Featured Images

Hurricane Season 2009: Tropical Storm Enrique (Eastern Pacific)
08.10.09
 
August 10, 2009

Weakening Rainfall in Enrique Was a Harbinger of His Doom

TRMM satellite reveals a weakening Tropical Storm Enrique. > View larger image
NASA's rainfall data from the TRMM satellite revealed a weakening Tropical Storm Enrique, which hinted at his demise by August 10. Credit: NASA/SSAI, Hal Pierce
By Monday, August 10, what was once Tropical Storm Enrique had dissipated in the Eastern Pacific Ocean.

Looking back, August 7 was an indication of what was happening to Enrique. On August 7, both Hurricane Felicia and Tropical Storm Enrique had both weakened over the past 24 hours. Hurricane Felicia dropped from a dangerous category 4 hurricane on August 6 to a still powerful category 2 storm on August 7. Tropical storm Enrique continued to lose power and was down to tropical depression strength on August 7.

Hurricane Felicia's track was judged by the National Hurricane Center Miami, Florida to no longer be influenced by tropical depression Enrique and Felicia was predicted to further weaken and move toward the west-northwest. The rainfall analysis on the right was made using data captured when the Tropical Rainfall Measuring Mission (TRMM) satellite flew above the twin tropical cyclones on August 7, 2009 at 9:54 a.m. EDT (1354 UTC). Rainfall from TRMM's Microwave Imager (TMI) data was overlaid on an Infrared image from TRMM's Visible and Infrared Scanner (VIRS). The TRMM orbit is shown in shades of blue. A GOES-11 Infrared image from August 7, 2009 at 1400 UTC is shown as a black and white background.

Text credit: Hal Pierce, SSAI/Goddard Space Flight Center



August 7, 2009

NASA Satellite Reveals Enrique's Rainfall Fading Fast

TRMM image of Enrique > View larger image
TRMM captured this image of Enrique's weak rainfall on Aug. 6, 2009. Enrique isn't expected to last through the weekend.
Credit: NASA/SSAI, Hal Pierce
NASA's Tropical Rainfall Measuring Mission (TRMM) satellite has seen Tropical Depression Enrique's rainfall dwindling over the last day, and it appears that he'll weaken into a remnant low over the weekend.

TRMM captured the decreasing rainfall in Enrique in an image it captured while flying over the storm on Aug. 6 at 5:24 p.m. EDT. Since then, Enrique's rainfall has continued to wane in intensity.

Looking at TRMM data, forecasters at the National Hurricane Center noted in their discussion on Aug. 7 at 11 a.m. EDT, "Enrique maintained a small area of convection near its center during the night. However...the convection has very recently dissipated and the cyclone is close to being declared a remnant low. We will wait a little longer to make sure that organized deep convection does not redevelop."

By noontime EDT on Friday, Aug. 7, Enrique's maximum sustained winds were still near 35 mph, but the storm didn't have re-developing thunderstorms to keep it going. The depression was moving northwest near 9 mph, and had a minimum central pressure near 1007 millibars. By the end of the weekend, Enrique's last "curtain of rain" will likely fall.

Text credit: Rob Gutro, NASA's Goddard Space Flight Center



August 6, 2009

NASA Eyes Category 4 Hurricane Felicia and a Stubborn Enrique

Hurricane Felicia (left) and Tropical Storm Enrique (right) side-by-side on August 5 at 3 p.m. > View larger image
The MODIS instrument on NASA's Terra satellite captured Hurricane Felicia (left) and Tropical Storm Enrique (right) side-by-side on August 5 at 3 p.m. EDT.
Credit: NASA, MODIS Rapid Response
Notice Felicia's eye in the center of the storm; purple is colder than -63F and blue is -27F or colder. > View larger image
The AIRS instrument on NASA's Aqua satellite caught the icy cold clouds in Felicia (left) and Enrique (right). Notice Felicia's eye in the center of the storm. In this false-colored image, purple indicates temperatures colder than minus 63F and blue is minus 27F or colder.
Credit: NASA/JPL, Ed Olsen
Felicia is the storm that rules the Eastern Pacific Ocean this week, but Enrique refuses to give up. Felicia is a major hurricane with sustained winds near 140 mph, and Enrique is still hanging onto tropical storm status with 50 mph sustained winds. Both cyclones are close to each other and two NASA satellites captured them together.

On August 6 at 5 a.m. EDT, powerful Felicia is still a category four hurricane on the Saffir-Simpson hurricane scale. She's far out to sea, about 1,480 miles west-southwest of the southern tip of Baja California near 15.5 north and 131.2 west. She's moving west-northwest near 10 mph, and is expected to speed up and start to weaken in the next couple of days because of colder waters in her path. Felicia's minimum central pressure is 937 millibars.

Boys can be stubborn, and Enrique is proving that, even though he's a tropical storm with a boy's name. Despite Enrique's close proximity to Felicia, he's maintaining sustained winds near 50 mph. At 5 a.m. EDT, Enrique's center was 345 miles behind Felicia's, near 20.7 north and 125.9 west. He's speeding northwest near 17 mph into cooler waters which is going to weaken him over the next day or two. Enrique's minimum central pressure is 1,000 millibars, much higher than Felicia's indicating a much weaker storm. The higher the atmospheric pressure the weaker the tropical cyclone.

NASA's Terra satellite flew over Felicia and Enrique and using the Moderate Imaging Spectroradiometer (MODIS) instrument captured them side-by-side on August 5 at 3 p.m. EDT. The satellite image clearly showed an eye in powerful Hurricane Felicia, while Tropical Storm Enrique's eye was not clear.

Terra wasn't the only satellite to capture Felicia and Enrique battling it out for territory in the Eastern Pacific Ocean. NASA's Aqua satellite also flew overhead and its Atmospheric Infrared Sounder (AIRS) instrument captured the frigid cloud temperatures in both storms. Felicia's clouds are colder and higher than Enrique's clouds, because stronger hurricanes have higher (and more powerful) thunderstorms.

Using AIRS and other infrared imagery to determine cloud temperature, the National Hurricane Center noted in their discussion on August 6, that Felicia's "eye has been warming and has become more well-defined over the past few hours but at the same time the cold cloud tops around the eye have also been warming." That's an indication that Felicia will start waning in strength.

Text credit: Rob Gutro, NASA's Goddard Space Flight Center



August 5, 2009

NASA Satellite Sees Rainfall in Intensifying Hurricane Felicia and Tropical Storm Enrique

TRMM captured this image of Felicia's (left) and Enrique's (right) rainfall on August 4, 2009 9:28 a.m. EDT. > View larger image
TRMM captured this image of Felicia's (left) and Enrique's (right) rainfall on August 4, 2009 9:28 a.m. EDT. TRMM revealed a well defined center of circulation in Felicia indicating strengthening. She became a hurricane after this image was captured.
Credit: NASA/SSAI, Hal Pierce
NASA's Tropical Rainfall Measuring Mission captured a two-for-one satellite image of what is now Hurricane Felicia and Tropical Storm Enrique, which are in close proximity of each other in the open waters of the Eastern Pacific Ocean. TRMM, as the satellite is also called, captured the increasing rainfall in Felicia as she strengthened overnight into a hurricane. TRMM also captured the decreasing rainfall in Enrique overnight.

Felicia and Enrique recently formed fairly close to each other in the eastern Pacific Ocean southwest of Mexico. The TRMM satellite passed over the twin storms on August 4, 2009 at about (9:28 a.m. EDT) 1328 UTC. The TRMM satellite had a better view of tropical storm Enrique because it passed almost directly above. The TRMM rainfall analysis revealed that Felicia, at that time a tropical storm, had a well defined center of circulation which was a sign the storm could reach hurricane status later, and it did. TRMM is managed by both NASA and the Japanese Space Agency, JAXA.

Hal Pierce, a meteorologist on the TRMM mission said, "When two tropical cyclones like Felicia and Enrique form close to each other they may have an interaction known as the Fujiwhara effect wherein the cyclones begin to circle around each another in a cyclonic fashion and are drawn closer together. The two vortices can be attracted to each other, and eventually spiral into the center point and merge."

On Wednesday Aug. 5 at 5 a.m. EDT, Felicia's winds had increased to 105 mph, making her a Category Two hurricane on the Saffir-Simpson Scale. More strengthening is forecast, and Felicia is expected to become a Major Hurricane, Category Three status, later today.

Felicia was located about 1,265 miles west-southwest of the southern tip of Baja California near 13.4 north and 128.2 west and moving west-northwest near 12 mph. Minimum central pressure is 970 millibars.

Meanwhile, Enrique remains a tropical storm with sustained winds near 50 mph. Enrique is forecast to weaken as he begins to interact with Felicia. Enrique's center was located east of Felicia's near 16.8 north and 120.8 west, about 825 miles west-southwest of the southern tip of Baja California. Enrique is moving west-northwest near 15 mph and minimum central pressure is 1000 millibars.

Forecasters are watching Enrique and Felicia because the two may indeed become one.

Text credit: Hal Pierce/SSAI and Rob Gutro/NASA's Goddard Space Flight Center



August 4, 2009

Two New Eastern Pacific Storms Born: Enrique and Tropical Depression 8E

Tropical Depression 8e's (left) and Tropical Storm Enrique's (right) clouds in the early morning hours of August 4, 2009. > View larger image The GOES-11 satellite captured an infrared image of Tropical Depression 8e's (left) and Tropical Storm Enrique's (right) clouds in the early morning hours of August 4, 2009 in the Eastern Pacific Ocean.
Credit: NASA/NOAA GOES Project
The seventh and eighth tropical cyclones in the eastern Pacific Ocean formed late yesterday and are chasing each other in the open ocean.

One of them has already been named "Enrique" as it has strengthened into a tropical storm, while the other, located in front of it (to Enrique's west) was named "Tropical Depression 8E (TD8E)."

At 5 a.m. EDT on Aug. 4, Tropical Storm Enrique was located 725 miles south-southwest of the southern tip of Baja California, near latitude 14.0 north and longitude 115.7 west. Enrique was packing sustained winds near 40 mph and is expected to strengthen further. Enrique was moving west-northwest near 17 mph with a minimum central pressure of 1004 millibars.

At the same time, Tropical Depression Eight-E is speeding in front of Enrique, about 450 miles farther west. TD8E was located about 1,175 miles southwest of the southern tip of Baja California, near latitude 12.3 north and 123.9 west.

TD8E's sustained winds are currently 35 mph, but it is expected to strengthen into a tropical storm later today, August 4, and get the name Felicia. TD8E is moving west-northwest near 13 mph, not quite as fast as Enrique, but he is expected to slow down later today. TD8E's minimum central pressure is 1006 millibars.

GOES-11, the Geostationary Operational Environmental Satellite provided infrared imagery of both tropical cyclones' clouds at 5 a.m. EDT on August 4. It showed that both storms were becoming better organized.

GOES-11 is operated by the National Oceanic and Atmospheric Administration, and images are created by NASA's GOES Project, located at NASA's Goddard Space Flight Center, Greenbelt, Md.

Text credit: Rob Gutro, NASA's Goddard Space Flight Center