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Hurricane Season 2011: Katia (Atlantic Ocean)
09.14.11
 
This image of Hurricane Katia was taken from the MODIS instrument on NASA's Terra satellite on Sept. 9 at 11 a.m. EDT › View larger image
This image of Hurricane Katia was taken from the MODIS instrument on NASA's Terra satellite on Sept. 9 at 11 a.m. EDT when it was off the New England coast.
Credit: NASA Goddard MODIS Rapid Response Team
Hurricane Katia Caused Damage in the U.K.

Hurricane Katia caused rough surf along the U.S. east coast but never made landfall until it crossed the Atlantic Ocean. Katia held together on its ocean journey and brought hurricane-force winds to the U.K. this week.

The U.K. Daily Mail reported that the damages from Hurricane Katia are expected to be as high as "tens of millions of pounds." Katia battered the U.K. with hurricane-force wind gusts, downing trees and damaging structures. The highest wind gust was 82 mph at Capel Curig in north Wales.

The northern U.K. was most affected by Katia and the Mail called the storm damage "the worst in 15 years in Britain."

Katia caused thousands of residents to lose power, downing trees onto powerlines. Rough surf caused cancellations of ferry service, and Katia's heavy rains caused inland flooding.

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



September 9, 2011

GOES image of Katia from Sept. 9, 2011 › View larger image
NOAA's GOES-13 satellite captured a visible image of Hurricane Katia onFriday, Sept. 9 at 9:32 a.m. EDT sitting 525 miles south-southwest of Halifax, Nova Scotia, Canada.
Credit: NASA/NOAA GOES Project
Hurricane Katia Headed to the U.K. This Weekend

Satellite imagery shows Hurricane Katia's western edge near New England today, but she's forecast to head to old England this weekend.

NOAA's Geostationary Operational Environmental Satellite, GOES-13, captured a visible image of Hurricane Katia today, Friday, Sept. 9 at 9:32 a.m. EDT sitting 525 miles south-southwest of Halifax, Nova Scotia, Canada. Katia is centered near 37.6 North and 67.5 West. It is speeding along at 21 knots and it is a Category one hurricane on the Saffir-Simpson scale with maximum sustained winds near 75 knots. Katia appears quite large on the GOES-13 image and that's because her tropical-storm force winds extend 255 miles from the center, making her over 510 miles in diameter!

The GOES image, created by NASA's GOES Project at NASA's Goddard Space Flight Center in Greenbelt, Md. hints at an eye in Katia's center. There appears to be two small areas near the storm's center where the Atlantic Ocean can be seen on the image.

The National Hurricane Center is forecasting some weakening over the next 48 hours and a transition into a post-tropical cyclone (and become like a typical low pressure system). Because Katia is already embedded into the northern hemisphere's mid-latitude westerly winds, they'll help bring her across the north Atlantic over the weekend. Katia is expected to bring the United Kingdom winds and rains by Sunday.

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



September 8, 2011

NASA Sees 4 Tropical Cyclones in the Atlantic Today

There are four tropical cyclones or remnants plaguing the Atlantic Ocean basin today, Sept. 8, 2011, and one satellite has captured all four in one image: Katia, Lee, Maria and Nate.

GOES image of four Atlantic Storms on Sept. 8, 2011 NOAA's GOES-13 satellite took a stunning image of 4 tropical systems in the Atlantic today, Sept. 8, 2011. Hurricane Katia in the western Atlantic between Bermuda and the U.S. East coast; Tropical Storm Lee's remnants affecting the northeastern U.S.; Tropical Storm Maria in the central Atlantic; and newborn Tropical Storm Nate in the Bay of Campeche, Gulf of Mexico. (Credit: NASA/NOAA GOES Project)
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NOAA's GOES-13 satellite monitors the Atlantic and eastern U.S. and took a stunning image of Hurricane Katia in the western Atlantic between Bermuda and the U.S. East coast; Tropical Storm Lee's remnants affecting the northeastern U.S.; Tropical Storm Maria in the central Atlantic; and newborn Tropical Storm Nate in the Bay of Campeche, Gulf of Mexico. The visible image was created by the NASA GOES Project at NASA's Goddard Space Flight Center, Greenbelt, Md.

Hurricane Katia

AIRS image of Katia NASA's AIRS instrument on the Aqua satellite took this infrared image of Hurricane Katia on Sept. 8 at 2:29 a.m. EDT. The infrared data shows the coldest cloud top temperatures (purple) and strongest thunderstorms with the heaviest rainfall were from the north to the east and south of the center. Credit: NASA JPL, Ed Olsen
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Hurricane Katia is causing rough surf along the U.S. east coast, and fortunately that's all she'll do. Today, Sept. 8, 2011, her center is passing between Bermuda and the east coast of the U.S. Bermuda is still under a tropical storm watch. Katia's eye is still visible in today's GOES-13 image.

NASA's Aqua satellite's AIRS instrument measured the cloud top temperatures within Hurricane Katia on Sept. 8 at 2:29 a.m. EDT. The infrared data showed the coldest cloud top temperatures (-63F/-52C) and strongest thunderstorms with the heaviest rainfall extended from the north to the east and south of the center. The AIRS imagery was created at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

At 11 a.m. EDT, Katia's maximum sustained winds were near 90 mph (150 kmh) and holding steady from earlier today. Katia was located about 320 miles (515 km) west of Bermuda near 33.6 North and 70.1 West. She was moving to the north at 16 mph (26 kmh) and had a minimum central pressure of 970 millibars.

Those rough surf conditions are expected along the U.S. East coast, Bermuda, and east facing beaches in the Bahamas over the next couple of days. Dangerous rip currents and very rough surf are expected in these areas.

Lee's Remnants

On the GOES-13 satellite image, the large area of cloud cover over the eastern U.S. is indicative of Lee's remnants. Gulf and Atlantic moisture associated with the remnants of Tropical Depression Lee were absorbed into a large scale extra-tropical low pressure area currently over east-central Ohio. That low continues to generate widespread rain from the Mid-Atlantic to southwestern New England today. Flood and flash flood watches and warnings are in effect over the northern part of the mid-Atlantic states, eastern Pennsylvania and southwestern New England.

The National Oceanic and Atmospheric Administration's (NOAA) Hydrometeorological Prediction Center forecast today concerning Lee's remnants calls for "very heavy rain with embedded thunderstorms has been persisting along two rainbands across the mid-Atlantic into southwestern part of New England. Additional rainfall amounts of 2 to 4 inches are expected today...with isolated amounts of up to 6 inches possible." The extra-tropical low is expected to dissipate slowly over the weekend.

Tropical Storm Maria

Tropical Storm Maria appears smaller than Lee, Katia and Nate on today's GOES-13 visible satellite image. Its cloud cover also appears to be less organized than Katia (understandable since she's a hurricane) and tropical storm Nate (that just formed late last night, Sept. 7). At 11 a.m. EDT today, Sept. 8, even the National Hurricane Center called Maria "not well organized."

At that time, Maria's maximum sustained winds decreased to 45 mph from just three hours beforehand. She was centered about 660 miles (1060 km) east of the Windward Islands near 13.0 North and 51.2 West. She was moving to the west near 22 mph (35 kmh), and is the fastest moving of all the Atlantic tropical cyclones today. Her minimum central pressure rose by three millibars in the last three hours to 1005 millibars, indicating weakening.

NASA's Aqua satellite's AIRS instrument caught an infrared image of Tropical Storm Maria on Sept. 8 at 1:53 a.m. EDT. The infrared data shows the coldest cloud top temperatures (-63F/-52C) and strongest thunderstorms with the heaviest rainfall were seen in patches north of the center and were not throughout the entire circulation.

Maria has prompted a tropical storm watch is in effect for the Leeward Islands of Antigua, Barbuda, Montserrat, Nevis and Saint Kitts. A tropical storm watch is also in effect for St. Barthelemy, St. Marteen, Guadeloupe, and Martinique, Dominica, St. Maartin, Saba and St. Eustatius.

The National Hurricane Center did note that "surface observations and satellite imagery suggest that Maria could be degenerating into a tropical wave," so forecasters are keeping a close eye on the storm.

Tropical Storm Nate

Nate appears as a small rounded area of clouds on today's GOES-13 satellite image. The rounded area of clouds coincides with the strongest thunderstorms and heaviest rainfall on Nate's southern side.

At 11 a.m. EDT on Sept. 8, Nate's maximum sustained winds were near 50 mph, and are expected to strengthen in the warm waters of the Bay. Nate was located about 125 miles (200 km) west of Campeche Mexico near 20.2 North and 92.4 West. Nate is creeping to the southeast near 1 mph (2 kmh) and has a minimum central pressure of 1001 millibars. The forecast from the National Hurricane Center calls for Nate to become a hurricane over the weekend and make landfall in eastern Mexico early next week.

A tropical storm warning is in effect from Chilitepec to Celestun, Mexico and a tropical storm watch is in effect from Celestun to Progreso.

The first and second week of September are typically known as being the peak of hurricane season, and Lee, Katia, Maria and Nate are living up to that call and giving satellites a lot to see.

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



September 07, 2011

GOES image of Tropical Storm Maria and Hurricane Katia › View larger image
GOES-13 captured the clouds associated with tropical Storm Lee's remnants, and a warm front along the U.S. East coast on Sept. 7 at 9:02 a.m. EDT. Hurricane Katia is moving between Bermuda and the U.S., while farther east is newborn Tropical Storm Maria. Credit: NASA/NOAA GOES Project
NASA Panorama Sees Tropical Storm Maria Join Hurricane Katia

Newborn Tropical Storm Maria joined Hurricane Katia in the Atlantic Ocean today. Both storms were seen on an impressive panoramic satellite view from the GOES-13 satellite, one in the central Atlantic, and the other in the western Atlantic near the U.S.

An image from NOAA's GOES-13 satellite today showed newborn Tropical Storm Maria about 1305 miles (2,095 km) east of the Lesser Antilles this morning, Sept. 7, at 11 a.m. EDT. The National Hurricane Center (NHC) reported Maria's center near 13.0 North and 42.0 West. Maria's maximum sustained winds were near 50 mph and is expected to strengthen over the next two days. Maria is moving to the west near 23 mph (37 kmh) and this general motion is expected to continue during the next two days. Estimated minimum central pressure is 1003 millibars. Currently, Maria is no threat to land but could pose a threat to the Lesser Antilles this weekend.

GOES-13 captured a panorama of the Atlantic Ocean today, as it does every day. Today, however, it revealed clouds associated with tropical Storm Lee's remnants over the U.S. east coast, Hurricane Katia is moving between Bermuda and the U.S., while farther east is newborn Tropical Storm Maria. The GOES image was created at NASA's GOES Project, located at NASA's Goddard Space Flight Center, Greenbelt, Md.

Hurricane Katia appears much more impressive on the GOES-13 satellite imagery because she's a Category one hurricane on the Saffir-Simpson scale with maximum sustained winds near 85 mph. Although a hurricane, today's GOES-13 image did not reveal an eye in visible imagery.

Katia has prompted a tropical storm watch for Bermuda. At 11 a.m. EDT on Sept. 7, Katia's center was about 320 miles (515 km) southwest of Bermuda near 29.2 North and 68.8 West. It was moving toward the northwest near 10 mph (17 kmh) and is expected to turn toward the north-northwest then north-northeast tomorrow, moving between the eastern U.S. and Bermuda. Katia is about 410 miles in diameter, so tropical storm force-winds were already reaching Bermuda this morning.

The NHC continues to warn of large swells created by Katia to affect most of the U.S. east coast, Bermuda and greater Antilles. Katia is forecast to generate 1 to 2 inches of rain over Bermuda.

While all eyes are on Katia today as she affects Bermuda, forecasters will later be turning their attention to Maria who will be closing in on the Caribbean.

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



MODIS captured this visible image of Hurricane Katia on Sept. 5 at 11:30 a.m. EDT. › View larger image
The MODIS instrument on NASA's Terra satellite captured this visible image of Hurricane Katia on Sept. 5 at 11:30 a.m. EDT. Katia is a major hurricane in the Atlantic Ocean, and her eye, although filled with some clouds, remains visible.
Credit: NASA Goddard/MODIS Rapid Response Team
MODIS satellite captured this visible image of Hurricane Katia on Sept. 4 at 10:45 a.m. EDT › View larger image
The MODIS instrument on NASA's Terra satellite captured this visible image of Hurricane Katia on Sept. 4 at 10:45 a.m. EDT and her eye was entirely cloud-filled, despite being a hurricane.
Credit: NASA Goddard/MODIS Rapid Response Team
This mage of Katia was taken by MODIS at 12:25 p.m. AST on September 2. › View larger image
At 11:00 a.m. AST, September 2, Hurricane Katia had winds of 75 miles (120 kilometers) per hour with higher gusts. This natural color image was taken by the MODIS instrument on NASA’s Aqua satellite at 12:25 p.m. AST on September 2. Katia swirls over the water east of the Leeward Islands. Although the hurricane lacks a distinct eye, it sports the spiral shape characteristic of strong storms.
Credit: NASA Goddard/MODIS Rapid Response Team
NASA Satellites "Eyes" Changes in Hurricane Katia

Major Hurricane Katia continues to approach the U.S. East coast and stir up rough surf. Meanwhile two NASA satellites have provided a look at the changes in organization and cloud patterns over the last several days.

One NASA instrument that flies aboard two different NASA satellites has been providing very clear pictures of Hurricane Katia's transition over the last couple of days. The Moderate Resolution Imaging Spectroradiometer or MODIS instrument flies on NASA's Aqua and Terra satellites.

At 11:00 a.m. AST, September 2, Hurricane Katia had winds of 75 miles per hour with higher gusts when MODIS captured a natural color image of her. The image was taken by the MODIS instrument on NASA’s Aqua satellite at 12:25 p.m. AST when Katia was east of the Leeward Islands. Although the hurricane lacked a distinct eye, it sported the spiral shape characteristic of strong storms.

Two days later, the MODIS instrument on NASA's Terra satellite captured a visible image of Hurricane Katia and her eye was completely cloud-filled. Then, on Sept. 5 at 11:30 a.m. EDT, when Katia was a major hurricane in the Atlantic Ocean, some of the cloud cover cleared over her eye as a testament to her major hurricane status.

On Sept. 6, Hurricane Katia appeared less symmetric and once again, her eye was less obvious. Satellite imagery indicated a double-eyewall within the storm, suggestions that Katia is undergoing eyewall replacement again (which happens in major hurricanes).

The National Hurricane Center noted that "the large-scale atmospheric and oceanic environment are likely to remain conducive for Katia to maintain major hurricane status."

At 5 a.m. EDT on Sept. 6, Hurricane Katia's maximum sustained winds were near 125 mph with higher gusts. That makes Katia a Category 3 hurricane on the Saffir-Simpson scale and a major one. Katia was about 400 miles (645 km) south of Bermuda near latitude 26.5 north and longitude 65.1 west. Katia is moving toward the northwest near 10 mph (17 km/h) and will continue in that direction one more day before turning to the north-northwest by Thursday.

A slow-moving cold front and the remnants of Tropical Storm Lee are blocking powerful Hurricane Katia from coming closer to the U.S. However, Katia is close enough to create rough and hazardous surf and rip currents along the U.S. east coast. Bermuda, the greater Antilles and east-facing beaches of the Bahamas are also expected to experience large and dangerous swells, rip currents and life-threatening surf over the next several days.

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

















September 02, 2011

NASA Watching Atlantic Tropics: Katia, Tropical Depression 13 and System 94L

GOES image showing Katia, TD13 and System 94L.
This GOES-13 satellite image shows Hurricane Katia (right), Tropical Depression 13 (left) and System 94L (top). Credit: NASA/NOAA GOES Project

There are three areas of tropical trouble brewing in the Atlantic Ocean Basin today and they'll be there over the Labor Day holiday weekend. NOAA's GOES-13 satellite today provided a look at the location and development of Hurricane Katia in the central Atlantic, newborn Tropical Depression 13, and developing System 94L in the north Atlantic off the New England coast.

The GOES-13 image was created by NASA's GOES Project at NASA's Goddard Space Flight Center in Greenbelt, Md. The image showed Katia to be the most well-organized of the three systems, although Tropical Depression 13 and System 94L are developing the typical hallmark "comma shape" of a tropical storm.

Tropical Depression 13 is the only one of the three causing watches and warnings, although Katia is roughing up the surf in the Lesser Antilles. Tropical Depression 13 was already causing a lot of problems on Sept. 2 with heavy rainfall along the Louisiana coast, especially because it was almost stationary.

Hurricane Katia, she will remain at sea this weekend and is being buffeted by wind shear keeping her from strengthening, although she did regain hurricane status early on Sept. 2 after weakening to a tropical storm.

On Sept. 2, 2011 at 11 a.m. EDT, Hurricane Katia's winds were 75 mph (120 kmh) - again a Category One hurricane. Katia is about 310 miles in diameter with tropical storm force winds extending 155 miles from the center.

Katia is centered about 705 miles (1135 km) east of the Northern Leeward Islands near 17.5 North and 52.4 West. Katia is moving to the west-northwest near 14 mph (22 kmh) and is expected to slow down over the next couple of days.

Visible imagery from the GOES-13 satellite shows that Katia has become more organized and indicate that an eye may even be forming.

Residents of the Lesser Antilles need to be on guard today and this weekend for rough surf from Hurricane Katia. The National Hurricane Center noted "Swells generated by Katia will begin to affect the Lesser Antilles late on Friday. These could cause life-threatening surf and rip-current conditions."

The National Hurricane Center (NHC) forecast track for Katia looks ominous for late next week, however, as Katia is forecast to become a hurricane and move in a direction toward to U.S. east coast. This weekend, however, she's far enough away from the eastern U.S. to enjoy the days off.

The Atlantic Ocean is doing its best to remind everyone that we're nearing the peak of hurricane season with triple tropical trouble.

For updates over the weekend, visit NASA's Hurricane page on Facebook and Twitter: NASAHurricane.

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



September 01, 2011

TRMM captured a rainfall image of Tropical Storm Katia on August, 31, 2011 2:29 p.m. EDT. › View larger image
TRMM captured a rainfall image of Tropical Storm Katia on August, 31, 2011 2:29 p.m. EDT. Yellow and green indicate rainfall between 20 and 40 millimeters (.78 to 1.57 inches) per hour. Dark red areas are considered heavy rainfall, as much as 50 mm (2 inches) of rain per hour. Credit: SSAI/NASA, Hal Pierce

This infrared image, taken on Sept. 1 at 12:47 a.m. EDT., of Tropical Storm Katia's cold clouds shows large areas of strong convection (purple) surrounding center. ›View larger image
This infrared image of Tropical Storm Katia's cold clouds shows large areas of strong convection (purple) surrounding center. It was taken by the AIRS instrument on NASA's Aqua satellite on Sept. 1 at 12:47 a.m. EDT. Credit: NASA/JPL, Ed Olsen
NASA Sees Katia Become Second Atlantic Hurricane

The second Atlantic Ocean Hurricane was born today, Sept. 1 as Katia strengthened from a tropical storm in the central Atlantic. NASA's TRMM satellite noticed towering thunderstorms within Katia yesterday which clued forecasters that she would become a hurricane today. NASA's Aqua satellite showed strong thunderstorms around Katia's center today as the hurricane continues to strengthen.

The Tropical Rainfall Measuring Mission (TRMM) satellite can measure rainfall from its orbit high above the earth and provide heights of towering thunderstorms within a tropical cyclone. Yesterday, August 31, 2011 at 2:29 p.m. EDT (18:29 UTC) TRMM revealed several towering thunderstorms even in Katia's outer bands- that were about 6 miles (10 kilometers) high.

On September 1, the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite showed large areas of strong convection surrounding center. Convection is rapidly rising air that forms the thunderstorms that make up a tropical cyclone. The cloud top temperatures around Katia's center were colder than -63F (-52C) revealing that there's powerful uplift in the atmosphere to create high, cold clouds. AIRS also showed that the sea surface temperatures in the region are over the 80F (26.6C) threshold needed to maintain a tropical cyclone, so that the energy source for Katia remains plentiful and will enable her to strengthen over the weekend.

Katia is a now a Category one hurricane and is expected to bend north-northwest and miss the Leeward Islands. Maximum sustained winds are near 75 mph (120 kmh) with higher gusts, and some strengthening is forecast over the weekend. Katia is still a small storm about 250 miles wide, with hurricane force winds out to 25 miles from the center (35 km) and tropical storm force winds out to 125 miles (205 km).

The National Hurricane Center noted that Katia could become a major hurricane (Category three) over the weekend.

At 11 a.m. EDT on Sept. 1, Katia's center was still far from land. It was about 1050 miles (1,685 km) east of the Leeward Islands, near 15.5 North and 47.5 West. It was moving to the west-northwest near 18 mph (30 kmh) and is expected to slow down.

The National Hurricane Center said Katia is forecast to become a major hurricane on Sunday with winds over 111 mph. It will be between Puerto Rico and Bermuda so NASA will be watching it for the next week.

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



August 31, 2011

This TRMM image is from 4:41 a.m. EDT, Aug. 30, as TD #12 was moving away from the Cape Verde Islands. › View larger image
This TRMM image is from 4:41 a.m. EDT, Aug. 30, as TD #12 was moving away from the Cape Verde Islands. TRMM revealed a sizeable area of moderate rain (shown in green) with embedded areas of heavier rain (shown in red). Within this rain there is evidence of banding (curvature), revealing the presence of a cyclonic circulation. Nearly all of the rain is located south and west of the estimated center.
Credit: SSAI/NASA, Hal Pierce
This image from 4:41 am EDT on Aug. 30, 2011 shows a 3D image of the storm looking west courtesy of the TRMM PR. › View larger image
This image from 4:41 am EDT on Aug. 30, 2011 shows a 3D image of the storm looking west courtesy of the TRMM PR. TRMM showed the presence of some deeper convective towers (shown in red), within the storm. Towers closest to the center of the storm (the nearest) reach about 12.5 km, while those in the outer rain band (farthest way) reach up to 15 km.
Credit: SSAI/NASA, Hal Pierce
Tropical Storm Katia taken by the AIRS instrument on NASA's Aqua satellite on August 31st at 1:05 a.m. › View larger image
This infrared image of Tropical Storm Katia's cold clouds shows banding of thunderstorms around her center. It was taken by the AIRS instrument on NASA's Aqua satellite on August 31st at 1:05 a.m. EDT.
Credit: NASA/JPL, Ed Olsen
TRMM Satellite Sees Heavy Rain, Towering Clouds in Tropical Storm Katia

While parts of the East Coast and New England are still recovering from Hurricane Irene, a new storm is brewing in the Atlantic, Tropical Storm Katia. The TRMM satellite looked "under the hood" of the storm and saw heavy rainfall rates and towering clouds providing a clue that she was going to strengthen and may become a hurricane later today.

Katia began as an area of low pressure that had moved away from the coast of Africa south of the Cape Verde Islands in the central eastern Atlantic. This area of low pressure became the twelfth tropical depression of the season (TD #12) early on the morning of August 29th about 640 km (~400 miles) south-southwest of the Cape Verde Islands and about 1400 km (~870 miles) off the coast of Africa. Storms forming in this region are known as "Cape Verde" storms. They tend to be larger and stronger than average because of the open ocean and occur most often in August and September during the height of the hurricane season. Irene was a Cape Verde storm.

About a day after forming, TD #12 became a little better organized and was upgraded to a tropical storm and given the name Katia. Katia is new on the rotating list of names for tropical storms and hurricanes; it replaces the name Katrina, which was retired after the 2005 hurricane season.

The Tropical Rainfall Measuring Mission satellite (or TRMM) flew over TD #12 and captured images early on the morning of August 30th just before it was upgraded to a tropical storm. The images were taken at 8:41 UTC (4:41 a.m. EDT) August 03, 2011 as TD #12 was moving west northwestward away from the Cape Verde Islands and into the central Atlantic.

The first image TRMM captured showed the horizontal pattern of the rain intensity within the storm. Creating the image was complicated as two products were used to create the image. Rain rates in the center swath are based on the TRMM Precipitation Radar (PR), and those in the outer swath on the TRMM Microwave Imager (TMI). The rain rates were then overlaid on visible and infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS).

TRMM revealed a sizeable area of moderate rain with embedded areas of heavier rain (2 inches/50 mm per hour). Within this rain there was evidence of banding (curvature) that revealed the presence of a cyclonic circulation. However, nearly all of the rain was located south and west of the estimated center. This is due in part to the system not yet being fully developed but also because it was feeling the effects of some northeasterly wind shear.

The second image was taken at the same time and showed a 3-D perspective of the storm. It was created using TRMM's Precipitation Radar. That image revealed some deeper convective hot towers (hot because they release a lot of latent heat), within the storm. Towers closest to the center of the storm (the nearest) reach about 12.5 km 7.7 miles), while those in the outer rain band (farthest way) reach up to 15 km (9.3 miles). These towers are associated with the areas of heavier rain in the previous image and can be a sign of future strengthening when located near the center as they indicate areas within the storm where heat is being released. Shortly after these images were taken, the system became a tropical storm with sustained winds estimated at 35 knots (~40 mph) by the National Hurricane Center (NHC).

At 11 a.m. EDT on August 31, Katia's maximum sustained winds were 65 mph (100 kmh) and expected to strengthen. She was centered near latitude 14.2 north and longitude 40.8 west, about 1100 miles (1765 km) west of the southernmost Cape Verde Islands. Katia is moving toward the west-northwest near 21 mph (33 kmh) and is expected to slow in the next two days. Estimated minimum central pressure is 994 millibars.

Katia is expected to continue on its current west-northwest track passing north of the Leeward Islands. It is also forecast to become a hurricane and possibly a major hurricane as it encounters warmer waters and reduced wind shear.

TRMM is a joint mission between NASA and the Japanese space agency JAXA.

Text credit: Steve Lange, SSAI/NASA's Goddard Space Flight Center, Greenbelt, Md.



August 30, 2011

Tropical Storm Katia seen by GOES on August 30, 2011. › View larger image
GOES-13 passed over Katia (right, center) on August 30, just after daylight reached it in the Atlantic, it revealed a well-developed storm. The bright vertical line on the Earth shows daylight to the east of the line, and imagery is visible. To the left of the line the earth is still in darkness, and infrared imagery shows where the clouds are located.
Credit: NASA/NOAA GOES Project
Dramatic Satellite Image Shows Daylight Breaking Over Newborn Atlantic Tropical Storm Katia

Tropical Depression 12 strengthened into tropical storm Katia as daylight broke in the eastern Atlantic this morning. Stunning satellite imagery from the GOES-13 satellite revealed a well-formed tropical storm as the sun's first rays reached it.

The National Hurricane Center named Katia a tropical storm today, August 30, 2011, at 5 a.m. EDT. As newborn Katia speeds west-northwest the current track projects it moving north of the Leeward Islands on the weekend. Because wind shear is light and sea surface temperatures are warm in the area where Katia is headed, the National Hurricane Center forecasts strengthening into a hurricane.

When NOAA's Geostationary Operational Environmental Satellite, GOES-13 passed over Katia on August 30, just after daylight reached it in the Atlantic, it revealed a well-developed storm. NASA's GOES Project, located at NASA's Goddard Space Flight Center in Greenbelt, Md. created a stunning image from GOES-13 that shows daylight breaking in the eastern Atlantic over Katia, while the U.S. is still dark.

On August 30, at 5 a.m. EDT, Katia's maximum sustained winds were near 40 mph. Additional strengthening is forecast by the National Hurricane Center. Katia is currently a compact tropical storm, only 70 miles in diameter, compared with Irene that was as large as 600 miles in diameter.

Katia was located near latitude 11.8 North and longitude 31.7 West and moving west-northwest near 17 mph (28 kmh). It is expected to continue in this direction for the next two days and speed up. Katia's estimated minimum central pressure is 1006 millibars.

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



August 29, 2011

satellite image of Irene, Jose and TD-12 › View larger image
This GOES-13 image from Monday, August 29 at 7:45 a.m. EDT shows newly formed Tropical Depression 12. The larger version shows an active Atlantic Ocean with the remnants of Hurricane Irene moving into Quebec and Newfoundland and Tropical Storm Jose. Credit: NASA/NOAA GOES Project
NASA Eyes 2 More Atlantic Tropical Cyclones While Irene Drenches Canada

While the remnants of Hurricane Irene drench Quebec and Newfoundland, Canada today, NASA satellites are keeping tabs on two other tropical cyclones in the Atlantic: Tropical Storm Jose and newly formed Tropical Depression 12.

NOAA's GOES-13 satellite, known as the Geostationary Operational Environmental Satellite has been providing infrared and visible images all tropical cyclones over the Atlantic Ocean this season and has now seen the development of the twelfth storm while two others still remain. The NASA GOES Project out of NASA's Goddard Space Flight Center in Greenbelt, Md. created an image from GOES-13 on Monday, August 29 at 7:45 a.m. EDT that shows Irene over eastern Canada, Jose in the central Atlantic and Tropical Depression 12 in the far eastern Atlantic.

On Monday, August 29 at 5 a.m. EDT, the twelfth tropical depression of the Atlantic Ocean season formed in the eastern Atlantic. Tropical Depression 12 (TD12) formed about 395 miles (635 km) south of the Cape Verde Islands, near 9.4 North and 26.3 West. It had maximum sustained winds near 35 mph (55 kmh) and was moving to the west near 15 mph (24 kmh). TD12's minimum central pressure was 1009 millibars. The National Hurricane Center expects strengthening to occur and that would change TD12 into Tropical Storm Katia. Because TD12 is in an environment with low wind shear and warm sea surface temperatures the National Hurricane Center is forecasting the depression to become a tropical storm and even a hurricane later this week.

Farther west, Tropical Storm Jose, that formed on Sunday, August 28, isn't faring so well. Jose is now racing over the North Atlantic, where sea surface temperatures are below the 80F (26.6C) threshold needed to help a tropical cyclone to maintain its strength. So, the National Hurricane Center expects Jose to lose his tropical characteristics later today, August 29.

At 5 a.m. EDT today, Jose's maximum sustained winds were near 40 mph (65 kmh). It is located about 340 miles (545 km) north of Bermuda, and about 515 miles (830 km) of Halifax, Nova Scotia, Canada. It was centered near 37.2 North and 64.7 West. Jose is moving north at 23 mph (37 kmh) and is expected to turn to the north-northeast today. Jose had a minimum central pressure of 1008 millibars.

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