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Hurricane Season 2009: Tropical Storm Felicia (Eastern Pacific)
08.13.09
 
August 13, 2009

GOES-11 captured all four tropical areas in the Pacific on August 13 at 8 a.m. EDT. > View larger image
GOES-11 captured all four tropical areas in the Pacific on Aug. 13 at 8 a.m. EDT: from left to right, the remnants of Maka and Felicia, then TD9E and finally,Tropical Storm Guillermo, which looks pretty impressive west of the Mexican coast.
Credit: NASA/GOES Project
GOES-11 captured all four tropical areas in the Pacific on August 13 at 8 a.m. EDT. > View larger image
This is a "full-disk" image of the Earth taken by GOES-11. In the image, north of the equator, you can see where GOES-11 captured all four tropical areas in the Pacific on Aug. 13 at 8 a.m. EDT: from left to right, the remnants of Maka and Felicia, then TD9E and finally,Tropical Storm Guillermo.
Credit: NASA/GOES Project
GOES-11 Sees Tropical Cyclones Fizzling and Forming in the Eastern Pacific!

There are a lot of ups and downs in tropical cyclone formation in the Pacific Ocean this week, and that's keeping NOAA's GOES-11 satellite busy. There are remnants of Maka and Tropical Depression 9E, a fizzled Felicia, and a new Tropical Storm named Guillermo.

The graphics folks that create images from the satellite at the GOES Project at NASA Goddard Space Flight Center in Greenbelt, Md. are posting updated images on the GOES Project website often and forecasters are watching them.

In the Central Pacific Ocean, Maka and Felicia are now a memory. Felicia dissipated before it reached Hawaii, and the remnants of Maka are 1,400 miles west-southwest of Kauai. Maka's remnant clouds and showers are still moving west, and it's unlikely that it will re-organize. That means a quiet Central Pacific Ocean for the next two days.

In the Eastern Pacific, Tropical Depression 9E (TD9E) appears to be fizzling although it may get a second chance at life, while Tropical Depression 10E powered up into Tropical Storm Guillermo.

The remnants of TD9E are weakly spinning to around 30 mph, while it continues moving west-southwest near 9 mph. The center was located about 1,750 miles west-southwest of the southern tip of Baja California, near 13.9 north and 134.1 west. The National Hurricane Center noted that shower and thunderstorm activity has increased this morning, and the environment seems to be a little more conducive to strengthening, so TD9E isn't written off yet. In fact, there's about a 30-50% chance it may strengthen back into a tropical depression.

Meanwhile, Tropical Depression 10E gained strength took the name Guillermo and it's sustained winds whipped up to near 50 mph. Guillermo is moving west-northwest near 16 mph and will continue in that direction. Guillermo is closer to mainland Mexico, but poses no threat as its heading away from land. On Aug. 13 at 5 a.m. EDT the storm was located 805 miles west-southwest of the southern tip of Baja California near 16.9 north and 120.5 west. His minimum central pressure is 999 millibars. Guillermo is moving into a favorable environment, so he's expected to continue strengthening.

Even though the peak of hurricane season in the eastern and central Pacific Oceans are a month away, it seems like we're already there.

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



August 12, 2009

From left to right: Trop. Depression Maka, Felicia, Tropical Depression 9E, and a developing low near Mexico. > View larger image
GOES-11 captured four tropical areas on Aug. 12 at 8 a.m. EDT, from left to right: Trop. Depression Maka, Felicia, now a low pressure area, Tropical Depression 9E, and a developing low near Mexico.
Credit: NASA/GOES Project
> View larger image
This is a "full-disk" image of the Earth taken from the GOES-11 satellite at 8 a.m. EDT on Aug. 12.
Credit: NASA/GOES Project
GOES-11 Satellite Captures a Very Busy Central and Eastern Pacific Ocean

The GOES-11 satellite is getting a lot of business today, August 12. There are four areas of tropical interest between the Central and the Eastern Pacific Ocean today: two near Hawaii and two from a couple hundred to a thousand miles off the Mexican coast, and GOES-11 captured them all in one image.

GOES-11, or the Geostationary Operational Environmental Satellite is operated by the National Oceanic and Atmospheric Administration. NASA's GOES Project at the Goddard Space Flight Center in Greenbelt, Md. creates some of the GOES images, and they made a stunning image that captures four current areas of interest in the Pacific.

Farthest west lies a new tropical depression in the Central Pacific called Maka. Maka has sustained winds near 35 mph, but is expected to strengthen into a tropical storm as it starts to turn toward the northwest near 12 mph. Maka formed late on Tues. August 11 and 5 a.m. EDT on Aug.ust 12, it was located far to the west-southwest of Honolulu, Hawaii, about 1,125 miles from there. That puts its center near 14.6 north and 173.5 west, also 305 miles west-southwest of Johnston Island.

Moving eastward, and located to Maka's northeast is what is left of the once powerful Felicia. She's now a remnant low pressure system, and is located just east of Maui and the Alenuihaha Channel within the main Hawaiian island chain. The low will move west very slowly over the next couple of days, and isn't expected to redevelop.

The third tropical area is Tropical Depression 9E (TD9E), lingering in the Eastern Pacific Ocean. TD9E is poorly organized and isn't expected to strengthen over the next day, but may become a tropical storm at sea over the weekend. At 11 a.m. EDT on August 12, TD9E's center was located about 1,590 miles west-southwest of the southern tip of Baja California, near 14.6 north and 132.6 west. Its maximum sustained winds were near 30 mph, and it was moving 14 mph toward the west. Minimum central pressure is 1007 millibars.

Farthest east in the Pacific, and closest to mainland Mexico is a broad low pressure area that looks pretty significant on satellite imagery. It's about 600 miles south-southwest of the southern tip of Baja California and moving west-northwest near about 12 mph. The storm is expected to strengthen into a tropical depression and get a name soon.

The GOES-11 satellite captured all four areas of tropical activity in one stunning image at 8 a.m. EDT on August 12. It's a busy season in the eastern Pacific and GOES is watching.

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



August 11, 2009

Flooding Possible with a Weakened Tropical Depression Felicia

Felicia was barely a tropical storm when the TRMM satellite passed overhead on August 10. > View larger image
Felicia was barely a tropical storm when the Tropical Rainfall Measuring Mission (TRMM) satellite passed overhead on August 10, 2009 at 2051 UTC (10:51 a.m. HST).
Credit: NASA/SSAI, Hal Pierce
Felicia as she was approaching Hawaii on August 11 at 8:11 a.m. EDT (12:11 UTC ). > View larger image
AIRS captured an infrared image of the waning Felicia as she was approaching Hawaii on Aug. 11 at 8:11 a.m. EDT (12:11 UTC ). The blue coloration in the clouds suggests thunderstorms are not as powerful as they were and her strength is fading.
Credit: NASA JPL, Ed Olsen
NASA's Tropical Rainfall Measuring Mission satellite (TRMM) has been eyeing Felicia's rainfall, and forecasters believe there can still be some heavy downpours from her as she sweeps over the Hawaiian Islands. Felicia has now weakened into a tropical depression, but depressions can cause some serious flooding, so residents in Hawaii need to be on guard. There are also several watches and warnings up for the islands.

A Tropical Storm Watch is in effect for Oahu, Molokai, Lanai, Kahoolawe, Maui and the Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Maalaea Bay, Pailolo Channel. There is still a slight chance that the system could produce tropical storm force winds unexpectedly...so a tropical storm watch remains in effect. In anticipation of heavy rainfall, Flash Flood Watches stand for Niihau, Kauai, Oahu, Molokai, Lanai, Maui and Kahoolawe through Wednesday afternoon. In addition, there's a high surf warning for the eastern facing shores of Niihau, Kauai, Oahu, Molokai and Maui until 6pm HST today, August 11.

At 5 a.m. HST (11 a.m. EDT) Tropical Depression Felicia was only 155 miles east of Kahului, Hawaii, near 20.9 north and 154.1 west. Felicia's sustained winds are now down to 35 mph, and she was moving west near 10 mph.

For local hurricane statements on Felicia, go to: http://www.prh.noaa.gov/hnl/pages/watchwarn.php#Hurricane_Local_Statements_(%3Ca%20href=http://www.prh.noaa.gov/cphc%3ECPHC%20Bulletins%3C/a%3E).

Felicia was barely a tropical storm when the Tropical Rainfall Measuring Mission (TRMM) satellite passed overhead on August 10, 2009 at 2051 UTC (10:51 a.m. HST). The TRMM rainfall analysis derived from the TRMM Microwave Imager (TMI) and Precipitation Radar (PR) instruments was overlaid on a combined Visible and Infrared image from the Visible and Infrared Scanner (VIRS). This rainfall analysis showed that very little heavy rainfall was associated with Felicia and a low level circulation is almost all that remained of the once powerful hurricane.

NASA's Aqua satellite also flew over Felicia and captured an infrared image with the Atmospheric Infrared Sounder (AIRS) instrument of the waning Felicia as she was approaching Hawaii on August 11 at 8:11 a.m. EDT (12:11 UTC ). The image, which reveals cloud temperatures, showed that Felicia's clouds were not as cold as they were over the last few days, revealing a weakening storm. Colder cloud temperatures mean higher clouds, and more powerful thunderstorms. The AIRS image shows that Felicia is losing her punch.

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



Tropical Storm Watches Up for Hawaii Today

Tropical Storm Felicia's clouds in the early morning hours of August 11, 2009. > View larger image
The GOES-11 satellite captured an infrared image of Tropical Storm Felicia's clouds (located top center) in the early morning hours of August 11, 2009 in the Eastern Pacific Ocean. Notice that Felicia no longer has a circular shape indicating weakening.
Credit: NASA/NOAA GOES Project
Residents on the Hawaiian Islands are bracing for Tropical Storm Felicia's heavy rains and gusty winds today and the next couple of days as travels through the island chain. Large and dangerous ocean swells have already reached the main island, and will sweep into the rest of the state through today, August 11.

The Central Pacific Hurricane Center noted that a tropical storm watch remains in effect today for Oahu and for all of Maui County...which includes the islands of Maui...Kahoolawe...Lanai...and Molokai.

At 2 a.m. HST Felicia was still a tropical storm with sustained winds near 40 mph, and was closing into the Hawaiian Island chain. Her center was located 190 miles east of Jahului, Hawaii and 280 miles east of Honolulu. That’s near latitude 20.8 north and longitude 153.5 west . Because tropical storm force winds extend 100 miles from her center, they'll be felt, along with rains, long before her center approaches the islands.

She's continuing to move westward near 10 mph and will start moving west-northwest over the next couple of days. Minimum central pressure is 1007 millibars. She's expected to weaken late tonight into a depression.

GOES-11, the Geostationary Operational Environmental Satellite provided infrared imagery of Felicia's clouds at 8 a.m. EDT on August 11. It revealed that Felicia no longer has the circular shape- indicating a weakening storm. Felicia is expected to weaken to a depression late tonight, August 11.

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



August 10, 2009

NASA Satellites Catch Two Views of Felicia Already Affecting Hawaii

Felicia is due east of Hilo Aug. 9, at 23:11 UTC. > View larger image
Felicia is weakening, and is seen in (in blue) the North half of this image from the AIRS instrument. Felicia is due east of Hilo Aug. 9, at 23:11 UTC (7:11 p.m. EDT) and there is another depression forming to the southwest (blue area) in the lower half of this image.
Credit: NASA/JPL, Ed Olsen
The CloudSat image indicates Felicia's highest clouds are now down to around 13 kilometers high. > View larger image
The CloudSat image indicates Felicia's highest clouds are now down to around 13 kilometers (8 miles) high (they were higher than 15 km).
Credit: NASA/JPL/Colo.St.Univ./NRL-Monterey
Tropical Storm Felicia is closing in on the Hawaiian Island chain and its center is now expected to pass just north of the big island before moving through the islands Tuesday and Wednesday. Two NASA satellites captured the height and temperatures of Felicia's clouds to assist meteorologists in their forecasts as she approaches Hawaii. She's already stirring up the surf.

A Tropical Storm Watch Remains in effect for Oahu, the Big Island of Hawaii and for all of Maui County, which includes the islands of Maui, Kahoolawe, Lana, and Molokai. A tropical storm watch means that tropical storm conditions are possible within the watch area. If Felicia does not weaken to a tropical depression later today...a tropical storm warning may be required for portions of the watch area.

The Central Pacific Hurricane Center in Honolulu, Hawaii noted in their discussion "a large swell generated by Felicia is already affecting the main Hawaiian islands. This swell will continue to build across the state today and tonight. Also...regardless of the intensity of Felicia when it reaches the Hawaiian Islands...locally heavy rainfall is still expected to occur and flash flooding remains a possibility."

What's it like to see a tropical storm from space and from the side? NASA has the answers, thanks to two satellites: CloudSat, that takes a "profile" view of a storm, and Aqua, that sees it from the top down. Those are just two of NASA's earth-watching satellites that are helping forecasters calculate what Tropical Storm Felicia's strength will be when it impacts the Hawaiian Island chain late tonight, August 10.

NASA's CloudSat satellite's Cloud Profiling Radar captured a side view of Felicia on August 9 at 7 p.m. EDT (23:00 UTC). The image indicated Felicia's cloudtops are almost 13 kilometers (8 miles) high, down about 2 kilometers over the last several days, which indicates a weakening storm. Higher clouds indicate stronger uplift in a storm, and a more powerful hurricane.

Meanwhile, another satellite and instrument are taking Felicia's cloud temperatures from space. The Atmospheric Infrared Sounder (AIRS) is an instrument that flies aboard NASA's Aqua satellite and takes infrared images that reveal temperatures of clouds. NASA false-colors the images to show temperature differences, and the lowest temperatures (in purple) are associated with high, cold cloud tops that make up the top of the area of low pressure. Those temperatures are as cold as or colder than 220 degrees Kelvin or minus 63 degrees Fahrenheit (F). The blue areas are around 240 degrees Kelvin, or minus 27F. Felicia's cloud top temperatures are mostly blue, indicating lower clouds.

On August 10, at 11 a.m. EDT (5 a.m. Hawaii Time) Felicia had maximum sustained winds near 45 mph, and is expected to continue weakening as it affects Hawaii. It was moving west near 12 mph, and had a minimum central pressure near 1005 millibars. It was located about 3225 miles east of Hilo, Hawaii near 20.5 north and 150.2 west.

Increasing upper level winds continue to batter at Felicia, further weakening the tropical storm. Those winds will continue and Felicia is expected to drop to a tropical depression by late tonight, Aug. 10 or early on Aug. 11 despite traveling through warm ocean waters.

Residents can expect large ocean swells, gusty winds and heavy downpours over the next couple of days.

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



August 7, 2009

Hurricane Felicia Eyeing Hawaii While Weakening on Weekend

Infrared satellite image showing Hurricane Felicia's cold clouds and thunderstorms > View larger image
This infrared satellite image shows Hurricane Felicia's cold clouds (depicted in purple and blue) and thunderstorms in the eastern Pacific Ocean on Aug 7, 2009.
Credit: NASA JPL, Ed Olsen

Still from GOES Project movie of Hurricane Felicia's track through the Eastern Pacific Ocean > Watch movie
NASA's GOES Project created a movie of Hurricane Felicia's track (bottom left corner) through the Eastern Pacific Ocean from Aug. 5 through Aug. 7 from NOAA's GOES-11 satellite. It clearly showed Felicia's eye when she was a Category 4 hurricane. Tropical Storm Enrique was northeast of Felicia.
Credit: NASA/NOAA GOES Project
NASA satellite imagery has helped forecasters see that Hurricane Felicia is running into cooler waters and increasing wind shear, two things have taken her strength "down a peg or two." Felicia will continue to weaken further over the weekend as she heads to Hawaii where landfall isn't expected until late Monday or early Tuesday.

By Friday, Aug. 7 at 11 a.m. EDT (5 p.m. Hawaiian Time), Felicia had weakened from a Category four hurricane on the Saffir-Simpson scale to a Category two hurricane with sustained winds near 100 mph. Additional weakening is expected over the weekend, and forecasters at the National Hurricane Center are forecasting that by Monday, Aug. 10 Felicia will be a tropical storm.

Felicia is moving west-northwest near 13 mph and will turn toward the west over the weekend. Her minimum central pressure continues rising and is currently 973 millibars. Rising air pressure means a weakening storm, and that's good news for the big island of Hawaii.

Over the weekend as Felicia continues her track toward Hawaii, she's running into cooler waters that will continue sapping her strength. Hurricanes need warm waters of at least 80 degrees Fahrenheit to maintain strength. In addition, vertical wind shear (winds that can weaken and tear a storm apart) will increase from the west.

AIRS captured an infrared image of Hurricane Felicia tracking through the Eastern Pacific Ocean on August 7 at 6:59 a.m. EDT showing a tight circular shape, indicating she's still a powerful hurricane.

AIRS provides visible, infrared and microwave images of tropical storms. Infrared imagery shows the temperature of the cloud tops which gives a hint about the power of the thunderstorms in a tropical cyclone. The colder the clouds are, the higher they are, and the more powerful the thunderstorms are that make up the cyclone.

NASA also creates imagery from a satellite operated by the National Oceanic and Atmospheric Administration and created a movie of Hurricane Felicia's track through the Eastern Pacific Ocean. Images from Aug. 5 through Aug. 7 from the Geostationary Operational Environmental Satellite (GOES-11) were put together as a movie. NASA's GOES Project, located at NASA's Goddard Space Flight Center, Greenbelt, Md. created the movie that clearly shows Felicia as a powerful Category Four hurricane with a very visible eye.

Interests in the Hawaii should monitor Felicia's progress closely over the weekend.

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

Ferocious Felicia Becomes a Major Hurricane

TRMM reveals estimated wind speeds over 81 miles per hour and rainfall of over 2 inches per hour. > View larger image
TRMM passed over Felicia late on Aug. 4 when wind speeds were estimated to be over 81 miles per hour. Very heavy rainfall of over 2 inches per hour was shown by the TRMM analysis in the southeastern edge of the forming eye.
Credit: NASA/SSAI, Hal Pierce
By noon EDT on August 5, Hurricane Felicia had strengthened to a major hurricane with sustained winds near 115 mph on its westward track in the Eastern Pacific Ocean.

At that time, it was about 1,370 miles west-southwest of the southern tip of Baja California, near 14.1 north latitude and 128.7 west longitude. It was moving northwest near 12 mph and had a minimum central pressure near 955 millibars. Hurricane force winds were compact, and extended 35 miles out from its center, while tropical storm force winds went much farther out, as far as 120 miles from the center!

The Tropical Rainfall Measuring Mission (TRMM) satellite flew above Felicia at 7:17 p.m. EDT (2317 UTC) on Aug. 4 and captured data on Felicia's rainfall. A TRMM based rainfall analysis derived from the TRMM Microwave Imager (TMI) and Precipitation Radar (PR) instruments was overlaid on a Visible and Infrared image from the Visible and Infrared Scanner (VIRS) to provide forecasters with a look at how intense the rain was falling inside Felicia.

At the time of the analysis wind speeds were estimated to be over 70 knots (~81 miles per hour). Very heavy rainfall of over 50 millimeters per hour (~ 2 inches per hour) was shown by the TRMM analysis in the southeastern edge of the forming eye.

The National Hurricane Center expects Felicia to maintain intensity of the next couple of days.

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



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

Felicia: The Sixth Tropical Storm of the Eastern Pacific

Felicia on Aug. 4 at 6:29 a.m. EDT, just as it strengthened into a tropical storm. > View larger image
NASA's AIRS instrument captured an infrared image of Felicia on Aug. 4 at 6:29 a.m. EDT, just as it strengthened into a tropical storm. The tight rounded shape indicates an organized storm.
Credit: NASA JPL, Ed Olsen
It didn't take long for the eighth tropical depression of the Eastern Pacific season to strengthen into a tropical storm. Tropical Storm Felicia's sustained winds are now up to 45 mph and getting stronger.

At 11 a.m. EDT, on August 4, Felicia was moving west-northwest near 14 mph, still more than 400 miles ahead of Tropical Storm Enrique in the open waters of the Eastern Pacific Ocean. Felicia was located near 124.9 west and 12.7 north, about 1,210 miles west southwest of the southern tip of Baja California. Minimum central pressure is 1001 millibars.

The center of a tropical cyclone isn't always in the middle of it. In Felicia's case, the National Hurricane Center states "The center appears to be in the northeastern portion of a prominent banding feature with very cold cloud tops."

The Atmospheric Infrared Sounder (AIRS) that flies aboard NASA's Aqua satellite is used in tropical storm research by measuring cloud top temperature and pressure. AIRS captured an infrared image of Felicia on Aug. 4 at 6:29 a.m. EDT, just as it strengthened into a tropical storm. The image it captured shows a tight rounded shape, indicating an organized storm.

Infrared imagery is useful to forecasters because it shows the temperature of the cloud tops, facilitating the recognition of deep convective cells. NASA false-colors clouds at different heights in the infrared satellite images, so that the highest clouds appear purple, and the second highest clouds appear in blue. How does infrared imagery know how high clouds are in the sky? The coldest ones are higher in the sky (because in the troposphere, the lowest layer of atmosphere where weather happens, temperatures fall the higher up you go until you get to the stratosphere).

In infrared imagery, NASA's false-colored purple clouds are as cold as or colder than 220 Kelvin or minus 63 degrees Fahrenheit (F). The blue colored clouds are about 240 Kelvin, or minus 27F. The colder the clouds are, the higher they are, and the more powerful the thunderstorms are that make up the cyclone.

The National Hurricane Center notes that "further intensification is expected over the next couple of days as Tropical Storm Felicia remains over warm water with light (wind) shear. Beyond that time, a combination of increasing easterly shear from Tropical Storm Enrique and cooler waters could limit any future strengthening."



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