 2007


Lorenzo weakened after it came ashore but is still expected to produce torrential rainfall as it moves slowly inland. The image above was made from the Tropical Rainfall Measuring Mission (TRMM) satellite data captured on Sept. 28, 2007 at 0327 UTC (11:27 p.m. EDT, Sept. 27). It shows very heavy rainfall of over 50 mm/hr (2 inches per hour) falling in the eyewall of the hurricane as it was coming ashore in Mexico. Rain rates in the center of the satellite swath are based on the TRMM Precipitation Radar (PR), and those in the outer swath on the TRMM Microwave Imager (TMI). The rain rates are overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS).

By 11:00 a.m. EDT on Friday, Sept. 28, Lorenzo moved further inland in Mexico, and weakened to a tropical depression. His center was located at that time near 20.6 degrees north latitude and 98.4 degrees west longitude, or about 70 miles west-southwest of Tuxpan, Mexico. Lorenzo was moving west near 9 mph and should continue on this track for another day or two until he dissipates. Lorenzo's maximum sustained winds decreased to near 35 mph, and his minimum central pressure was 1002 millibars.

Lorenzo is expected to produce total rainfall accumulations of 5 to 10 inches with possible isolated maximum amounts of 15 inches over portions of east-central Mexico. These rains could cause life-threatening flash floods and mud slides.

Lorenzo is expected to dissipate by Sunday, Sept. 30. Credit: Hal Pierce and Rob Gutro, Goddard Space Flight Center



Tropical Depression 13 Expected to be Named Lorenzo

Satellite image of Tropical Depression 13
Click image for enlargement.

On Thursday, Sept. 27, 2007, the National Hurricane Center was keeping a close eye on Tropical Depression 13 (TD#13) as it remains almost stationary off the eastern coast of Mexico. TD#13 is expected to strengthen to a tropical storm and would then receive the name Lorenzo.

At 11 a.m. EDT, TD#13's center was located near 20.7 north latitude and 95.2 west longitude and isn't moving. That puts TD#13's center about 200 miles east-southeast of Tampico, Mexico and about 145 miles east of Tuxpan, Mexico. TD#13's estimated minimum central pressure was 1008 millibars and it had maximum sustained winds of 30 knots with gusts to 40 knots.

Taking action, the government of Mexico issued a tropical storm warning for the Gulf coast of Mexico from Palma Sola to Cabo Rojo. A tropical storm warning means that tropical storm conditions are expected within the warning area within the next 24 hours. A tropical storm watch remains in effect from north of Cabo Rojo to la Cruz.

Tropical depression thirteen is expected to produce total rainfall accumulations of 5 to 10 inches over the Mexican state of Veracruz with possible isolated maximum amounts of 15 inches.

This infrared satellite image from Sept. 27 at 8:23 UTC (4:23 a.m. EDT) was created by data from the Atmospheric Infrared Sounder (AIRS) on NASA's Aqua satellite. This AIRS image shows the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures (in purple) are associated with high, cold cloud tops associated with the lingering showers and thunderstorms. The infrared signal does not penetrate through clouds. Where there are no clouds the AIRS instrument reads the infrared signal from the surface of the Earth, revealing warmer temperatures (red). This infrared image shows the leading edge of the strongest convection (rising air and heavier rain) from TD#13 in purple now just onshore, while the remainder lingers over the Gulf of Campeche.

Rob Gutro (From NHC reports)
Goddard Space Flight Center
Image credit: NASA/JPL




Thirteenth Tropical Depression Forms in Bay of Campeche, Off the East Coast of Mexico

Satellite image of Tropical Depression 13
Click image for enlargement.

Mexico has been the target of several hurricanes or tropical cyclones this season, and the thirteenth tropical depression joins the crowd.

Tropical Depression #13 (TD#13) formed in the Atlantic Ocean hurricane season formed today, Sept. 26, 2007 near the east central coast of Mexico, in the Gulf of Mexico.

The National Hurricane Center reported at 11:00 a.m. EDT that TD#13 is very close to tropical storm strength. Maximum sustained winds are near 35 mph (55 km/hr) with higher gusts. Some strengthening is forecast during the next 24 hours and the depression could become a tropical storm later today. If that happens, Tropical Storm Lorenzo would be born.

An air force hurricane hunter aircraft is scheduled to investigate the system this afternoon. Tropical storm watches may be required for a part of the Gulf Coast of Mexico today.

At 11:00 a.m. EDT on Sept. 26, TD#13's center was located near 20.9 degrees north latitude and 95.0 degrees west longitude. That's about 205 miles or 335 kilometers east-southeast of Tampico, Mexico and 155 miles or 250 kilometers east of Tuxpan, Mexico. TD#13's estimated minimum central pressure is 1006 millibars.

Why is TD#13 is Meandering Off the Mexican Coast?

TD#13 is basically meandering off the coast, drifting southward near 2 mph (4 km/hr) and its movement is forecast to continue to be slow and erratic. That's because the winds ("Steering winds") that would steer the tropical depression are weak. Hurricanes are "steered" by the prevailing wind currents that surround the storm from the surface to 50,000 feet or more. The storms move in the direction of these currents and with their average speed. The movement of a hurricane affects the speed of the winds that circulate about the center. The winds around TD#13 are currently weak, so the storm won't move too quickly.

This infrared satellite image from September 26 at 7:41 UTC (3:41 a.m. EDT) was created by data from the Atmospheric Infrared Sounder (AIRS) on NASA's Aqua satellite. This AIRS image shows the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures (in purple) are associated with high, cold cloud tops associated with the lingering showers and thunderstorms. The infrared signal does not penetrate through clouds. Where there are no clouds the AIRS instrument reads the infrared signal from the surface of the Earth, revealing warmer temperatures (red). This infrared image shows the strongest convection (rising air and heavier rain) from TD#13 in purple off the coast of Mexico in the Bay of Campeche.

Image of Tropical Depression 13
Click image for enlargement.

The top image is a visible satellite image from the National Oceanic and Atmospheric Administration's Geostationary Operational Environmental Satellite (GOES-12). The image, from Sept. 25, was supplied through the U.S. Naval Research Laboratory.

The image on the bottom is from NASA's CloudSat satellite. The red line through the GOES satellite image shows the vertical cross section of radar, basically what TD#13's clouds look like sideways. The colors indicate the intensity of the reflected radar energy. The top of Ingrid's clouds reach almost to 14 kilometers, or approximately 8.7 miles high. The blue areas along the top of the clouds indicates cloud ice, while the wavy blue lines on the bottom center of the image indicate intense rainfall.

Rob Gutro (From NHC reports)
Goddard Space Flight Center
Images credit: NASA/JPL; NASA/JPL/Colorado State University/Naval Research Laboratory-Monterey