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Rachel (Eastern Pacific)
September 30, 2014

[image-96]Tropical Storm Rachel Dwarfed by Developing System 90E

Tropical Storm Rachel is spinning down west of Mexico's Baja California, and another tropical low pressure area developing off the coast of southwestern Mexico dwarfs the tropical storm. NOAA's GOES-West satellite showed the size difference between the two tropical low pressure areas.

NOAA's GOES-West satellite captured an image of the Eastern Pacific Ocean on Sept. 30 at 1200 UTC (8 a.m. EDT). In the infrared image, Tropical Storm Rachel appeared small in comparison to the low pressure area called System 90E, coming together hundreds of miles south. As Rachel spins down over cool waters west of Baja California, Mexico, southwesterly wind shear was obvious in the GOES-West image because the bulk of Rachel's clouds had been pushed to the north. The image was created by NASA/NOAA's GOES Project at the NASA Goddard Space Flight Center in Greenbelt, Maryland.

The National Hurricane Center (NHC) noted that Rachel was still maintaining tropical storm strength on Sept. 30 at 5 a.m. EDT, when maximum sustained winds were near 40 mph (65 kph). Rachel was centered near 23.3 north latitude and 117.5 west longitude, about 485 miles (780 km) west of the southern tip of Baja California. Rachel was stationary at the time.

NHC forecasters expect that southwesterly wind shear affecting Rachel to become even stronger, more than 30 knots, within a day or so. That means that the storm will weaken and the forecast calls for Rachel to degenerate into a remnant low by Wednesday, Oct. 1.

As Rachel weakens, an elongated area of low pressure called System 90E continues to consolidate a few hundred miles south of Acapulco, Mexico. The NHC noted that environmental conditions are favorable for a tropical depression to form later this week while the system moves toward the west-northwest or northwest near 10 mph.

Because System 90E is so close to the coast, it is expected to produce locally heavy rains over portions of southern Mexico that could cause flash flooding and mud slides.

Over the next two days, System 90E has a 50 percent chance of becoming a tropical depression and that chance skyrockets to 90 percent by day five.

Rob Gutro
NASA's Goddard Space Flight Center


[image-80]NASA's Aqua Satellite Sees Rachel Before Losing Hurricane Status

Tropical Storm Rachel strengthened into a hurricane over the weekend of Sept. 27 and 28, only to weaken back into a tropical storm by Sept. 29. NASA's Aqua satellite passed over Rachel before it weakened and took a visible picture of the storm off Baja California's coast.

Rachel became the Eastern Pacific Ocean's twelfth hurricane on Saturday, Sept. 27 at 5 p.m. EDT when maximum sustained winds reached 75 mph (120 kph). When NASA's Aqua satellite saw Rachel, the maximum sustained winds were at the same strength. At that time, Rachel's center was 485 miles (780 km) west of the southern tip of Baja California. The Moderate Resolution Imaging Spectroradiometer or MODIS instrument grabbed a visible image of Rachel as Aqua passed overhead showing bands of thunderstorms circling a cloud-filled eye. The image also showed that the band of thunderstorms in the storm's southeastern quadrant was less full than the bands circling the rest of the storm. 

By Sept. 29, strong upper-level south-southwesterly winds helped weaken Rachel and the tropical storm's cloud pattern appeared considerably less organized now than when NASA's Aqua satellite passed overhead.

At 11 a.m. EDT (1500 UTC) Rachel's maximum sustained winds were near 60 mph (95 kph) and steady weakening is expected over the next two days as the storm moves into cooler waters and battles vertical wind shear. The center of Tropical Storm Rachel was located near latitude 22.8 north and longitude 117.5 west.  That's about 485 miles (780 km) west of the southern tip of Baja California, Mexico. Rachel was moving toward the north near 2 mph (4 kph) the National Hurricane Center (NHC) expects it to become almost stationary before drifting southwestward by Tuesday, Sept. 40.

Rachel is forecast to become a remnant low on Tuesday, Sept. 29.

Rob Gutro
NASA's Goddard Space Flight Center


[image-51]Sept. 26, 2014  - NASA Identifies Cold Cloud Tops in Tropical Storm Rachel

NASA's Aqua satellite saw the area of strong thunderstorms with colder cloud tops had grown within the Eastern Pacific Ocean's Tropical Storm Rachel.

NASA's Aqua satellite passed over the large Tropical Storm Rachel on Sept. 25 at 4:41 p.m. EDT and the Atmospheric Infrared Sounder or AIRS instrument, saw that the extent of colder cloud tops had increased, indicating thunderstorm heights were increasing and it was strengthening. The expansion of those stronger thunderstorms also suggests that the northeasterly wind shear may be relaxing a little. The strongest thunderstorms remain limited to the southwest of the low-level center, 

At 5 a.m. EDT on Sept. 26, the center of Tropical Storm Rachel was located near latitude 18.0 north and longitude 112.9 west.  That's about 390 miles (630 km) south-southwest of the southern tip of Baja California, Mexico. Rachel is expected to go through a short period of strengthening before weakening again. Maximum sustained winds remain near 50 mph (85 kph).  Some strengthening is forecast through Saturday, Sept. 27, with weakening expected to begin by Saturday night.

Rachel was moving toward the west-northwest near 14 mph (22 kph) and is expected to turn to the north-northwest late on Sept. 27.

The National Hurricane Center forecast calls for an increase in wind shear by Sept. 28  and beyond while Rachel moves over marginally cooler water and into a drier, more stable environment. So, steady weakening is expected to begin by on Sunday, Sept. 28, with the cyclone likely becoming a remnant low early next week.

Rob Gutro
NASA's Goddard Space Flight Center


[image-36]Sept. 25, 2014 - Satellite Catches an Oval-Shaped Tropical Storm Rachel 

NOAA's GOES-West satellite spotted the eighteenth tropical depression of the Eastern Pacific grow into a tropical storm that was renamed Rachel today, Sept. 25, 2014. Wind shear is affecting the tropical storm, however, so it doesn't have a rounded appearance on satellite imagery.

Tropical Depression 18-E formed on Wednesday, Sept. 24 around 11 a.m. EDT about 285 miles (460 km) south-southwest of Manzanillo, Mexico.  Manzanillo is a city in the Manzanillo municipality of the Mexican state of Colima on the country's west coast.

In an infrared image from NOAA's GOES-West satellite on Sept. 25 at 1200 UTC (8 a.m. EDT), Tropical Storm Rachel appeared oval shaped, indicating wind shear was affecting the circulation. The image was created by NASA/NOAA's GOES Project at the NASA Goddard Space Flight Center in Greenbelt, Maryland. 

The National Hurricane Center (NHC) noted that microwave data showed Rachel's center was located to the northeast of the deep convection (thunderstorms) due to strong upper-level northeasterly winds.

At 5 a.m. EDT on Thursday, Sept. 25, Rachel's maximum sustained winds were near 40 mph (65 kph) and NHC forecasters expect slight strengthening over the next day or two. Rachel's center was located near latitude 16.0 north and longitude 108.6 west. Rachel was moving toward the west-northwest near 13 mph (20 mph) and that general motion is expected to continue during the next 48 hours.

According to NHC forecasters, Rachel is expected to strengthen a little over the next couple of days before weakening to a depression in four days.

Rob Gutro
NASA's Goddard Space Flight Center

GOES image of Rachel
In an infrared image from NOAA's GOES-West satellite on Sept. 25 at 1200 UTC (8 a.m. EDT), Tropical Storm Rachel appeared oval shaped.
Image Credit: 
NASA/NOAA GOES Project
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AIRS image of Rachel
NASA's Aqua satellite passed over the large Tropical Storm Rachel on Sept. 25 at 4:41 p.m. EDT and saw colder cloud tops (purple) indicating thunderstorm heights were increasing and it was strengthening.
Image Credit: 
NASA JPL, Ed Olsen
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NASA's Aqua satellite saw Rachel when it was briefly a hurricane off Baja California on Sept. 28 at 5:15 pm. EDT.
Image Credit: 
NASA Goddard MODIS Rapid Response Team
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GOES Image of Rachel
NOAA's GOES-West satellite captured an image of the smaller, fading Tropical Storm Rachel and the large developing System 90E in the Eastern Pacific on Sept. 30 at 8 a.m. EDT.
Image Credit: 
NASA/NOAA GOES Project
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Page Last Updated: September 30th, 2014
Page Editor: Lynn Jenner